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Egorov O, Rey M, Nikitin AV, Viglaska D. New Theoretical Infrared Line List for the Methyl Radical with Accurate Vibrational Band Origins from High-Level Ab Initio Calculations. J Phys Chem A 2022; 126:6429-6442. [PMID: 36073030 DOI: 10.1021/acs.jpca.2c04822] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the present work, high-level ab initio calculations were carried out for the ground electronic state of the methyl radical (CH3). Dunning's augmented correlation-consistent orbital basis sets were employed up to the quintuple-ζ valence quality with the core-valence electron correlation [aug-cc-pCV5Z] combined with the single- and double-excitation unrestricted coupled-cluster approach with a perturbative treatment of triple excitations [RHF-UCCSD(T)]. The explicitly correlated version of the coupled-cluster approach [RHF-UCCSD(T)-F12x{x = a, b}] was additionally applied with the core-valence cc-pCVQZ-F12 basis set in order to study convergence with respect to the basis set size. The contributions beyond the coupled-cluster level of the theory like Douglas-Kroll-Hess scalar relativistic Hamiltonian, diabatic Born-Oppenheimer corrections, and high-order electronic correlations have been included into the ab initio potential energy surfaces (PESs). It is shown that the theoretical band origins of CH3 converge gradually to the experimental values when applying the ab initio PESs using the aug-cc-pCVXZ [X = T, Q, and 5] basis sets. For the first time, all available experimental band origins of the gaseous CH3 are reproduced within an accuracy of 0.2 cm-1 using a newly developed PES extrapolated to the complete basis set limit [CBS(TQ5Z)]. The reached accuracy is one order of magnitude better than that of the best available calculations. A new theoretical infrared line list was generated for astrophysical applications using an ab initio dipole moment surface computed at the RHF-UCCSD(T)/aug-cc-pCVQZ level of the theory. The manifestation of a large-amplitude motion in CH3 is also discussed.
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Affiliation(s)
- Oleg Egorov
- Laboratory of Theoretical Spectroscopy, V.E. Zuev Institute of Atmospheric Optics SB RAS 1, Akademician Zuev Sq., Tomsk 634055 Russia
| | - Michaël Rey
- Groupe de Spectrométrie Moléculaire et Atmosphérique UMR CNRS 7331, UFR Sciences BP 1039, 51687 Reims Cedex 2, France
| | - Andrei V Nikitin
- Laboratory of Theoretical Spectroscopy, V.E. Zuev Institute of Atmospheric Optics SB RAS 1, Akademician Zuev Sq., Tomsk 634055 Russia
| | - Dominika Viglaska
- Groupe de Spectrométrie Moléculaire et Atmosphérique UMR CNRS 7331, UFR Sciences BP 1039, 51687 Reims Cedex 2, France
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2
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Chordiya K, Simkó I, Szidarovszky T, Upadhyay Kahaly M. Achieving high molecular alignment and orientation for CH[Formula: see text]F through manipulation of rotational states with varying optical and THz laser pulse parameters. Sci Rep 2022; 12:8280. [PMID: 35585150 PMCID: PMC9117237 DOI: 10.1038/s41598-022-10326-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 03/30/2022] [Indexed: 11/17/2022] Open
Abstract
Increasing interest in the fields of high-harmonics generation, laser-induced chemical reactions, and molecular imaging of gaseous targets demands high molecular "alignment" and "orientation" (A&O). In this work, we examine the critical role of different pulse parameters on the field-free A&O dynamics of the CH[Formula: see text]F molecule, and identify experimentally feasible optical and THz range laser parameters that ensure maximal A&O for such molecules. Herein, apart from rotational temperature, we investigate effects of varying pulse parameters such as, pulse duration, intensity, frequency, and carrier envelop phase (CEP). By analyzing the interplay between laser pulse parameters and the resulting rotational population distribution, the origin of specific A&O dynamics was addressed. We could identify two qualitatively different A&O behaviors and revealed their connection with the pulse parameters and the population of excited rotational states. We report here the highest alignment of [Formula: see text] and orientation of [Formula: see text] for CH[Formula: see text]F molecule at 2 K using a single pulse. Our study should be useful to understand different aspects of laser-induced unidirectional rotation in heteronuclear molecules, and in understanding routes to tune/enhance A&O in laboratory conditions for advanced applications.
