1
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Mulvey D, Jordan KD. Demonstrating the Connection between the Nonvalence Correlation-Bound Anions of Polyaromatic Hydrocarbons and the Image Potential States of Graphene Using a One-Electron Model Hamiltonian. J Phys Chem Lett 2024; 15:6299-6305. [PMID: 38856081 PMCID: PMC11194819 DOI: 10.1021/acs.jpclett.4c01308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2024] [Revised: 05/29/2024] [Accepted: 06/04/2024] [Indexed: 06/11/2024]
Abstract
The ground and excited state nonvalence correlation-bound (NVCB) anion states of the C 6 n 2 H 6 n hexagonal polycylic aromatic hydrocarbons and of hexagonal C 6 n 2 graphene nanoflakes are characterized using a one-electron model Hamiltonian which incorporates atomic electrostatic moments up to the quadrupole, coupled inducible charges and dipoles, and atom-centered Gaussians to describe the short-range repulsive interactions. Extrapolation of the calculated electron binding energies of the lowest energy symmetric and antisymmetric (with respect to the molecular plane) NVCB anions of both the polycylic aromatic hydrocarbons and the carbon nanoflakes to the n → ∞ limit yields binding energies that are in good agreement with those of the most stable symmetric and antisymmetric image potential states of freestanding graphene as determined from two-photon photoemission spectroscopy (2PPE) experiments.
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Affiliation(s)
- Devin
M. Mulvey
- Department of Chemistry, University
of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
| | - Kenneth D. Jordan
- Department of Chemistry, University
of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
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2
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Hart CA, Schlimgen AW, Dao DB, Head-Marsden K, Mabbs R. The overlooked role of excited anion states in NiO2- photodetachment. J Chem Phys 2024; 160:044304. [PMID: 38258918 DOI: 10.1063/5.0188066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Accepted: 01/01/2024] [Indexed: 01/24/2024] Open
Abstract
Photodetachment spectra of anionic species provide significant insights into the energies and nature of ground and excited states of both the anion and resultant neutral molecules. Direct detachment of the excess electron to the continuum may occur via formally allowed or forbidden transitions (perhaps as the result of intensity borrowing through vibronic coupling). However, alternate indirect pathways are also possible and often overlooked. Here, we report a two-dimensional photoelectron spectral study, combined with correlated electronic structure calculations, to elucidate the nature of photodetachment from NiO2-. The spectra are comprised of allowed and forbidden transitions, in excellent agreement with previously reported slow electron velocity mapped imaging spectra of the same system, which were interpreted in terms of direct detachment. In the current work, the contributions of indirect processes are revealed. Measured oscillations in the branching ratios of the spectral channels clearly indicate non-direct detachment processes, and the electronic structure calculations suggest that excited states of the appropriate symmetry and degeneracy lie slightly above the neutral ground state. Taken together, the results suggest that the origin of the observed forbidden transitions is the result of anion excited states mediating the electron detachment process.
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Affiliation(s)
- C Annie Hart
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130-4862, USA
| | - Anthony W Schlimgen
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130-4862, USA
| | - Diep Bich Dao
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130-4862, USA
| | - Kade Head-Marsden
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130-4862, USA
| | - Richard Mabbs
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130-4862, USA
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3
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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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4
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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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5
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Ranković M, Nag P, Anstöter CS, Mensa-Bonsu G, Kumar T P R, Verlet JRR, Fedor J. Resonances in nitrobenzene probed by the electron attachment to neutral and by the photodetachment from anion. J Chem Phys 2022; 157:064302. [PMID: 35963718 DOI: 10.1063/5.0101358] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We probe resonances (transient anions) in nitrobenzene with the focus on the electron emission from these. Experimentally, we populate resonances in two ways: either by the impact of free electrons on the neutral molecule or by the photoexcitation of the bound molecular anion. These two excitation means lead to transient anions in different initial geometries. In both cases, the anions decay by electron emission and we record the electron spectra. Several types of emission are recognized, differing by the way in which the resulting molecule is vibrationally excited. In the excitation of specific vibrational modes, distinctly different modes are visible in electron collision and photodetachment experiments. The unspecific vibrational excitation, which leads to the emission of thermal electrons following the internal vibrational redistribution, shows similar features in both experiments. A model for the thermal emission based on a detailed balance principle agrees with the experimental findings very well. Finally, a similar behavior in the two experiments is also observed for a third type of electron emission, the vibrational autodetachment, which yields electrons with constant final energies over a broad range of excitation energies. The entrance channels for the vibrational autodetachment are examined in detail, and they point to a new mechanism involving a reverse valence to non-valence internal conversion.
