1
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Opoku E, Pawłowski F, Ortiz JV. Ab Initio Electron Propagators with an Hermitian, Intermediately Normalized Superoperator Metric Applied to Vertical Electron Affinities. J Phys Chem A 2024; 128:4730-4749. [PMID: 38814678 DOI: 10.1021/acs.jpca.4c02050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
New-generation ab initio electron propagator methods for calculating electron detachment energies of closed-shell molecules and anions have surpassed their predecessors' accuracy and computational efficiency. Derived from an Hermitian, intermediately normalized superoperator metric, these methods contain no adjustable parameters. To assess their versatility, a standard set (NIST-50-EA) of 50 vertical electron affinities of small closed-shell molecules based on NIST reference data has been created. Errors with respect to reference data on 23 large, conjugated organic photovoltaic (OPV23) molecules have also been analyzed. All final states are valence anions that correspond to electron affinities between 0.2 and 4.2 eV. For a given scaling of the arithmetic bottleneck, the new-generation methods obtain the lowest mean absolute errors (MAEs). The best methods with fifth-power arithmetic scaling realize MAEs below 0.1 eV. Composite models comprising cubically and quintically scaling calculations executed with large and small basis sets, respectively, produce OPV23 MAEs near 0.05 eV. The accuracy of quintically scaling methods executed with large basis sets is thereby procured with reduced computational effort. New-generation results obtained with and without the diagonal self-energy approximation in the canonical Hartree-Fock basis have been compared. These results indicate that Dyson orbitals closely resemble canonical Hartree-Fock orbitals multiplied by the square root of a probability factor above 0.85.
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Affiliation(s)
- Ernest Opoku
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
| | - Filip Pawłowski
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
| | - J V Ortiz
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
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2
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Sedmidubská B, Kočišek J. Interaction of low-energy electrons with radiosensitizers. Phys Chem Chem Phys 2024; 26:9112-9136. [PMID: 38376461 DOI: 10.1039/d3cp06003a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
We provide an experimentalist's perspective on the present state-of-the-art in the studies of low-energy electron interactions with common radiosensitizers, including compounds used in combined chemo-radiation therapy and their model systems. Low-energy electrons are important secondary species formed during the interaction of ionizing radiation with matter. Their role in the radiation chemistry of living organisms has become an important topic for more than 20 years. With the increasing number of works and reviews in the field, we would like to focus here on a very narrow area of compounds that have been shown to have radio-sensitizing properties on the one hand, and high reactivity towards low-energy electrons on the other hand. Gas phase experiments studying electron attachment to isolated molecules and environmental effects on reaction dynamics are reviewed for modified DNA components, nitroimidazoles, and organometallics. In the end, we provide a perspective on the future directions that may be important for transferring the fundamental knowledge about the processes induced by low-energy electrons into practice in the field of rational design of agents for concomitant chemo-radiation therapy.
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Affiliation(s)
- Barbora Sedmidubská
- J. Heyrovský Institute of Physical Chemistry of the CAS, Dolejškova 3, 182223 Prague, Czech Republic.
- Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Břehová 7, 11519 Prague, Czech Republic
- Institut de Chimie Physique, UMR 8000 CNRS and Faculté des sciences d'Orsay, Université Paris Saclay, F-91405 Orsay Cedex, France
| | - Jaroslav Kočišek
- J. Heyrovský Institute of Physical Chemistry of the CAS, Dolejškova 3, 182223 Prague, Czech Republic.
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3
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Van Dorn L, Sanov A. A density-matrix adaptation of the Hückel method to weak covalent networks. Phys Chem Chem Phys 2024; 26:5879-5894. [PMID: 38314532 DOI: 10.1039/d3cp05697j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2024]
Abstract
The coupled-monomers model is built as an adaptation of the Hückel MO theory based on a self-consistent density-matrix formalism. The distinguishing feature of the model is its reliance on variable bond and Coulomb integrals that depend on the elements of the density matrix: the bond orders and partial charges, respectively. Here the model is used to describe electron reactivity in weak covalent networks Xn±, where X is a closed-shell monomer. Viewing the electron as the simplest chemical reagent, the model provides insight into charge sharing and localisation in chains of such identical monomers. Data-driven modelling improves the results by training the model to experimental or ab initio data. Among key outcomes is the prediction that the charge in Xn± clusters tends to localise on a few (2-3) monomers. This is confirmed by the properties of several known cluster families, including Hen+, Arn+, (glyoxal)n-, and (biacetyl)n-. Since this prediction is obtained in a purely coherent covalent regime without any thermal excitation, it implies that charge localisation does not require non-covalent perturbations (such as solvation), decoherence, or free-energy effects. Instead, charge localisation is an intrinsic feature of weak covalent networks arising from their geometry relaxation and is ultimately attributed to the correlation between covalent bond orders and equilibrium bond integrals.
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Affiliation(s)
- Laura Van Dorn
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, USA.
| | - Andrei Sanov
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, USA.
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4
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Tyagi R, Voora VK. Single-Pole Polarization Models: Rapid Evaluation of Electron Affinities of Solvated-Electron and Superatomic Molecular Anionic States. J Phys Chem Lett 2024; 15:1218-1226. [PMID: 38276789 DOI: 10.1021/acs.jpclett.3c03392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2024]
Abstract
We propose a single-parameter effective one-particle potential, termed the single-pole exchange-correlation (1p-XC), to rapidly evaluate electron affinities (EAs) of nonvalence electronic states of molecular clusters and nanoassemblies. The model combines exact-exchange and the random phase approximation (RPA) correlation potential with a single-pole approximation to model the frequency-dependent polarization function. It captures long-range static and dynamic-frequency effects in the correlation potential, with mean absolute errors of 0.06 eV for EAs of hydrated- and ammoniated-electron clusters with EA values in the range 0.24-1.77 eV. The 1p-XC approximation enables EA estimation with a computational wall-time similar to that of hybrid functionals. The model also provides a compressed-basis, which significantly reduces the rank of higher-level parameter-free one-particle Hamiltonians and further simplifies the computation of EAs. The compressed-basis approach is used to model the hybridization of superatomic molecular states of (C60)2- and (C60)3-, thereby verifying previous model Hamiltonian studies.
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Affiliation(s)
- Ritaj Tyagi
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Vamsee K Voora
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
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5
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Simons J. An environmental impact statement for molecular anions. Phys Chem Chem Phys 2024; 26:1564-1586. [PMID: 38126406 DOI: 10.1039/d3cp04842j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
A molecular anion's (MA's) chemical reactivity and physical behavior can be quite different when it is surrounded by other molecules than when it exists in isolation. This sensitivity to the surrounding environment is especially high for anions because their outermost valence electrons are typically loosely bound and exist in rather spatially diffuse orbitals, allowing even weak intermolecular interactions arising from the environment to have strong effects. This Perspective offers illustrations of such sensitivity for a variety of cases including (i) the effect of solvation on electron binding energies, (ii) how some "well known" anions need to have solvent molecules around to even exist as stable species, (iii) how internal Coulomb repulsions within a multiply charged MA can provide temporary stability toward electron loss, (iv) how MAs arrange themselves spatially near liquid/vapor interfaces in manners that can produce unusual reactivity, (v) how nearby cationic sites can facilitate electron attachment to form a MA site elsewhere, (vi) how internal vibrational or rotational energy can make a MA detach an electron.
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Affiliation(s)
- Jack Simons
- Henry Eyring Center for Theoretical Chemistry, Department of Chemistry, University of Utah, Salt Lake City, UT, 84112, USA.
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6
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Paran GP, Utku C, Jagau TC. On the performance of second-order approximate coupled-cluster singles and doubles methods for non-valence anions. Phys Chem Chem Phys 2024; 26:1809-1818. [PMID: 38168799 PMCID: PMC10793870 DOI: 10.1039/d3cp05923e] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 12/19/2023] [Indexed: 01/05/2024]
Abstract
We investigate the capability of several variants of the second-order approximate coupled-cluster singles and doubles (CC2) method to describe dipole-bound, quadrupole-bound, and correlation-bound molecular anions. The binding energy of anions formed by electron attachment to closed-shell molecules is computed using the electron attachment variant of CC2 (EA-CC2), whereas anions with a closed-shell ground state are treated with the standard CC2 method that preserves the number of particles. We find that EA-CC2 captures the binding energies of dipole-bound radical anions quite well, whereas results for other types of non-valence anions are less reliable. We also test the performance of semi-empirical spin-scaling factors for all types of non-valence anions and observe that the spin-scaled CC2 variants generally do not provide more accurate binding energies for dipole-bound anions, while the binding energies of quadrupole-bound and correlation-bound anions are improved. As exemplary applications of EA-CC2, we investigate the dipole-bound anions of the steroids cortisol, progesterone, and testosterone. In addition, we characterize electron attachment to sym-tetracyanonaphthalene, a molecule that supports five anionic states, two of which can be interpreted as hitherto unobserved π-type quadrupole-bound states.