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Affiliation(s)
- Kalyani Chordiya
- ELI-ALPS, ELI-HU Non-Profit Ltd., Szeged, Hungary
- Institute of Physics, University of Szeged, Dóm tér 9, Szeged, 6720 Hungary
| | - Irén Simkó
- Institute of Chemistry, ELTE Eötvös Loránd University, Budapest, Hungary
- ELKH-ELTE Complex Chemical Systems Research Group, Budapest, Hungary
| | - Tamás Szidarovszky
- Institute of Chemistry, ELTE Eötvös Loránd University, Budapest, Hungary
- ELKH-ELTE Complex Chemical Systems Research Group, Budapest, Hungary
| | - Mousumi Upadhyay Kahaly
- ELI-ALPS, ELI-HU Non-Profit Ltd., Szeged, Hungary
- Institute of Physics, University of Szeged, Dóm tér 9, Szeged, 6720 Hungary
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Dobulis MA, Thompson MC, Jarrold CC. Identification of Isoprene Oxidation Reaction Products via Anion Photoelectron Spectroscopy. J Phys Chem A 2021; 125:10089-10102. [PMID: 34755517 DOI: 10.1021/acs.jpca.1c08176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present a study on the oxidation of isoprene under several different conditions that may model both atmospheric and combustion chemistry. Anions, formed by passing isoprene/oxidant gas mixtures through a pulsed discharge generating a range of species, are separated via mass spectrometry and characterized by anion photoelectron (PE) spectroscopy supported by computations. Specifically, a UV-irradiated isoprene/O2 mixture, which additionally produces O3, and an isoprene/O2/H2 mixture, which generates •OH when passed through the discharge, were sampled. The mass spectra of ions generated under both conditions show the production of intact molecular ions, ion-molecule complexes (e.g., O2-, O4-, and O2-·isoprene), and singly deprotonated species (e.g., deprotonated isoprene, C5H7-). In addition, both smaller and oxidized fragments are observed using both gas mixtures, though relative abundances differ. From the UV-irradiated isoprene/O2 gas mixture, additional intact molecular products of reactions initiated by ozonolysis of isoprene, methylglyoxal, and dimethylglyoxal were observed. Fragmentation and oxidation of isoprene observed in both gas mixtures included species with m/z 39, 53, 67, 69, and 83 that we attribute to a series of alkyl- and alkenoxide-based anions. The coexistence of intact molecules and complexes with fragments and reaction products demonstrates the versatility of this ion source as a simple and efficient anion formation method for studying species that may be relevant in atmospheric and combustion chemistry.
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Affiliation(s)
- Marissa A Dobulis
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Michael C Thompson
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Caroline Chick Jarrold
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
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Straňák P, Ploenes L, Hofsäss S, Dulitz K, Stienkemeier F, Willitsch S. Development and characterization of high-repetition-rate sources for supersonic beams of fluorine radicals. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:103203. [PMID: 34717376 DOI: 10.1063/5.0065498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 09/24/2021] [Indexed: 06/13/2023]
Abstract
We present and compare two high-pressure, high-repetition-rate electric-discharge sources for the generation of supersonic beams of fluorine radicals. The sources are based on dielectric-barrier-discharge (DBD) and plate-discharge units attached to a pulsed solenoid valve. The corrosion-resistant discharge sources were operated with fluorine gas seeded in helium up to backing pressures as high as 30 bars. We employed a (3 + 1) resonance-enhanced multiphoton ionization combined with velocity-map imaging for the optimization, characterization, and comparison of the fluorine beams. Additionally, universal femtosecond-laser-ionization detection was used for the characterization of the discharge sources at experimental repetition rates up to 200 Hz. Our results show that the plate discharge is more efficient in F2 dissociation than the DBD by a factor between 8 and 9, whereas the DBD produces internally colder fluorine radicals.