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Affiliation(s)
- Miloš Ranković
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - Pamir Nag
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - Cate S Anstöter
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Golda Mensa-Bonsu
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Ragesh Kumar T P
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Juraj Fedor
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic
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6
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Anstöter CS, Verlet JRR. A Hückel Model for the Excited-State Dynamics of a Protein Chromophore Developed Using Photoelectron Imaging. Acc Chem Res 2022; 55:1205-1213. [PMID: 35172580 PMCID: PMC9084545 DOI: 10.1021/acs.accounts.1c00780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Chemistry can be described as the movement of nuclei within molecules and the concomitant instantaneous change in electronic structure. This idea underpins the central chemical concepts of potential energy surfaces and reaction coordinates. To experimentally capture such chemical change therefore requires methods that can probe both the nuclear and electronic structure simultaneously and on the time scale of atomic motion. In this Account, we show how time-resolved photoelectron imaging can do exactly this and how it can be used to build a detailed and intuitive understanding of the electronic structure and excited-state dynamics of chromophores. The chromophore of the photoactive yellow protein (PYP) is used as a case study. This chromophore contains a para-substituted phenolate anion, where the substituent, R, can be viewed as an acrolein derivative. It is shown that the measured photoelectron angular distribution can be directly related to the electronic structure of the para-substituted phenolate anion. By incrementally considering differing R groups, it is also shown that these photoelectron angular distributions are exquisitely sensitive to the conformational flexibility of R and that when R contains a π-system the excited states of the chromophore can be viewed as a linear combination of the π* molecular orbitals on the phenolate (πPh*) and the R substituent (πR*). Such Hückel treatment shows that the S1 state of the PYP chromophore has predominantly πR* character and that it is essentially the same as the chromophore of the green fluorescent protein (GFP). The S1 excited-state dynamics of the PYP chromophore probed by time-resolved photoelectron imaging clearly reveals both structural (nuclear) dynamics through the energy spectrum and electronic dynamics through the photoelectron angular distributions. Both motions can be accurately assigned using quantum chemical calculations, and these are consistent with the intuitive Hückel treatment presented. The photoactive protein chromophores considered here are examples of where a chemists' intuitive Hückel view for ground-state chemistry appears to be transferable to the prediction of photochemical excited-state reactivity. While elegant and insightful, such models have limitations, including nonadiabatic dynamics, which is present in a related PYP chromophore, where a fraction of the S1 state population forms a nonvalence (dipole-bound) state of the anion.
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Affiliation(s)
- Cate S. Anstöter
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Jan R. R. Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
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7
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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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8
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Chou SL, Lin SY, Lin MY, Wu YJ. IR absorption spectra of hexafluorobenzene anions and pentafluorophenyl radicals in solid argon. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 252:119524. [PMID: 33582441 DOI: 10.1016/j.saa.2021.119524] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 01/11/2021] [Accepted: 01/21/2021] [Indexed: 06/12/2023]
Abstract
Hexafluorobenzene anions (HFB-) and pentafluorophenyl radicals (PFP) were generated by the electron bombardment of a HFB/Ar sample during matrix deposition. Further irradiation of the matrix sample at 365 nm detached the electron from HFB- and produced its neutral counterpart HFB in solid Ar. Secondary photolysis of the matrix sample at 160 nm destroyed HFB and generated HFB- and PFP. In a separate experiment, the photolysis of the HFB/Ar matrix at 160 nm produced PFP, Dewar-C6F6, and various neutral fluorocarbon species, but without the production of HFB-. The infrared (IR) lines of HFB- and PFP were assigned on the basis of the observed photochemical behaviors, as well as by comparing the predictions of the vibrational wavenumbers with the corresponding IR intensities and the relative stabilities of the related species predicted via the B3LYP/aug-cc-pVTZ theory.
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Affiliation(s)
- Sheng-Lung Chou
- National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan
| | - Shu-Yu Lin
- National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan
| | - Meng-Yeh Lin
- National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan
| | - Yu-Jong Wu
- National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan; Department of Applied Chemistry, National Chiao Tung University, 1001, Ta-Hsueh Road, Hsinchu 30010, Taiwan.