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Affiliation(s)
| | - Cansu Utku
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
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7
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Kang DH, Cho KH, Kim J, Eun HJ, Rhee YM, Kim SK. Electron-Binding Dynamics of the Dipole-Bound State: Correlation Effect on the Autodetachment Dynamics. J Am Chem Soc 2023; 145:25824-25833. [PMID: 37972034 DOI: 10.1021/jacs.3c10099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
The nature of the electron-binding forces in the dipole-bound states (DBS) of anions is interrogated through experimental and theoretical means by investigating the autodetachment dynamics from DBS Feshbach resonances of ortho-, meta-, and para-bromophenoxide (BrPhO-). Though the charge-dipole electrostatic potential has been widely regarded to be mainly responsible for the electron binding in DBS, the effect of nonclassical electron correlation has been conceived to be quite significant in terms of its static and/or dynamic contributions toward the binding of the excess electron to the neutral core. State-specific real-time autodetachment dynamics observed by picosecond time-resolved photoelectron velocity-map imaging spectroscopy reveal that the autodetachment processes from the DBS Feshbach resonances of BrPhO- anions cannot indeed be rationalized by the conventional charge-dipole potential. Specifically, the autodetachment lifetime is drastically lengthened depending on differently positioned Br-substitution, and this rate change cannot be explained within the framework of Fermi's golden rule based on the charge-dipole assumption. High-level ab initio quantum chemical calculations with EOM-EA-CCSD, which intrinsically takes into account electron correlations, generate more reasonable predictions on the binding energies than density functional theory (DFT) calculations, and semiclassical quantum dynamics simulations based on the EOM-EA-CCSD data excellently predict the trend in the autodetachment rates. These findings illustrate that static and dynamic properties of the excess electron in the DBS are strongly influenced by correlation interactions among electrons in the nonvalence orbital of the dipole-bound electron and highly polarizable valence orbitals of the bromine atom, which, in turn, dictate the interesting chemical fate of exotic anion species.
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Affiliation(s)
- Do Hyung Kang
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Kwang Hyun Cho
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Jinwoo Kim
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Han Jun Eun
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Young Min Rhee
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Sang Kyu Kim
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
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8
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Issler K, Mitrić R, Petersen J. HORTENSIA, a program package for the simulation of nonadiabatic autoionization dynamics in molecules. J Chem Phys 2023; 159:134801. [PMID: 37787145 DOI: 10.1063/5.0167412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 09/11/2023] [Indexed: 10/04/2023] Open
Abstract
We present a program package for the simulation of ultrafast vibration-induced autoionization dynamics in molecular anions in the manifold of the adiabatic anionic states and the discretized ionization continuum. This program, called HORTENSIA (Hopping Real-time Trajectories for Electron-ejection by Nonadiabatic Self-Ionization in Anions), is based on the nonadiabatic surface-hopping methodology, wherein nuclei are propagated as an ensemble along classical trajectories in the quantum-mechanical potential created by the electronic density of the molecular system. The electronic Schrödinger equation is numerically integrated along the trajectory, providing the time evolution of electronic state coefficients, from which switching probabilities into discrete electronic states are determined. In the case of a discretized continuum state, this hopping event is interpreted as the ejection on an electron. The derived diabatic and nonadiabatic couplings in the time-dependent electronic Schrödinger equation are calculated from anionic and neutral wavefunctions obtained from quantum-chemical calculations with commercially available program packages interfaced with our program. Based on this methodology, we demonstrate the simulation of autoionization electron kinetic energy spectra that are both time- and angle-resolved. In addition, the program yields data that can be interpreted easily with respect to geometric characteristics, such as bonding distances and angles, which facilitate the detection of molecular configurations important for the autoionization process. Furthermore, several useful extensions are included, namely, tools for the generation of initial conditions and input files as well as for the evaluation of output files, all of this both through console commands and a graphical user interface.
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Affiliation(s)
- Kevin Issler
- Julius-Maximilians-Universität Würzburg, Institut für Physikalische und Theoretische Chemie, Emil-Fischer-Str. 42, 97074 Würzburg, Germany
| | - Roland Mitrić
- Julius-Maximilians-Universität Würzburg, Institut für Physikalische und Theoretische Chemie, Emil-Fischer-Str. 42, 97074 Würzburg, Germany
| | - Jens Petersen
- Julius-Maximilians-Universität Würzburg, Institut für Physikalische und Theoretische Chemie, Emil-Fischer-Str. 42, 97074 Würzburg, Germany
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9
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Zhang YR, Yuan DF, Wang LS. Probing Dipole-Bound States Using Photodetachment Spectroscopy and Resonant Photoelectron Imaging of Cryogenically Cooled Anions. J Phys Chem Lett 2023; 14:7368-7381. [PMID: 37565830 DOI: 10.1021/acs.jpclett.3c01994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Molecular anions with polar neutral cores can support highly diffuse dipole-bound states below their detachment thresholds due to the long-range charge-dipole interaction. Such nonvalence states constitute a special class of excited electronic states for anions and were observed in early photodetachment experiments to measure the electron affinities of organic radicals. Recent experimental advances, in particular, the ability to create cold anions using a cryogenically cooled Paul trap, have allowed the investigation of dipole-bound excited states at a new level. For the first time, the zero-point level of dipole-bound excited states can be observed via resonant two-photon detachment, and resonant photoelectron spectroscopy can be performed via the above-threshold vibrational levels (Feshbach resonances) of the dipole-bound states. This Perspective describes recent progress in the investigation of dipole-bound states in the authors' lab using an electrospray photoelectron spectroscopy apparatus equipped with a cryogenically cooled Paul trap and high-resolution photoelectron imaging.
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Affiliation(s)
- Yue-Rou Zhang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Dao-Fu Yuan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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10
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Zhang YR, Yuan DF, Qian CH, Zhu GZ, Wang LS. Role of Polarization Interactions in the Formation of Dipole-Bound States. J Am Chem Soc 2023. [PMID: 37368495 DOI: 10.1021/jacs.3c04740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2023]
Abstract
Even though there is a critical dipole moment required to support a dipole-bound state (DBS), how molecular polarizability may influence the formation of DBSs is not well understood. Pyrrolide, indolide, and carbazolide provide an ideal set of anions to systematically examine the role of polarization interactions in the formation of DBSs. Here, we report an investigation of carbazolide using cryogenic photodetachment spectroscopy and high-resolution photoelectron spectroscopy (PES). A polarization-assisted DBS is observed at 20 cm-1 below the detachment threshold for carbazolide, even though the carbazolyl neutral core has a dipole moment (2.2 D) smaller than the empirical critical value (2.5 D) to support a dipole-bound state. Photodetachment spectroscopy reveals nine vibrational Feshbach resonances of the DBS, as well as three intense and broad shape resonances. The electron affinity of carbazolyl is measured accurately to be 2.5653 ± 0.0004 eV (20,691 ± 3 cm-1). The combination of photodetachment spectroscopy and resonant PES allows fundamental frequencies for 14 vibrational modes of carbazolyl to be measured. The three shape resonances are due to above-threshold excitation to the three low-lying electronic states (S1-S3) of carbazolide. Resonant PES of the shape resonances is dominated by autodetachment processes. Ultrafast relaxation from the S2 and S3 states to S1 is observed, resulting in constant kinetic energy features in the resonant PES. The current study provides decisive information about the role that polarization plays in the formation of DBSs, as well as rich spectroscopic information about the carbazolide anion and the carbazolyl radical.
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Affiliation(s)
- Yue-Rou Zhang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Dao-Fu Yuan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Chen-Hui Qian
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Guo-Zhu Zhu
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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11
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Bandyopadhyay P, Sadhukhan M. Modeling coarse-grained van der Waals interactions using dipole-coupled anisotropic quantum Drude oscillators. J Comput Chem 2023; 44:1164-1173. [PMID: 36645104 DOI: 10.1002/jcc.27073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 12/21/2022] [Accepted: 12/23/2022] [Indexed: 01/17/2023]
Abstract
The Quantum Drude Oscillator (QDO) model is a promising candidate for accurately calculating the van der Waals (vdW) interaction. Anisotropic QDO models have recently been used to represent quantum fluctuations of molecular fragments rather than that of single atoms. While this model promises accurate calculation of vdW energy, there is significant room for improvements, such as incorporating a proper fragmentation method, higher-order dispersion corrections, and so forth. The present work attempts to gauge dipole-dipole interactions' ability without fragmentation. A suitable anisotropic damping function is also introduced to work with anisotropic QDO. This revised model accurately predicts the binding energies of vdW complexes for most of the systems considered. This work indicates the limit of dipole approximation for an anisotropic QDO-based model.
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Affiliation(s)
| | - Mainak Sadhukhan
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, India
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12
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Abstract
This Perspective attempts to shed light on developments in the theoretical and experimental study of molecular anions highlighting more recent workers in the field. The species I discuss include (i) valence-bound (singly and multiply charged) anions including atmospheric, catalytic, superhalogen, interfacial, and more; (ii) dipole- and correlation-bound anions including their role as doorways to other states and their appearance "in space", and (iii) metastable anions focusing on tools needed for their theoretical treatment. I also briefly discuss angular distributions of photodetached electrons and their growing utilization in experiments and theory. A recurring theme is the dependence of electron binding energies (EBEs) on the surrounding environment. Some anions that are nonexistent as isolated species evolve to be stable but with small EBEs when weakly solvated (e.g., as in a cluster or at an air-solvent interface). Others existing in isolation only as metastable species become stable when the underlying molecular framework contains one or more positively charged group (e.g., protonated side chains in a peptide) that generates a stabilizing Coulomb potential. On the other hand, a destabilizing Coulomb potential between/among negative sites in a multiply charged anion decreases the EBEs of each such site and generates a repulsive Coulomb barrier that can affect stability.
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Affiliation(s)
- Jack Simons
- Henry Eyring Center for Theoretical Chemistry, Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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13
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Abstract
Weakly bound non-valence anions are molecular systems where the excess electron stabilizes in a very diffuse orbital whose size, shape, and binding energy (∼1-100 meV) are governed by the long-range electrostatic potential of the molecule. Its binding energy comes mainly from charge-dipole or charge-multipole interactions or dispersion forces. While highly correlated methods, like coupled cluster methods, are considered to be the state of the art for describing anionic systems, especially when the electron lies in a very diffuse orbital, we consider here the possibility to use DFT-based calculations. In such molecular anions, the outer electron experiences long-range exchange and correlation interactions. We show that DFT can describe long-range bound states provided that a correct asymptotic exchange and correlation potential is used, namely, that from a range-separated hybrid functional. This opens an alternative to the computationally demanding highly correlated method calculations. It is also suggested that the study of weakly bound anions could help in the construction of new DFT potentials to study systems where nonlocal effects are significant.