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Affiliation(s)
- Patrik Straňák
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| | - Ludger Ploenes
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| | - Simon Hofsäss
- Institute of Physics, University of Freiburg, Hermann-Herder-Straße 3, 79104 Freiburg, Germany
| | - Katrin Dulitz
- Institute of Physics, University of Freiburg, Hermann-Herder-Straße 3, 79104 Freiburg, Germany
| | - Frank Stienkemeier
- Institute of Physics, University of Freiburg, Hermann-Herder-Straße 3, 79104 Freiburg, Germany
| | - Stefan Willitsch
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
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Ploenes L, Straňák P, Gao H, Küpper J, Willitsch S. A novel crossed-molecular-beam experiment for investigating reactions of state- and conformationally selected strong-field-seeking molecules. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1965234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- L. Ploenes
- Department of Chemistry, University of Basel, Basel, Switzerland
| | - P. Straňák
- Department of Chemistry, University of Basel, Basel, Switzerland
| | - H. Gao
- Department of Chemistry, University of Basel, Basel, Switzerland
| | - J. Küpper
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
- Center for Ultrafast Imaging, Universität Hamburg, Hamburg, Germany
- Department of Physics, Universität Hamburg, Hamburg, Germany
- Department of Chemistry, Universität Hamburg, Hamburg, Germany
| | - S. Willitsch
- Department of Chemistry, University of Basel, Basel, Switzerland
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Sixt T, Guan J, Tsoukala A, Hofsäss S, Muthu-Arachchige T, Stienkemeier F, Dulitz K. Preparation of individual magnetic sub-levels of 4He(2 3S 1) in a supersonic beam using laser optical pumping and magnetic hexapole focusing. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:073203. [PMID: 34340447 DOI: 10.1063/5.0048323] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 06/14/2021] [Indexed: 06/13/2023]
Abstract
We compare two different experimental techniques for the magnetic-sub-level preparation of metastable 4He in the 23S1 level in a supersonic beam, namely, magnetic hexapole focusing and optical pumping by laser radiation. At a beam velocity of v = 830 m/s, we deduce from a comparison with a particle trajectory simulation that up to 99% of the metastable atoms are in the MJ″ = +1 sub-level after magnetic hexapole focusing. Using laser optical pumping via the 23P2-23S1 transition, we achieve a maximum efficiency of 94% ± 3% for the population of the MJ″ = +1 sub-level. For the first time, we show that laser optical pumping via the 23P1-23S1 transition can be used to selectively populate each of the three MJ″ sub-levels (MJ″ = -1, 0, +1). We also find that laser optical pumping leads to higher absolute atom numbers in specific MJ″ sub-levels than magnetic hexapole focusing.
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Affiliation(s)
- Tobias Sixt
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Jiwen Guan
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Alexandra Tsoukala
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Simon Hofsäss
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | | | - Frank Stienkemeier
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Katrin Dulitz
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
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Dulitz K, van den Beld-Serrano M, Stienkemeier F. Single-Source, Collinear Merged-Beam Experiment for the Study of Reactive Neutral–Neutral Collisions. J Phys Chem A 2020; 124:3484-3493. [DOI: 10.1021/acs.jpca.0c00608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Katrin Dulitz
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | | | - Frank Stienkemeier
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
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Grzesiak J, Momose T, Stienkemeier F, Mudrich M, Dulitz K. Penning collisions between supersonically expanded metastable He atoms and laser-cooled Li atoms. J Chem Phys 2019; 150:034201. [DOI: 10.1063/1.5063709] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Jonas Grzesiak
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Takamasa Momose
- Department of Chemistry, The University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Frank Stienkemeier
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Marcel Mudrich
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
| | - Katrin Dulitz
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
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