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9
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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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10
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Upadhyay S, Dumi A, Shee J, Jordan KD. The role of high-order electron correlation effects in a model system for non-valence correlation-bound anions. J Chem Phys 2020; 153:224118. [DOI: 10.1063/5.0030942] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- Shiv Upadhyay
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Amanda Dumi
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - James Shee
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, USA
| | - Kenneth D. Jordan
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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11
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Verlet JRR, Anstöter CS, Bull JN, Rogers JP. Role of Nonvalence States in the Ultrafast Dynamics of Isolated Anions. J Phys Chem A 2020; 124:3507-3519. [PMID: 32233436 PMCID: PMC7212518 DOI: 10.1021/acs.jpca.0c01260] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Nonvalence states
of neutral molecules (Rydberg states) play important
roles in nonadiabatic dynamics of excited states. In anions, such
nonadiabatic transitions between nonvalence and valence states have
been much less explored even though they are believed to play important
roles in electron capture and excited state dynamics of anions. The
aim of this Feature Article is to provide an overview of recent experimental
observations, based on time-resolved photoelectron imaging, of valence
to nonvalence and nonvalence to valence transitions in anions and
to demonstrate that such dynamics may be commonplace in the excited
state dynamics of molecular anions and cluster anions.
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Affiliation(s)
- Jan R R Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Cate S Anstöter
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Joshua P Rogers
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
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12
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Castellani ME, Anstöter CS, Verlet JRR. On the stability of a dipole-bound state in the presence of a molecule. Phys Chem Chem Phys 2019; 21:24286-24290. [PMID: 31663558 DOI: 10.1039/c9cp04942h] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dipole-bound states (DBSs) are diffuse non-valence molecular orbitals of anions where the electron is bound by the permanent dipole moment of the neutral core. Here, an experimental study of the stability of such orbitals under the influence of a perturbing molecular alkyl chain is presented. Photodetachment action and photoelectron imaging spectroscopy of five para-substituted phenolate anions with progressively longer alkyl chains show that the DBS survives in all cases, suggesting that the perturbation of the orbital is not critical to the existence of the DBS.
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13
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Mensa-Bonsu G, Tozer DJ, Verlet JRR. Photoelectron spectroscopic study of I -·ICF 3: a frontside attack S N2 pre-reaction complex. Phys Chem Chem Phys 2019; 21:13977-13985. [PMID: 30534728 DOI: 10.1039/c8cp06593d] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photodetachment and 2D photoelectron spectra of the mass-selected I-·CF3I complex are presented together with electronic structure calculations. Calculations show that the I- is located at the iodine side of CF3I. Vertical and adiabatic detachment energies were measured at 4.03 and approximately 3.8 eV, respectively. The photoelectron spectra and molecular orbitals show a significant covalent bonding character in the cluster. The presence of electronic excited states is observed. Below threshold, iodide is generated which can be assigned to the photoexcitation of degenerate charge-transfer bands from the off-axis p-orbitals localised on iodide. Near the onset of two spin-orbit thresholds, bright excited states are seen in the experiment and calculations. Excitation of these leads to the formation of slow electrons. The spectroscopy of I-·CF3I is compared to the well-studied I-·CH3I cluster, a pre-reaction complex in the text-book I- + CH3I SN2 reaction. Despite the reversed stereodynamics (i.e. inversion of the CX3 between X = H and F) of the SN2 reaction, striking similarities are seen. Both complexes possess charge transfer excited states near their respective vertical detachment energies and exhibit vibrational structure in their photoelectron spectra. The strong binding is consistent with observations in crossed molecular beam studies and molecular dynamics simulations that suggest that iodine as a leaving group in an SN2 reaction affects the reaction dynamics.
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14
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Anstöter CS, Rogers JP, Verlet JRR. Spectroscopic Determination of an Anion−π Bond Strength. J Am Chem Soc 2019; 141:6132-6135. [DOI: 10.1021/jacs.9b01345] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Cate S. Anstöter
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Joshua P. Rogers
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Jan R. R. Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
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15
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Tyson AL, Verlet JRR. On the Mechanism of Phenolate Photo-Oxidation in Aqueous Solution. J Phys Chem B 2019; 123:2373-2379. [PMID: 30768899 DOI: 10.1021/acs.jpcb.8b11766] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The photo-oxidation dynamics following ultraviolet (257 nm) excitation of the phenolate anion in aqueous solution is studied using broadband (550-950 nm) transient absorption spectroscopy. A clear signature from electron ejection is observed on a sub-picosecond timescale, followed by cooling dynamics and the decay of the signal to a constant offset that is assigned to the hydrated electron. The dynamics are compared to the charge-transfer-to-solvent dynamics from iodide at the same excitation wavelength and are shown to be very similar to these. This is in stark contrast to a previous study on the phenolate anion excited at 266 nm, in which electron emission was observed over longer timescales. We account for the differences using a simple Marcus picture for electron emission in which the electron tunneling rate depends sensitively on the initial excitation energy. After electron emission, a contact pair is formed which undergoes geminate recombination and dissociation to form the free hydrated electron at rates that are slightly faster than those for the iodide system. Our results show that, although the underlying chemical physics of electron emission differs between iodide and phenolate, the observed dynamics can appear very similar.