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Affiliation(s)
- Guillaume Thiam
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, UMR5306, F-69622 Villeurbanne, France
| | - Franck Rabilloud
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, UMR5306, F-69622 Villeurbanne, France
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14
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Luxford TFM, Fedor J, Kočišek J. Electron Energy Loss Processes in Methyl Methacrylate: Excitation and Bond Breaking. J Phys Chem A 2023; 127:2731-2741. [PMID: 36930039 PMCID: PMC10068740 DOI: 10.1021/acs.jpca.2c09077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
Details of electron-induced chemistry of methyl methacrylate (MMA) upon complexation are revealed by combining gas-phase 2D electron energy loss spectroscopy with electron attachment spectroscopy of isolated MMA and its clusters. We show that even though isolated MMA does not form stable parent anions, it efficiently thermalizes the incident electrons via intramolecular vibrational redistribution, leading to autodetachment of slow electrons. This autodetachment channel is reduced in clusters due to intermolecular energy transfer and stabilization of parent molecular anions. Bond breaking via dissociative electron attachment leads to an extensive range of anion products. The dominant OCH3- channel is accessible via core-excited resonances with threshold above 5 eV, despite the estimated thermodynamic threshold below 3 eV. This changes in clusters, where MnOCH3- anions are observed in a lower-lying resonance due to neutral dissociation of the 1(n, π*) state and electron self-scavenging. The present findings have implications for electron-induced chemistry in lithography with poly(methyl methacrylate).
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Affiliation(s)
- Thomas F M Luxford
- J. Heyrovský Institute of Physical Chemistry of CAS, Dolejškova 3, 18223 Prague, Czech Republic
| | - Juraj Fedor
- J. Heyrovský Institute of Physical Chemistry of CAS, Dolejškova 3, 18223 Prague, Czech Republic
| | - Jaroslav Kočišek
- J. Heyrovský Institute of Physical Chemistry of CAS, Dolejškova 3, 18223 Prague, Czech Republic
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15
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Yuan DF, Liu Y, Zhang YR, Wang LS. Observation of a Polarization-Assisted Dipole-Bound State. J Am Chem Soc 2023; 145:5512-5522. [PMID: 36809761 DOI: 10.1021/jacs.3c00246] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
The critical dipole moment to bind an electron was empirically determined to be 2.5 debye, even though smaller values were predicted theoretically. Herein, we report the first observation of a polarization-assisted dipole-bound state (DBS) for a molecule with a dipole moment below 2.5 debye. Photoelectron and photodetachment spectroscopies are conducted for cryogenically cooled indolide anions, where the neutral indolyl radical has a dipole moment of 2.4 debye. The photodetachment experiment reveals a DBS only 6 cm-1 below the detachment threshold along with sharp vibrational Feshbach resonances. Rotational profiles are observed for all of the Feshbach resonances, which are found to have surprisingly narrow linewidths and long autodetachment lifetimes attributed to weak coupling between vibrational motions and the nearly free dipole-bound electron. Calculations suggest that the observed DBS has π-symmetry stabilized by the strong anisotropic polarizability of indolyl.
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Affiliation(s)
- Dao-Fu Yuan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Yuan Liu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Yue-Rou Zhang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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16
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Ouyang L, Lin H, Zhuang P, Shao Y, Khosravifarsani M, Guérin B, Zheng Y, Sanche L. DNA radiosensitization by terpyridine-platinum: damage induced by 5 and 10 eV transient anions. NANOSCALE 2023; 15:3230-3242. [PMID: 36722902 DOI: 10.1039/d2nr05403e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Chemoradiation therapy (CRT), which combines a chemotherapeutic drug with ionizing radiation (IR), is the most common cancer treatment. At the molecular level, the binding of Pt-drugs to DNA sensitizes cancer cells to IR, mostly by increasing the damage induced by secondary low-energy (0-20 eV) electrons (LEEs). We investigate such enhancements by binding terpyridine-platinum (Tpy-Pt) to supercoiled plasmid DNA. Fifteen nanometer thick films of Tpy-Pt-DNA complexes in a molar ratio of 5 : 1 were irradiated with monoenergetic electrons of 5 and 10 eV, which principally attach to the DNA bases to form transient anions (TAs) decaying into a multitude of bond-breaking channels. At both energies, the effective yields of crosslinks (CLs), base damage (BD) related CLs, single and double strand breaks (SSBs and DSBs), non-DSB-cluster lesions, loss of supercoiled configuration and base lesions are 6.5 ± 1.5, 8.8± 3.0, 88 ± 11, 5.3 ± 1.3, 9.6 ± 2.2, 106 ± 17, 189 ± 31 × 10-15 per electron per molecule, and 11.9 ± 2.6, 19.9 ± 4.4, 128 ± 18, 7.7 ± 3.0, 13.4 ± 3.9, 144 ± 19, 229 ± 42 × 10-15 per electron per molecule, respectively. DNA damage increased 1.2-4.2-fold due to Tpy-Pt, the highest being for BD-related CLs. These enhancements are slightly higher than those obtained by the conventional Pt-drugs cisplatin, carboplatin and oxaliplatin, apart from BD-related CLs, which are about 3 times higher. Enhancements are related to the strong perturbation of the DNA helix by Tpy-Pt, its high dipole moment and its favorable binding to guanine (G), all of which increase bond-breaking via TA formation. In CRT, Tpy-Pt could considerably enhance crosslinking within genomic DNA and between DNA and other components of the nucleus, causing roadblocks to replication and transcription, particularly within telomeres, where it binds preferentially within G-quadruplexes.
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Affiliation(s)
- Liangde Ouyang
- State Key Laboratory of Photocatalysis on Energy and Environment, Faculty of Chemistry, Fuzhou University, Fuzhou 350116, P.R. China
| | - Hong Lin
- State Key Laboratory of Photocatalysis on Energy and Environment, Faculty of Chemistry, Fuzhou University, Fuzhou 350116, P.R. China
| | - Puxiang Zhuang
- State Key Laboratory of Photocatalysis on Energy and Environment, Faculty of Chemistry, Fuzhou University, Fuzhou 350116, P.R. China
| | - Yu Shao
- State Key Laboratory of Photocatalysis on Energy and Environment, Faculty of Chemistry, Fuzhou University, Fuzhou 350116, P.R. China
| | - Meysam Khosravifarsani
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada J1H 5N4.
| | - Brigitte Guérin
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada J1H 5N4.
| | - Yi Zheng
- State Key Laboratory of Photocatalysis on Energy and Environment, Faculty of Chemistry, Fuzhou University, Fuzhou 350116, P.R. China
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada J1H 5N4.
| | - Léon Sanche
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada J1H 5N4.
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17
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Jarrold CC. Probing Anion-Molecule Complexes of Atmospheric Relevance Using Anion Photoelectron Detachment Spectroscopy. ACS PHYSICAL CHEMISTRY AU 2022; 3:17-29. [PMID: 36718261 PMCID: PMC9881448 DOI: 10.1021/acsphyschemau.2c00060] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 01/01/2023]
Abstract
Bimolecular reaction and collision complexes that drive atmospheric chemistry and contribute to the absorption of solar radiation are fleeting and therefore inherently challenging to study experimentally. Furthermore, primary anions in the troposphere are short lived because of a complicated web of reactions and complex formation they undergo, making details of their early fate elusive. In this perspective, the experimental approach of photodetaching mass-selected anion-molecule complexes or complex anions, which prepares neutrals in various vibronic states, is surveyed. Specifically, the application of anion photoelectron spectroscopy along with photoelectron-photofragment coincidence spectroscopy toward the study of collision complexes, complex anions in which a partial covalent bond is formed, and radical bimolecular reaction complexes, with relevance in tropospheric chemistry, will be highlighted.
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18
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Zhang YR, Yuan DF, Wang LS. Investigation of the Electronic and Vibrational Structures of the 2-Furanyloxy Radical Using Photoelectron Imaging and Photodetachment Spectroscopy via the Dipole-Bound State of the 2-Furanyloxide Anion. J Phys Chem Lett 2022; 13:11481-11488. [PMID: 36469423 DOI: 10.1021/acs.jpclett.2c03382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The 2-furanyloxy radical is an important chemical reaction intermediate in the combustion of biofuels and aromatic compounds. We report an investigation of its electronic and vibrational structures using photoelectron and photodetachment spectroscopy and resonant photoelectron imaging (PEI) of cryogenically cooled 2-furanyloxide anion. The electron affinity of 2-furanyloxy is measured to be 1.7573(8) eV. Two excited electronic states are observed at excitation energies of 2.14 and 2.82 eV above the ground state. Photodetachment spectroscopy reveals a dipole-bound state 0.0143 eV below the detachment threshold and 25 vibrational Feshbach resonances for the 2-furanyloxide anion. The combination of photodetachment spectroscopy and resonant PEI yields frequencies for 18 out of a total of 21 vibrational modes for the 2-furanyloxy radical, including all six of its bending modes. The rich electronic and vibrational information will be valuable for further understanding the role of 2-furanyloxy as a key reaction intermediate of combustion and atmospheric interests.
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Affiliation(s)
- Yue-Rou Zhang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Dao-Fu Yuan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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19
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Abstract
In this work, it is demonstrated that a simple analytical expression, (A/R2) exp(-B/μ-μcr), where μ is the dipole moment, μcr is the critical dipole moment, and A and B are constants, accurately describes the binding energy of an electron in the field of a finite fixed dipole over a wide range of dipole moments. It is also demonstrated that this expression provides an accurate fit to the experimental electron binding energies for the dipole-bound anions of a series of phenoxy radicals. A simple extension of this expression is found to be applicable when the dipole model is extended to include short-range repulsion and polarization interactions.
