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Jerosimić S, Milovanović M, Mitić M, Wester R, Gianturco FA. Investigating Possible Dipole-Bound States of Cyanopolyynes: the Case for the C 5 N - Anion Detected in Interstellar Space. Chemphyschem 2023; 24:e202300248. [PMID: 37585236 PMCID: PMC10962575 DOI: 10.1002/cphc.202300248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 08/11/2023] [Accepted: 08/11/2023] [Indexed: 08/17/2023]
Abstract
We present results of quantum structure calculations aimed at demonstrating the possible existence of dipole-bound states (DBS) for the anionC 5 N - ${{\rm{C}}_5 {\rm{N}}^ - }$ , a species already detected in the Interstellar medium (ISM). The positive demonstration of DBS existence using ab initio studies is an important step toward elucidating possible pathways for the formation of the more tightly bound valence bound states (VBS) in environments where free electrons from starlight ionization processes are known to be available to interact with the radical partner of the title molecule. Our current calculations show that such excited DBS states can exist inC 5 N - ${{\rm{C}}_5 {\rm{N}}^ - }$ , in agreement with what we had previously found for the smallercyanopolyyne in the series: theC 3 N - ${{\rm{C}}_3 {\rm{N}}^ - }$ anion. This system has a very weakly bound anion with binding energies of about 3 and 9 cm-1 for the1 Σ + ${^1 \Sigma ^ + }$ and3 Σ + ${^3 \Sigma ^ + }$ DBS, respectively.
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Affiliation(s)
- Stanka Jerosimić
- University of Belgrade -Faculty of Physical ChemistryStu-dentski trg 12–1611158BelgradeSerbia
| | - Milan Milovanović
- University of Belgrade -Faculty of Physical ChemistryStu-dentski trg 12–1611158BelgradeSerbia
| | - Marko Mitić
- University of Belgrade -Faculty of Physical ChemistryStu-dentski trg 12–1611158BelgradeSerbia
| | - Roland Wester
- Institut für Ionenphysik und Angewandte PhysikUniversitaet InnsbruckTechnikerstr. 25A-6020InnsbruckAustria
| | - Francesco A. Gianturco
- Institut für Ionenphysik und Angewandte PhysikUniversitaet InnsbruckTechnikerstr. 25A-6020InnsbruckAustria
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Nötzold M, Wild R, Lochmann C, Rahim T, Melath SP, Dulitz K, Mant B, Franz J, Gianturco FA, Wester R. Vibrational Quenching of Optically Pumped Carbon Dimer Anions. PHYSICAL REVIEW LETTERS 2023; 131:183002. [PMID: 37977634 DOI: 10.1103/physrevlett.131.183002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 08/08/2023] [Accepted: 09/25/2023] [Indexed: 11/19/2023]
Abstract
Careful control of quantum states is a gateway to research in many areas of science such as quantum information, quantum-controlled chemistry, and astrophysical processes. Precise optical control of molecular ions remains a challenge due to the scarcity of suitable level schemes, and direct laser cooling has not yet been achieved for either positive or negative molecular ions. Using a cryogenic wire trap, we show how the internal quantum states of C_{2}^{-} anions can be manipulated using optical pumping and inelastic quenching collisions with H_{2} gas. We obtained optical pumping efficiencies of about 96% into the first vibrational level of C_{2}^{-} and determined the absolute inelastic rate coefficient from v=1 to 0 to be k_{q}=(3.2±0.2_{stat}±1.3_{sys})×10^{-13} cm^{3}/s at 20(3) K, over 3 orders of magnitude smaller than the capture limit. Reduced-dimensional quantum scattering calculations yield a small rate coefficient as well, but significantly larger than the experimental value. Using optical pumping and inelastic collisions, we also realized fluorescence imaging of negative molecular ions. Our work demonstrates high control of a cold ensemble of C_{2}^{-}, providing a solid foundation for future work on laser cooling of molecular ions.
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Affiliation(s)
- Markus Nötzold
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Robert Wild
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Christine Lochmann
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Tanja Rahim
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Sruthi Purushu Melath
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Katrin Dulitz
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Barry Mant
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Jan Franz
- Faculty of Applied Physics and Mathematics and Advanced Materials Center, Gdańsk University of Technology, 80-233 Gdańsk, Poland
| | - Francesco A Gianturco
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Roland Wester
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
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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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Dahlmann F, Dinu DF, Jusko P, Lochmann C, Gstir T, Marimuthu AN, Liedl KR, Brünken S, Wester R. Vibrational Predissociation Spectra of C 2 N - and C 3 N - : Bending and Stretching Vibrations. Chemphyschem 2023; 24:e202300262. [PMID: 37199236 PMCID: PMC10962567 DOI: 10.1002/cphc.202300262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 05/14/2023] [Accepted: 05/15/2023] [Indexed: 05/19/2023]
Abstract
We present infrared predissociation spectra of C2 N- (H2 ) and C 3 N- (H2 ) in the 300-1850 cm-1 range. Measurements were performed using the FELion cryogenic ion trap end user station at the Free Electron Lasers for Infrared eXperiments (FELIX) laboratory. For C2 N- (H2 ), we detected the CCN bending and CC-N stretching vibrations. For the C3 N- (H2 ) system, we detected the CCN bending, the CC-CN stretching, and multiple overtones and/or combination bands. The assignment and interpretation of the presented experimental spectra is validated by calculations of anharmonic spectra within the vibrational configuration interaction (VCI) approach, based on potential energy surfaces calculated at explicitly correlated coupled cluster theory (CCSD(T)-F12/cc-pVTZ-F12). The H2 tag acts as an innocent spectator, not significantly affecting the C2,3 N- bending and stretching mode positions. The recorded infrared predissociation spectra can thus be used as a proxy for the vibrational spectra of the bare anions.
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Affiliation(s)
- Franziska Dahlmann
- Institut für Ionenphysik und Angewandte PhysikUniversität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Dennis F. Dinu
- Department of GeneralInorganic and Theoretical ChemistryUniversität InnsbruckInnrain 80/826020InnsbruckAustria
| | - Pavol Jusko
- Max Planck Institute for Extraterrestrial PhysicsGießenbachstraße 185748GarchingGermany
| | - Christine Lochmann
- Institut für Ionenphysik und Angewandte PhysikUniversität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Thomas Gstir
- Institut für Ionenphysik und Angewandte PhysikUniversität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Aravindh N. Marimuthu
- Radboud UniversityInstitute for Molecules and MaterialsFELIX LaboratoryToernooiveld 76525EDNijmegen, theNetherlands
| | - Klaus R. Liedl
- Department of GeneralInorganic and Theoretical ChemistryUniversität InnsbruckInnrain 80/826020InnsbruckAustria
| | - Sandra Brünken
- Radboud UniversityInstitute for Molecules and MaterialsFELIX LaboratoryToernooiveld 76525EDNijmegen, theNetherlands
| | - Roland Wester
- Institut für Ionenphysik und Angewandte PhysikUniversität InnsbruckTechnikerstraße 256020InnsbruckAustria
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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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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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