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Affiliation(s)
| | - Jan R R Verlet
- Department of Chemistry , Durham University , Durham DH1 3LE , U.K
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16
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Kairalapova A, Jordan KD, Maienshein DN, Fair MC, Falcetta MF. Prediction of a Nonvalence Temporary Anion Shape Resonance for a Model (H2O)4 System. J Phys Chem A 2019; 123:2719-2726. [DOI: 10.1021/acs.jpca.8b11881] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Arailym Kairalapova
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Kenneth D. Jordan
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Daniel N. Maienshein
- Department of Chemistry, Grove City College, Grove City, Pennsylvania 16127, United States
| | - Mark C. Fair
- Department of Chemistry, Grove City College, Grove City, Pennsylvania 16127, United States
| | - Michael F. Falcetta
- Department of Chemistry, Grove City College, Grove City, Pennsylvania 16127, United States
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17
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Rogers JP, Anstöter CS, Bull JN, Curchod BFE, Verlet JRR. Photoelectron Spectroscopy of the Hexafluorobenzene Cluster Anions: (C 6F 6) n- ( n = 1-5) and I -(C 6F 6). J Phys Chem A 2019; 123:1602-1612. [PMID: 30694676 DOI: 10.1021/acs.jpca.8b11627] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Frequency-resolved (2D) photoelectron (PE) spectra of the anionic clusters (C6F6) n-, for n = 1-5, and time-resolved PE spectra of I-C6F6 are presented using a newly built instrument and supported by electronic structure calculations. From the 2D PE spectra, the vertical detachment energy (VDE) of C6F6- was measured to be 1.60 ± 0.01 eV, and the adiabatic detachment energy (ADE) was ≤0.70 eV. The PE spectra also contain fingerprints of resonance dynamics over certain photon energy ranges, in agreement with the calculations. An action spectrum over the lowest resonance is also presented. The 2D spectra of (C6F6) n- show that the cluster can be described as C6F6-(C6F6) n-1. The VDE increases linearly (200 ± 20 meV n-1) due to the stabilizing influence on the anion of the solvating C6F6 molecules. For I-C6F6, action spectra of the absorption just below both detachment channels are presented. Time-resolved PE spectra of I-C6F6 excited at 3.10 eV and probed at 1.55 eV reveal a short-lived nonvalence state of C6F6- that coherently evolves into the valence ground state of the anion and induces vibrational motion along a specific buckling coordinate. Electronic structure calculations along the displacement of this mode show that at the extreme buckling angle the probe can access an excited state of the anion that is bound at that geometry but adiabatically unbound. Hence, slow electrons are emitted and show dynamics that predominantly probe the outer-turning point of the motion. A PE spectrum taken at t = 0 contains a vibrational structure assigned to a specific Raman- or IR-active mode of C6F6.
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Affiliation(s)
- Joshua P Rogers
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
| | - Cate S Anstöter
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
| | - James N Bull
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
| | - Basile F E Curchod
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
| | - Jan R R Verlet
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
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18
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Choi TH, Jordan KD. Model potential study of non-valence correlation-bound anions of (C60)n clusters: the role of electric field-induced charge transfer. Faraday Discuss 2019; 217:547-560. [DOI: 10.1039/c8fd00199e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Orbitals associated with the non-valence correlation-bound anions of the C60 dimer and linear trimer from calculations allowing charge transfer.
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Affiliation(s)
- Tae Hoon Choi
- Department of Chemistry
- University of Pittsburgh
- Pittsburgh
- USA
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19
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Anstöter CS, Gartmann TE, Stanley LH, Bochenkova AV, Verlet JRR. Electronic structure of the para-dinitrobenzene radical anion: a combined 2D photoelectron imaging and computational study. Phys Chem Chem Phys 2018; 20:24019-24026. [DOI: 10.1039/c8cp04877k] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
2D photoelectron spectroscopy combined with high-level ab initio calculations provides insights into the dissociative electron attachment of para-dinitrobenzene.
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Affiliation(s)
- Cate S. Anstöter
- Department of Chemistry
- Durham University
- Durham DH1 3LE
- UK
- Department of Chemistry
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