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Affiliation(s)
- S Slimak
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - K D Jordan
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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20
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Kang DH, Kim J, Eun HJ, Kim SK. State-Specific Chemical Dynamics of the Nonvalence Bound State of the Molecular Anions. Acc Chem Res 2022; 55:3032-3042. [PMID: 36206486 DOI: 10.1021/acs.accounts.2c00512] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Nonvalence bound states (NBS) are anionic states where the excess electron is extremely loosely bound to the neutral core through long-range potentials. In contrast to the valence orbitals of which the electron occupancy determines the molecular structure, as well as the chemical reactivity, the nonvalence orbital is quite diffuse and located far from the neutral core. The NBS can be classified into the dipole-bound state (DBS), quadruple-bound state (QBS), or correlation-bound state (CBS) according to the nature of the electron-neutral interaction, although their interaction potentials may cooperatively contribute. The NBS is ubiquitous in nature and has the strong implications in atmospheric, interstellar, or biological chemistry. Accordingly, NBS has long been conceived to play the role of the doorway into the formation of a stable anion or dissociative electron attachment (DEA). Despite intensive and extensive studies, however, the quantum-mechanical nature of NBS is still far from being thorough understanding. Herein, we describe a new aspect of state-specific NBS-mediated chemical dynamics, which has been revealed through a series of recent studies by our group. We have employed picosecond time-resolved pump-probe spectroscopy combined with cryogenically cooled ion trap and velocity-map imaging techniques to study closed-shell anions generated by electrospray ionization. DBS vibrational Feshbach resonances are prepared by the optical excitation of phenoxide, for instance, and their individual lifetimes have been precisely measured in a state-specific manner to reveal the strong mode-dependency of the autodetachment rate. Fermi's golden rule turns out to be extremely useful for a rational explanation of the experiment, although the more sophisticated theoretical model is desirable for the more quantitative analysis. For the DBS of para-chlorophenoxide or para-bromophenoxide where the polarizability of neutral core is substantial, the Fermi's golden rule based on the charge-dipole potential needs to be significantly modified to include the correlation effects to explain the exceptionally slow autodetachment rates. For the QBS of 4-cyanophenoxide, the mode-specific behavior of the quadrupole ellipsoid tensor explains the strong mode-dependent autodetachment rate. Meanwhile, the nonadiabatic transition of the excess electron into the valence orbital can result in stable anion formation or immediate chemical bond rupture. In the DBS of ortho-, meta-, or para-iodophenoxide, the transformation of the loosely bound excess electron into the πσ* antibonding orbital occurs to give I- as a final fragment. The fragmentation mediated by DBS occurs competitively with the concomitant autodetachment, paving a new way of the reaction control by tuning the quantum-mechanical nature of the DBS Feshbach resonance. This experimental observation provides the foremost evidence for the dynamic role of the DBS as a doorway into anion chemistry, such as DEA. The ponderomotive force on the electron in the nonvalence orbital has been demonstrated for the first time in a strong optical field, giving great promise for the manipulation of polyatomic molecules in terms of the spatial location, as well as the AC-Stark control of the chemical reaction.
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Affiliation(s)
- Do Hyung Kang
- Department of Chemistry, KAIST, Daejeon34141, Republic of Korea
| | - Jinwoo Kim
- Department of Chemistry, KAIST, Daejeon34141, Republic of Korea
| | - Han Jun Eun
- Department of Chemistry, KAIST, Daejeon34141, Republic of Korea
| | - Sang Kyu Kim
- Department of Chemistry, KAIST, Daejeon34141, Republic of Korea
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21
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Lu Y, Tang R, Zhang R, Ning C. Probing Isomerization Dynamics via a Dipole-Bound State. J Phys Chem Lett 2022; 13:8711-8716. [PMID: 36094393 DOI: 10.1021/acs.jpclett.2c02348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The observation of molecular isomerization dynamics is a long-standing goal in physical chemistry. The loosely bound electron in a dipole-bound state (DBS) can be a messenger for probing the isomerization of the neutral core. Here we study the isomerization dynamics of the salt dimer (NaCl)2 from linear to rhombic via a DBS using cryogenic photoelectron spectroscopy in combination with ab initio calculations. Although the energy level of the DBS is below the electron affinity of the linear (NaCl)2, (NaCl)2- in its DBS can autodetach due to the linear-to-rhombic isomerization. (NaCl)2- in the ground DBS has a relatively long lifetime of a few nanoseconds due to the quantum tunneling through a potential barrier during the transformation from linear to rhombic. In contrast, the vibrationally excited DBS has a much shorter lifetime on the order of picoseconds. The energy distribution of autodetachment electrons has an unexpected characteristic of the thermionic emission.
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Affiliation(s)
- Yuzhu Lu
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China
| | - Rulin Tang
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China
| | - Rui Zhang
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China
| | - Chuangang Ning
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing, 100084, China
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22
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Ru B, Hart CA, Mabbs R, Gozem S, Krylov AI, Sanov A. Dipole effects in the photoelectron angular distributions of the sulfur monoxide anion. Phys Chem Chem Phys 2022; 24:23367-23381. [PMID: 36129043 DOI: 10.1039/d2cp03337b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoelectron angular distributions (PADs) in SO- photodetachment using linearly polarized 355 nm (3.49 eV), 532 nm (2.33 eV), and 611 nm (2.03 eV) light were investigated via photoelectron imaging spectroscopy. The measurements at 532 and 611 nm access the X3Σ- and a1Δ electronic states of SO, whereas the measurements at 355 nm also access the b1Σ+ state. In aggregate, the photoelectron anisotropy parameter values follow the general trend with respect to electron kinetic energy (eKE) expected for π*-orbital photodetachment. The trend is similar to O2-, but the minimum of the SO- curve is shifted to smaller eKE. This shift is mainly attributed to the exit-channel interactions of the departing electron with the dipole moment of the neutral SO core, rather than the differing shapes of the SO- and O2- molecular orbitals. Of the several ab initio models considered, two approaches yield good agreement with the experiment: one representing the departing electron as a superposition of eigenfunctions of a point dipole-field Hamiltonian, and another describing the outgoing electron in terms of Coulomb waves originating from two separated charge centers, with a partial positive charge on the sulfur and an equal negative charge on the oxygen. These fundamentally related approaches support the conclusion that electron-dipole interactions in the exit channel of SO- photodetachment play an important role in shaping the PADs. While a similar conclusion was previously reached for photodetachment from σ orbitals of CN- (Hart, Lyle, Spellberg, Krylov, Mabbs, J. Phys. Chem. Lett., 2021, 12, 10086-10092), the present work includes the first extension of the dipole-field model to detachment from π* orbitals.
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Affiliation(s)
- Beverly Ru
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA.
| | - C Annie Hart
- Department of Chemistry, Washington University, Saint Louis, MO 63130, USA
| | - Richard Mabbs
- Department of Chemistry, Washington University, Saint Louis, MO 63130, USA
| | - Samer Gozem
- Department of Chemistry, Georgia State University, Atlanta, GA 30302, USA
| | - Anna I Krylov
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA
| | - Andrei Sanov
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA.
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23
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Yuan DF, Zhang YR, Wang LS. Dipole-Bound State, Photodetachment Spectroscopy, and Resonant Photoelectron Imaging of Cryogenically-Cooled 2-Cyanopyrrolide. J Phys Chem A 2022; 126:6416-6428. [PMID: 36097646 DOI: 10.1021/acs.jpca.2c04405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Valence-bound anions with polar neutral cores can have diffuse dipole-bound excited states just below the electron detachment threshold. Because of the similarity in geometry and vibrational frequencies between the dipole-bound states (DBSs) and the corresponding neutrals, DBSs have been exploited as intermediate states to conduct resonant photoelectron spectroscopy (PES), resulting in highly non-Franck-Condon photoelectron spectra via vibrational autodetachment and providing much richer vibrational information than conventional PES. Here, we report a photodetachment and high-resolution photoelectron imaging study of the 2-cyanopyrrolide anion, cooled in a cryogenic ion trap. The electron affinity of the 2-cyanopyrrolyl radical is measured to be 3.0981 ± 0.0006 eV (24 988 ± 5 cm-1). A DBS is observed for 2-cyanopyrrolide at 240 cm-1 below its detachment threshold using photodetachment spectroscopy. Twenty-three above-threshold vibrational resonances (Feshbach resonances) of the DBS are observed. Resonant PES is conducted at each Feshbach resonance, yielding a wealth of vibrational information about the 2-cyanopyrrolyl radical. Resonant two-photon PES confirms the s-like dipole-bound orbital and reveals a relatively long lifetime of the bound zero-point level of the DBS. Fundamental frequencies for 19 vibrational modes (out of a total of 24) are obtained for the cyanopyrrolyl radical, including six out-of-plane modes. The current work provides important spectroscopic information about 2-cyanopyrrolyl, which should be valuable for the study of this radical in combustion or astronomical environments.
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Affiliation(s)
- Dao-Fu Yuan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Yue-Rou Zhang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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24
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Kang DH, Kim J, Eun HJ, Kim SK. Experimental Observation of the Resonant Doorways to Anion Chemistry: Dynamic Role of Dipole-Bound Feshbach Resonances in Dissociative Electron Attachment. J Am Chem Soc 2022; 144:16077-16085. [PMID: 35973092 DOI: 10.1021/jacs.2c06334] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Anion chemical dynamics of autodetachment and fragmentation mediated by the dipole-bound state (DBS) have been thoroughly investigated in a state-specific way by employing the picosecond time-resolved or the nanosecond frequency-resolved spectroscopy combined with the cryogenically cooled ion trap and velocity-map imaging techniques. For the ortho-, meta-, or para-iodophenoxide anion (o-, m-, or p-IPhO-), the C-I bond rupture occurs via the nonadiabatic transition from the DBS to the nearby valence-bound states (VBS) of the anion where the vibronic coupling into the S1 (πσ*) state (repulsive along the C-I bond extension coordinate) should be largely responsible. Dynamic details are governed by the isomer-specific nature of the potential energy surfaces in the vicinity of the DBS-VBS curve crossings, as manifested in the huge different chemical reactivity of o-, m-, or p-IPhO-. It is confirmed here that the C-I bond dissociation is mediated by DBS resonances, providing the foremost evidence that the metastable DBS plays the critical role as the doorway into the anion chemistry especially of the dissociative electron attachment (DEA). The fragmentation channel is dominant when it is mediated by the DBS resonances located below the electron-affinity (EA) threshold, whereas it is kinetically adjusted by the competitive autodetachment when the DBS resonances above EA convey the electron to the valence orbitals. The product yield of the C-I bond cleavage is strongly mode-dependent as the rate of the concomitant autodetachment is much influenced by the characteristics of the individual vibrational modes, paving a new way of the reaction control of the anion chemistry.
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Affiliation(s)
- Do Hyung Kang
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Jinwoo Kim
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Han Jun Eun
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Sang Kyu Kim
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
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25
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Brzeski J, Jordan KD. Non-Valence Anions of Pyridine and the Diazines. J Phys Chem A 2022; 126:5310-5313. [PMID: 35920853 DOI: 10.1021/acs.jpca.2c04040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The dipole-bound anions of pyridine, pyridazine, and pyrimidine are characterized using equation of motion coupled cluster singles and doubles calculations. These calculations predict that the anions of pyridine, pyrimidine and pyridazine are bound in the Born-Oppenheimer approximation by 0.05, 0.8, and 19.0 meV, respectively. The binding energies of pyrimidine and pyridazine are large enough that the anions will remain bound even when allowing for corrections to the Born-Oppenheimer approximation, while that of pyridine is a borderline case. We were unable to find a stable non-valence correlation-bound anion for pyrazine, which has a zero dipole moment.
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Affiliation(s)
- Jakub Brzeski
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15218, United States.,Department of Bioinorganic Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Kenneth D Jordan
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15218, United States
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26
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Anusiewicz I, Skurski P, Simons J. Finding Valence Antibonding Levels while Avoiding Rydberg, Pseudo-continuum, and Dipole-Bound Orbitals. J Am Chem Soc 2022; 144:11348-11363. [PMID: 35699697 DOI: 10.1021/jacs.2c03422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Electronic structure methods are now widely used to assist in the interpretation of many varieties of experimental data. The energies and physical characteristics (e.g., sizes, shapes, and spatial localization) of valence antibonding π* and σ* orbitals play key roles in a variety of chemical processes including photochemical reactions and electron attachment reductions and are used in Woodward-Hoffmann-type analyses to probe reaction energy barriers and energy surface intersections leading to internal conversion or intersystem crossings. One's ability to properly populate such valence antibonding orbitals within electronic structure calculations is often hindered by the presence of other molecular orbitals having similar energies. These intruding orbitals can be of Rydberg, pseudo-continuum, or dipole-bound characteristic. This article shows how, within the most widely available electronic structure codes, one can avoid the pitfalls presented by these intruding orbitals to properly populate a valence π* or σ* orbital and how to subsequently use that orbital in a calculation that includes electron correlation effects and thereby offers the possibility of chemically useful precision. Special emphasis is given to cases in which the electronic state is metastable.
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Affiliation(s)
- Iwona Anusiewicz
- Laboratory of Quantum Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Piotr Skurski
- Laboratory of Quantum Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Jack Simons
- Henry Eyring Center for Theoretical Chemistry, Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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27
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Abstract
Polar molecules can bind an electron in a diffuse orbital due to the charge-dipole interaction. Electronic excited states of polar molecules can also bind an electron to form core-excited dipole-bound states (DBSs), analogous to core-excited Rydberg states. However, core-excited DBSs have not been observed because of the complicated electronic structure of molecular systems. Here, we report the observation of a core-excited DBS in the pyrazolide anion as a result of the favorable electronic structure of the neutral pyrazolyl core, which has a low-lying excited state (Ã2B1) only 266 cm-1 above its ground state (X̃2A2). The binding energy of the DBS associated with the ground state is measured to be 221 cm-1, while that of the core-excited DBS is 276 cm-1, which is still a bound state relative to the detachment threshold. Vibrational Feshbach resonances are observed for both DBSs, and their autodetachment behaviors are studied by resonant photoelectron imaging.
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Affiliation(s)
- Yue-Rou Zhang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Dao-Fu Yuan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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28
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Kang DH, Kim J, Kim SK. Dynamic role of the correlation effect revealed in the exceptionally slow autodetachment rates of the vibrational Feshbach resonances in the dipole-bound state. Chem Sci 2022; 13:2714-2720. [PMID: 35356673 PMCID: PMC8890126 DOI: 10.1039/d1sc05481c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 02/03/2022] [Indexed: 11/21/2022] Open
Abstract
Real-time autodetachment dynamics of the loosely bound excess electron from the vibrational Feshbach resonances of the dipole-bound states (DBS) of 4-bromophonoxide (4-BrPhO-) and 4-chlorophenoxide (4-ClPhO-) anions have been thoroughly investigated. The state-specific autodetachment rate measurements obtained by the picosecond time-resolved pump-probe method on the cryogenically cooled anions exhibit an exceptionally long lifetime (τ) of ∼823 ± 156 ps for the 11'1 vibrational mode of the 4-BrPhO- DBS. Strong mode-dependency in the wide dynamic range has also been found, giving τ ∼ 5.3 ps for the 10'1 mode, for instance. Though it is nontrivial to get the state-specific rates for the 4-ClPhO- DBS, the average autodetachment lifetime of the 19'120'1/11'1 mode has been estimated to be ∼548 ± 108 ps. Observation of these exceptionally slow autodetachment rates of vibrational Feshbach resonances strongly indicates that the correlation effect may play a significant role in the DBS photodetachment dynamics. Fermi's golden rule has been invoked so that the correlation effect is taken into account in the form of the interaction between the charge and the induced dipole where the latter is given by the polarizable counterparts of the electron-rich halogenated compound and the diffuse non-valence electron. This report suggests that one may measure, from the real-time autodetachment dynamics, the extent of the correlation effect contribution to the stabilization and/or dynamics of the excess non-valence electron among many different types of long-range interactions of the DBS.
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Affiliation(s)
- Do Hyung Kang
- Department of Chemistry, KAIST Daejeon 34141 Republic of Korea
| | - Jinwoo Kim
- Department of Chemistry, KAIST Daejeon 34141 Republic of Korea
| | - Sang Kyu Kim
- Department of Chemistry, KAIST Daejeon 34141 Republic of Korea
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29
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Associative detachment in anion-atom reactions involving a dipole-bound electron. Nat Commun 2022; 13:818. [PMID: 35145072 PMCID: PMC8831523 DOI: 10.1038/s41467-022-28382-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 12/27/2021] [Indexed: 11/21/2022] Open
Abstract
Associative electronic detachment (AED) between anions and neutral atoms leads to the detachment of the anion’s electron resulting in the formation of a neutral molecule. It plays a key role in chemical reaction networks, like the interstellar medium, the Earth’s ionosphere and biochemical processes. Here, a class of AED involving a closed-shell anion (OH−) and alkali atoms (rubidium) is investigated by precisely controlling the fraction of electronically excited rubidium. Reaction with the ground state atom gives rise to a stable intermediate complex with an electron solely bound via dipolar forces. The stability of the complex is governed by the subtle interplay of diabatic and adiabatic couplings into the autodetachment manifold. The measured rate coefficients are in good agreement with ab initio calculations, revealing pronounced steric effects. For excited state rubidium, however, a lower reaction rate is observed, indicating dynamical stabilization processes suppressing the coupling into the autodetachment region. Our work provides a stringent test of ab initio calculations on anion-neutral collisions and constitutes a generic, conceptual framework for understanding electronic state dependent dynamics in AEDs. Associative electronic detachment (AED) reactions of anions play a key role in many natural processes. Here, Hassan and colleagues investigate AED reactions between hydroxyl anions and ultracold rubidium atoms in a hybrid atom-ion trap, revealing different dynamics for collisions with ground and electronically excited state rubidium.
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30
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Valence-, Dipole- and Quadropole-Bound Electronically Excited States of Closed-Shell Anions Formed by Deprotonation of Cyano- and Ethynyl-Disubstituted Polycyclic Aromatic Hydrocarbons. CHEMISTRY 2022. [DOI: 10.3390/chemistry4010004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Dicyano-functionalized benzene and naphthalene anion derivatives exhibit a relatively rich population of electronically excited states in stark contrast to many assumptions regarding the photophysics of anions in general. The present work has quantum chemically analyzed the potential electronically excited states of closed-shell anions created by replacing hydrogen atoms with valence-bound lone pairs in benzene and naphthalene difunctionalized with combinations of -CN and -C2H. Dicyanobenzene anion derivatives can exhibit dipole-bound excited states as long as the cyano groups are not in para position to one another. This also extends to cyanoethynylbenzene anions as well as deprotonated dicyano- and cyanoethynylnaphthalene anion derivatives. Diethynyl functionalization is less consistent. While large dipole moments are created in some cases for deprotonation on the -C2H group itself, the presence of electronically excited states beyond those that are dipole-bound is less consistent. Beyond these general trends, 2-dicyanonaphthalene-34 gives strong indication for exhibiting a quadrupole-bound excited state, and the 1-cyanoethynylnaphthalene-29 and -36 anion derivatives are shown to possess as many as two valence-bound excited states and one dipole-bound excited state. These photophysical properties may have an influence on regions where polycyclic aromatic hydrocarbons are known to exist such as in various astrochemical environments or even in combustion flames.
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31
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Yuan DF, Zhang YR, Qian CH, Wang LS. Resonant two-photon photoelectron imaging and adiabatic detachment processes from bound vibrational levels of dipole-bound states. Phys Chem Chem Phys 2022; 24:1380-1389. [PMID: 34981094 DOI: 10.1039/d1cp05219e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Anions cannot have Rydberg states, but anions with polar neutral cores can support highly diffuse dipole-bound states (DBSs) as a class of interesting electronically excited states below the electron detachment threshold. The binding energies of DBSs are extremely small, ranging from a few to few hundred wavenumbers and generally cannot support bound vibrational levels below the detachment threshold. Thus, vibrational excitations in the DBS are usually above the electron detachment threshold and they have been used to conduct resonant photoelectron spectroscopy, which is dominated by state-specific autodetachment. Here we report an investigation of a cryogenically-cooled complex anion, the enantiopure (R)-(-)-1-(9-anthryl)-2,2,2-trifluoroethanolate (R-TFAE-). The neutral R-TFAE radical is relatively complex and highly polar with a non-planar structure (C1 symmetry). Photodetachment spectroscopy reveals a DBS 209 cm-1 below the detachment threshold of R-TFAE- and seven bound and eight above-threshold vibrational levels of the DBS. Resonant two-photon detachment (R2PD) via the bound vibrational levels of the DBS exhibits strictly adiabatic photodetachment behaviors by the second photon, in which the vibrational energies in the DBS are carried to the neutral final states, because of the parallel potential energy surfaces of the DBS and the corresponding neutral ground electronic state. Relaxation processes from the bound DBS levels to the ground and low-lying electronically excited states of R-TFAE- are also observed in the R2PD photoelectron spectra. The combination of photodetachment and resonant photoelectron spectroscopy yields frequencies for eight vibrational modes of the R-TFAE radical.
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Affiliation(s)
- Dao-Fu Yuan
- Department of Chemsitry, Brown University, Providence, RI 02912, USA.
| | - Yue-Rou Zhang
- Department of Chemsitry, Brown University, Providence, RI 02912, USA.
| | - Chen-Hui Qian
- Department of Chemsitry, Brown University, Providence, RI 02912, USA.
| | - Lai-Sheng Wang
- Department of Chemsitry, Brown University, Providence, RI 02912, USA.
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32
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Bandyopadhyay P, Priya P, Sadhukhan M. A simple fragment-based method for van der Waals corrections over density functional theory. Phys Chem Chem Phys 2022; 24:8508-8518. [DOI: 10.1039/d2cp00744d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Modeling intermolecular noncovalent interactions between large molecules remains a challenge for the electron structure theory community due to the high cost. Fragment-based methods usually fare well in reducing the cost...
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33
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McKinnon BI, Marlton SJP, Ucur B, Bieske EJ, Poad BLJ, Blanksby SJ, Trevitt AJ. Actinic Wavelength Action Spectroscopy of the IO - Reaction Intermediate. J Phys Chem Lett 2021; 12:11939-11944. [PMID: 34878800 DOI: 10.1021/acs.jpclett.1c03456] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Iodinate anions are important in the chemistry of the atmosphere where they are implicated in ozone depletion and particle formation. The atmospheric chemistry of iodine is a complex overlay of neutral-neutral, ion-neutral, and photochemical processes, where many of the reactions and intermediates remain poorly characterized. This study targets the visible spectroscopy and photostability of the gas-phase hypoiodite anion (IO-), the initial product of the I- + O3 reaction, by mass spectrometry equipped with resonance-enhanced photodissociation and total ion-loss action spectroscopies. It is shown that IO- undergoes photodissociation to I- + O (3P) over 637-459 nm (15700-21800 cm-1) because of excitation to the bound first singlet excited state. Electron photodetachment competes with photodissociation above the electron detachment threshold of IO- at 521 nm (19200 cm-1) with peaks corresponding to resonant autodetachment involving the singlet excited state and the ground state of neutral IO possibly mediated by a dipole-bound state.
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Affiliation(s)
- Benjamin I McKinnon
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Samuel J P Marlton
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Boris Ucur
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Evan J Bieske
- School of Chemistry, The University of Melbourne, Victoria 3010, Australia
| | - Berwyck L J Poad
- Central Analytical Research Facility, Queensland University of Technology, Brisbane 4001, Australia
- School of Chemistry and Physics, Queensland University of Technology, Brisbane 4001, Australia
| | - Stephen J Blanksby
- Central Analytical Research Facility, Queensland University of Technology, Brisbane 4001, Australia
- School of Chemistry and Physics, Queensland University of Technology, Brisbane 4001, Australia
| | - Adam J Trevitt
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
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34
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Bull JN, Anstöter CS, Stockett MH, Clarke CJ, Gibbard JA, Bieske EJ, Verlet JRR. Nonadiabatic Dynamics between Valence, Nonvalence, and Continuum Electronic States in a Heteropolycyclic Aromatic Hydrocarbon. J Phys Chem Lett 2021; 12:11811-11816. [PMID: 34870432 DOI: 10.1021/acs.jpclett.1c03532] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Internal conversion between valence-localized and dipole-bound states is thought to be a ubiquitous process in polar molecular anions, yet there is limited direct evidence. Here, photodetachment action spectroscopy and time-resolved photoelectron imaging with a heteropolycyclic aromatic hydrocarbon (hetero-PAH) anion, deprotonated 1-pyrenol, is used to demonstrate a subpicosecond (τ1 = 160 ± 20 fs) valence to dipole-bound state internal conversion following excitation of the origin transition of the first valence-localized excited state. The internal conversion dynamics are evident in the photoelectron spectra and in the photoelectron angular distributions (β2 values) as the electronic character of the excited state population changes from valence to nonvalence. The dipole-bound state subsequently decays through mode-specific vibrational autodetachment with a lifetime τ2 = 11 ± 2 ps. These internal conversion and autodetachment dynamics are likely common in molecular anions but difficult to fingerprint due to the transient existence of the dipole-bound state. Potential implications of the present excited state dynamics for interstellar hetero-PAH anion formation are discussed.
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Affiliation(s)
- James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Cate S Anstöter
- Department of Chemistry, Temple University, 1901 N 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Mark H Stockett
- Department of Physics, Stockholm University, Stockholm SE-106 91, Sweden
| | - Connor J Clarke
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Jemma A Gibbard
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Evan J Bieske
- School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
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35
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Kang DH, Kim J, Noh HR, Kim SK. Observation of the ponderomotive effect in non-valence bound states of polyatomic molecular anions. Nat Commun 2021; 12:7098. [PMID: 34876596 PMCID: PMC8651741 DOI: 10.1038/s41467-021-27468-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 11/22/2021] [Indexed: 12/03/2022] Open
Abstract
The ponderomotive force on molecular systems has rarely been observed hitherto, despite potentially being extremely useful for the manipulation of the molecular properties. Here, the ponderomotive effect in the non-valence bound states has been experimentally demonstrated, for the first time to the best of our knowledge, giving great promise for the manipulation of polyatomic molecules by the dynamic Stark effect. Entire quantum levels of the dipole-bound state (DBS) and quadrupole-bound state (QBS) of the phenoxide (or 4-bromophenoxide) and 4-cyanophenoxide anions, respectively, show clear-cut ponderomotive blue-shifts in the presence of the spatiotemporally overlapped non-resonant picosecond control laser pulse. The quasi-free electron in the QBS is found to be more vulnerable to the external oscillating electromagnetic field compared to that in the DBS, suggesting that the non-valence orbital of the former is more diffusive and thus more polarizable compared to that of the latter.
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Affiliation(s)
- Do Hyung Kang
- grid.37172.300000 0001 2292 0500Department of Chemistry, KAIST, Daejeon, 34141 Republic of Korea
| | - Jinwoo Kim
- grid.37172.300000 0001 2292 0500Department of Chemistry, KAIST, Daejeon, 34141 Republic of Korea
| | - Heung-Ryoul Noh
- grid.14005.300000 0001 0356 9399Department of Physics, Chonnam National University, Gwangju, 61186 Republic of Korea
| | - Sang Kyu Kim
- Department of Chemistry, KAIST, Daejeon, 34141, Republic of Korea.
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36
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Cao W, Zhang H, Yuan Q, Zhou X, Kass SR, Wang XB. Observation and Exploitation of Spin-Orbit Excited Dipole-Bound States in Ion-Molecule Clusters. J Phys Chem Lett 2021; 12:11022-11028. [PMID: 34739238 DOI: 10.1021/acs.jpclett.1c03309] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We report an observation of spin-orbit excited dipole-bound states (DBSs) in arginine-iodide complexes (Arg·I-) by using temperature-dependent, wavelength-resolved "iodide-tagging" negative ion photoelectron spectroscopy. The observed DBSs are bound to the spin-orbit excited I(2P1/2) level of the neutral Arg·I complex in zwitterionic conformations and identified based on the resonant enhancement due to spin-orbit electronic autodetachment from the I(2P1/2) DBS to the I(2P3/2) neutral ground state. The observed DBS binding energies are correlated to the dipole moments of neutral Arg·I isomers and tautomers. This work thus demonstrates a new and generic spectroscopic approach to identify ion-molecule cluster conformations based on their distinguishable dipole moments.
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Affiliation(s)
- Wenjin Cao
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Hanhui Zhang
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P.R. China
| | - Qinqin Yuan
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Xiaoguo Zhou
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P.R. China
| | - Steven R Kass
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Xue-Bin Wang
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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37
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Laws BA, Levey ZD, Schmidt TW, Gibson ST. Velocity Map Imaging Spectroscopy of the Dipole-Bound State of CH 2CN -: Implications for the Diffuse Interstellar Bands. J Am Chem Soc 2021; 143:18684-18692. [PMID: 34726415 DOI: 10.1021/jacs.1c08762] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Weakly bound anionic systems present a new domain for negative ion spectroscopy. Here we report on a multifaceted study of the CH2CN- dipole-bound state, employing high-resolution photoelectron spectroscopy from 130 different wavelengths, velocity-map imaging at threshold, and laser scanning photodetachment experiments. This uncovers a wide variety of different vibrational and rotational autodetaching resonances. By examination of both sides of the problem, absorption from the anion to the dipole-bound state and vibrational/rotational autodetachment to the neutral, a complete model of the dipole-bound chemistry is formed. Precise values for the electron affinity EA = 12468.9(1) cm-1, dipole binding energy DBE = 40.2(3) cm-1, and anion inversion splitting ω5 = 115.9(2) cm-1 are obtained. This model is then employed to study possible astronomical implications, revealing good agreement between the K = 1 ← 0 CH2CN- dipole transition and the λ8040 diffuse interstellar band.
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Affiliation(s)
- Benjamin A Laws
- School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia.,Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
| | - Zachariah D Levey
- School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia
| | - Timothy W Schmidt
- School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia
| | - Stephen T Gibson
- Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
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38
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Hsieh M, Huang G, Yu JK. Dipole‐bound states and substituent effects of Breslow intermediates in the enolate form. J CHIN CHEM SOC-TAIP 2021. [DOI: 10.1002/jccs.202100310] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Ming‐Hsiu Hsieh
- Institute of Bioinformatics and Systems Biology National Yang Ming Chiao Tung University Hsinchu Taiwan
| | - Gou‐Tao Huang
- Department of Biological Science and Technology National Yang Ming Chiao Tung University Hsinchu Taiwan
| | - Jen‐Shiang K. Yu
- Institute of Bioinformatics and Systems Biology, Department of Biological Science and Technology, and Institute of Molecular Medicine and Bioengineering National Yang Ming Chiao Tung University Hsinchu Taiwan
- Center for Intelligent Drug Systems and Smart Bio‐Devices National Yang Ming Chiao Tung University Hsinchu Taiwan
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39
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Dobulis MA, McGee CJ, Sommerfeld T, Jarrold CC. Autodetachment over Broad Photon Energy Ranges in the Anion Photoelectron Spectra of [O 2- M] - ( M = Glyoxal, Methylglyoxal, or Biacetyl) Complex Anions. J Phys Chem A 2021; 125:9128-9142. [PMID: 34623818 DOI: 10.1021/acs.jpca.1c07163] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Complexes of anion-neutral pairs are prevalent in chemical and physical processes in the interstellar medium, the atmosphere, and biological systems, among others. However, bimolecular anionic species that cannot be described as simple ion-molecule complexes due to their competitive electron affinities have received less attention. In this study, the [O2-M]- (M = glyoxal, methylglyoxal, or biacetyl) anion photoelectron spectra obtained with several different photon energies are reported and interpreted in the context of ab initio calculations. The spectra do not resemble the photoelectron spectra of M- or O2- "solvated" by a neutral partner. Rather, all spectra are dominated by near-threshold autodetachment from what are likely transient dipole bound states of the cis conformers of the complex anions. Very low Franck-Condon overlap between the neutral M·O2 van der Waals clusters and the partial covalently bound complex anions results in low-intensity, broad direct detachment observed in the spectra. The [O2-glyoxal]- spectra measured with 2.88 and 3.495 eV photon energies additionally exhibit features at ∼0.5 eV electron kinetic energy, which is more difficult to explain, though there are numerous quasibound states of the anion that may be involved. Overall, these features point to the inadequacy of describing the complex anions as simple ion-molecule complexes.
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Affiliation(s)
- Marissa A Dobulis
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Conor J McGee
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Thomas Sommerfeld
- Department of Chemistry and Physics, Southeast Louisiana University, SLU 10878, Hammond, Louisiana 70402, United States
| | - Caroline Chick Jarrold
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
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40
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Hart CA, Lyle J, Spellberg J, Krylov AI, Mabbs R. Role of the Electron-Dipole Interaction in Photodetachment Angular Distributions. J Phys Chem Lett 2021; 12:10086-10092. [PMID: 34624197 DOI: 10.1021/acs.jpclett.1c02882] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The importance of including long-range electron-molecule interactions in treatments of photodetachment and/or photoionization is demonstrated. A combined experimental and computational study of CN- detachment is presented in which near threshold anisotropy parameters (β) are measured via photoelectron imaging. Calculated β values, based on an EOM-IP-CCSD/aug-cc-pVTZ Dyson orbital, are obtained using free-particle and point dipole models. The results demonstrate the influence of the molecular dipole moment in the detachment process and provide an explanation of the recently reported near threshold behavior of the overall photodetachment cross section in CN- detachment.
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Affiliation(s)
- C Annie Hart
- Department of Chemistry, Washington University in St. Louis, 1 Brookings Drive, St. Louis, Missouri 63132, United States
| | - Justin Lyle
- Department of Chemistry, Washington University in St. Louis, 1 Brookings Drive, St. Louis, Missouri 63132, United States
| | - Joseph Spellberg
- Department of Chemistry, Washington University in St. Louis, 1 Brookings Drive, St. Louis, Missouri 63132, United States
| | - Anna I Krylov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Richard Mabbs
- Department of Chemistry, Washington University in St. Louis, 1 Brookings Drive, St. Louis, Missouri 63132, United States
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41
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Zhang YR, Yuan DF, Qian CH, Wang LS. Observation of a dipole-bound excited state in 4-ethynylphenoxide and comparison with the quadrupole-bound excited state in the isoelectronic 4-cyanophenoxide. J Chem Phys 2021; 155:124305. [PMID: 34598564 DOI: 10.1063/5.0065510] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Negative ions do not possess Rydberg states but can have Rydberg-like nonvalence excited states near the electron detachment threshold, including dipole-bound states (DBSs) and quadrupole-bound states (QBSs). While DBSs have been studied extensively, quadrupole-bound excited states have been more rarely observed. 4-cyanophenoxide (4CP-) was the first anion observed to possess a quadrupole-bound exited state 20 cm-1 below its detachment threshold. Here, we report the observation of a DBS in the isoelectronic 4-ethynylphenoxide anion (4EP-), providing a rare opportunity to compare the behaviors of a dipole-bound and a quadrupole-bound excited state in a pair of very similar anions. Photodetachment spectroscopy (PDS) of cryogenically cooled 4EP- reveals a DBS 76 cm-1 below its detachment threshold. Photoelectron spectroscopy (PES) at 266 nm shows that the electronic structure of 4EP- and 4CP- is nearly identical. The observed vibrational features in both the PDS and PES, as well as autodetachment from the nonvalence excited states, are also found to be similar for both anions. However, resonant two-photon detachment (R2PD) from the bound vibrational ground state is observed to be very different for the DBS in 4EP- and the QBS in 4CP-. The R2PD spectra reveal that decays take place from both the DBS and QBS to the respective anion ground electronic states within the 5 ns detachment laser pulse due to internal conversion followed by intramolecular vibrational redistribution and relaxation, but the decay mechanisms appear to be very different. In the R2PD spectrum of 4EP-, we observe strong threshold electron signals, which are due to detachment, by the second photon, of highly rotationally excited anions resulted from the decay of the DBS. On the other hand, in the R2PD spectrum of 4CP-, we observe well-resolved vibrational peaks due to the three lowest-frequency vibrational modes of 4CP-, which are populated from the decay of the QBS. The different behaviors of the R2PD spectra suggest unexpected differences between the relaxation mechanisms of the dipole-bound and quadrupole-bound excited states.
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Affiliation(s)
- Yue-Rou Zhang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | - Dao-Fu Yuan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | - Chen-Hui Qian
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
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42
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Gao Y, Zheng Y, Sanche L. Low-Energy Electron Damage to Condensed-Phase DNA and Its Constituents. Int J Mol Sci 2021; 22:7879. [PMID: 34360644 PMCID: PMC8345953 DOI: 10.3390/ijms22157879] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/30/2021] [Accepted: 06/30/2021] [Indexed: 11/18/2022] Open
Abstract
The complex physical and chemical reactions between the large number of low-energy (0-30 eV) electrons (LEEs) released by high energy radiation interacting with genetic material can lead to the formation of various DNA lesions such as crosslinks, single strand breaks, base modifications, and cleavage, as well as double strand breaks and other cluster damages. When crosslinks and cluster damages cannot be repaired by the cell, they can cause genetic loss of information, mutations, apoptosis, and promote genomic instability. Through the efforts of many research groups in the past two decades, the study of the interaction between LEEs and DNA under different experimental conditions has unveiled some of the main mechanisms responsible for these damages. In the present review, we focus on experimental investigations in the condensed phase that range from fundamental DNA constituents to oligonucleotides, synthetic duplex DNA, and bacterial (i.e., plasmid) DNA. These targets were irradiated either with LEEs from a monoenergetic-electron or photoelectron source, as sub-monolayer, monolayer, or multilayer films and within clusters or water solutions. Each type of experiment is briefly described, and the observed DNA damages are reported, along with the proposed mechanisms. Defining the role of LEEs within the sequence of events leading to radiobiological lesions contributes to our understanding of the action of radiation on living organisms, over a wide range of initial radiation energies. Applications of the interaction of LEEs with DNA to radiotherapy are briefly summarized.
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Affiliation(s)
- Yingxia Gao
- State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou 350116, China;
| | - Yi Zheng
- State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou 350116, China;
| | - Léon Sanche
- Département de Médecine Nucléaire et Radiobiologie et Centre de Recherche Clinique, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada;
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43
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Kang DH, Kim J, Kim SK. Recapture of the Nonvalence Excess Electron into the Excited Valence Orbital Leads to the Chemical Bond Cleavage in the Anion. J Phys Chem Lett 2021; 12:6383-6388. [PMID: 34232669 DOI: 10.1021/acs.jpclett.1c01789] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The excess electron in the dipole-bound state (DBS) of the anion is found to be recaptured into the excited valence orbital localized at the positive end of the dipole, leading to the chemical bond cleavage of the anion. In the DBS of the 4-iodophenoxide anion, the extremely loosely bound electron (binding energy of 53 cm-1) is recaptured into the πσ* valence orbital, which is repulsive along the C-I bond extension coordinate, leading to the iodide (I-) and phenoxyl diradical (·C6H4O·) channel at the asymptotic limit. This is the first real-time observation of the state-specific relaxation (other than autodetachment) dynamics of the DBS and subsequent chemical reaction. The lifetime of the 4-iodophenoxide DBS at its zero-point energy (ZPE), which is measured for the cryogenically cooled trapped anion using the picosecond laser pump-probe scheme, has been estimated to be ∼9.5 ± 0.3 ps. Quantum mechanical calculations support the efficient transition from the DBS (below the detachment threshold) to the low-lying πσ* valence orbital of the first excited state of the anion. Similar experiments on 4-chlorophenoxide and 4-bromophenoxide anions indicate that the electron recaptures into excited valence orbitals hardly occur in the DBS of those anions, giving the long lifetimes (≫ns) at ZPE, suggesting that the internal conversion to S0 may be the major relaxation pathway for those anions.
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Affiliation(s)
- Do Hyung Kang
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Jinwoo Kim
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Sang Kyu Kim
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
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44
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Lu Y, Tang R, Ning C. Observation of an Excited Dipole-Bound State in a Diatomic Anion. J Phys Chem Lett 2021; 12:5897-5902. [PMID: 34151577 DOI: 10.1021/acs.jpclett.1c01726] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We report the observation of σ-type and π-type excited dipole-bound states (DBSs) in cryogenically cooled potassium iodide (KI) anions for the first time. Two DBSs were observed 39.7(10) meV and 5.0(12) meV below the photodetachment threshold via the resonant two-photon detachment. The different photoelectron angular distributions and binding energies suggest that the two DBSs are of different types. The existence of one σ-type and one π-type DBS in the KI anion was also supported by the high-level ab initio theoretical calculations. The excellent agreement between experimental and theoretical results confirms the prediction that a dipolar molecule with a large enough dipole moment can have an excited DBS.
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Affiliation(s)
- Yuzhu Lu
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing 10084, China
| | - Rulin Tang
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing 10084, China
| | - Chuangang Ning
- Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing 10084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
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45
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Yuan DF, Zhang YR, Qian CH, Liu Y, Wang LS. Probing the Dipole-Bound State in the 9-Phenanthrolate Anion by Photodetachment Spectroscopy, Resonant Two-Photon Photoelectron Imaging, and Resonant Photoelectron Spectroscopy. J Phys Chem A 2021; 125:2967-2976. [DOI: 10.1021/acs.jpca.1c01563] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Dao-Fu Yuan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Yue-Rou Zhang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Chen-Hui Qian
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Yuan Liu
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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46
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Qian CH, Zhang YR, Yuan DF, Wang LS. Photodetachment spectroscopy and resonant photoelectron imaging of cryogenically cooled 1-pyrenolate. J Chem Phys 2021; 154:094308. [PMID: 33685163 DOI: 10.1063/5.0043932] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We report an investigation of the 1-pyrenolate anion (PyO-) and the 1-pyrenoxy radical (PyO) using photodetachment spectroscopy and resonant photoelectron imaging of cryogenically cooled anions. The electron affinity of PyO is measured to be 2.4772(4) eV (19 980 ± 3 cm-1) from high-resolution photoelectron spectroscopy. Photodetachment spectroscopy reveals a dipole-bound state (DBS) for PyO- 280 cm-1 below the detachment threshold as well as a broad and intense valence excited state (shape resonance) 1077 cm-1 above the detachment threshold. The shape resonance with an excitation energy of 21 055 cm-1 is due to excitation of an electron from the highest occupied molecular orbital of PyO- to its lowest unoccupied molecular orbital in the continuum. Twenty-nine vibrational levels of the DBS are observed, including 27 above-threshold vibrational levels (vibrational Feshbach resonances). Twenty-seven resonant photoelectron spectra are obtained by tuning the detachment laser to the vibrational Feshbach resonances, resulting in highly non-Franck-Condon photoelectron spectra and rich vibrational information. In total, the frequencies of 21 vibrational modes are obtained for the PyO radical by the combination of the photodetachment and resonant photoelectron spectroscopy, including 13 out-of-plane bending modes.
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Affiliation(s)
- Chen-Hui Qian
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | - Yue-Rou Zhang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | - Dao-Fu Yuan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
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47
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Kang DH, Kim J, Cheng M, Kim SK. Mode-Specific Autodetachment Dynamics of an Excited Non-valence Quadrupole-Bound State. J Phys Chem Lett 2021; 12:1947-1954. [PMID: 33591762 DOI: 10.1021/acs.jpclett.1c00169] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The autodetachment dynamics of vibrational Feshbach resonances of the quadrupole-bound state (QBS) for the first time has been investigated in real time for the first excited state of the 4-cyanophenoxide (4-CP) anion. Individual vibrational resonances of the cryogenically cooled 4-CP QBS have been unambiguously identified, and their autodetachment rates state-specifically measured using the picosecond time-resolved pump-probe technique employing the photoelectron velocity-map imaging method. The autodetachment lifetime (τ) is found to be strongly dependent on mode, giving τ values of ∼56, ∼27, and ≤2.8 ps for the 12'1 (Evib = 406 cm-1), 12'2 (Evib = 806 cm-1), and 21'1 (Evib = 220 cm-1) modes, respectively. The striking mode-specific behavior of the QBS lifetime has been invoked by the physical model in which the loosely bound electron falls off by the dynamic wobbling of the three-dimensional quadrupole moment ellipsoid associated with the corresponding vibrational motion in the autodetachment process.
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Affiliation(s)
- Do Hyung Kang
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Jinwoo Kim
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Min Cheng
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Sang Kyu Kim
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
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48
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Voora VK. Molecular Electron Affinities Using the Generalized Kohn-Sham Semicanonical Projected Random Phase Approximation. J Phys Chem Lett 2021; 12:433-439. [PMID: 33356311 DOI: 10.1021/acs.jpclett.0c03362] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The suitability of one-particle energies from the generalized Kohn-Sham semicanonical projected random phase approximation (GKS-spRPA) method for electron affinities of molecules is investigated. It is shown that the GKS-spPRA effective potential includes exact exchange and polarizability-dependent correlation terms that are necessary for the correct description of anionic systems. An O(N4) implementation that enables fast computation of electron affinities is presented. For model systems, I show that the GKS-spRPA approach is applicable for valence and nonvalence type anions with a maximum error of 0.13 eV for valence anionic states and 0.03 eV for nonvalence anionic states compared to equation of motion coupled cluster methods. For a series of perhalobenzene molecules, C6X6 (X= F, Cl, Br, and I), GKS-spRPA predicts that the ground-state character changes from a nonvalence-σ* type in C6F6- to valence-π* in C6Cl6- and valence-σ* in C6Br6- and C6I6-. Experimental implications of these findings are discussed.
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Affiliation(s)
- Vamsee K Voora
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
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49
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Liu Y, Zhu GZ, Yuan DF, Qian CH, Zhang YR, Rubenstein BM, Wang LS. Observation of a Symmetry-Forbidden Excited Quadrupole-Bound State. J Am Chem Soc 2020; 142:20240-20246. [PMID: 33185446 DOI: 10.1021/jacs.0c10552] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We report the observation of a symmetry-forbidden excited quadrupole-bound state (QBS) in the tetracyanobenzene anion (TCNB-) using both photoelectron and photodetachment spectroscopies of cryogenically-cooled anions. The electron affinity of TCNB is accurately measured as 2.4695 eV. Photodetachment spectroscopy of TCNB- reveals selected symmetry-allowed vibronic transitions to the QBS, but the ground vibrational state was not observed because the transition from the ground state of TCNB- (Au symmetry) to the QBS (Ag symmetry) is triply forbidden by the electric and magnetic dipoles and the electric quadrupole. The binding energy of the QBS is found to be 0.2206 eV, which is unusually large due to strong correlation and polarization effects. A centrifugal barrier is observed for near-threshold autodetachment, as well as relaxations from the QBS vibronic levels to the ground and a valence excited state of TCNB-. The current study shows a rare example where symmetry selection rules, rather than the Franck-Condon principle, govern vibronic transitions to a nonvalence state in an anion.
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Affiliation(s)
- Yuan Liu
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Guo-Zhu Zhu
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Dao-Fu Yuan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Chen-Hui Qian
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Yue-Rou Zhang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Brenda M Rubenstein
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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50
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Anstöter CS, Matsika S. Understanding the Interplay between the Nonvalence and Valence States of the Uracil Anion upon Monohydration. J Phys Chem A 2020; 124:9237-9243. [DOI: 10.1021/acs.jpca.0c07407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Cate S. Anstöter
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Spiridoula Matsika
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
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