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Wang J, Wang P, Mo Y. Spectra and Predissociation Dynamics of the 4pσB'' 1∑ u+ and 4pπD' 1Π u States of D 2. J Phys Chem A 2022; 126:4810-4817. [PMID: 35852949 DOI: 10.1021/acs.jpca.2c04165] [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 spectra and predissociation dynamics of the Rydberg states 4pσB″1∑u+(υ'=2) and 4pπD'1Πu±(υ'=1) of the D2 molecule have been studied by a combination of XUV laser pump, UV laser probe, and velocity map imaging methods. The D(2l) fragment yield spectrum and the D2 excitation spectrum have been measured. Although the predissociation rates were found to be small and comparable to the radiative decay rates, the D(2l) fragments were observed for all the Rydberg states. The measured D(2l) fragment angular distributions are in good agreement with a reported model that has an analytical formula for anisotropy parameters. The results demonstrated that the 4pσB″1∑u+ and 4pπD'1Π u+ states dissociate via direct and indirect coupling with an 1∑u+ state, respectively. For predissociation of the 4pσB″1∑u+ state, the experimental data showed that D(1s) + D(2s) is the main channel, supporting previous theoretical predictions that the predissociation occurs by coupling to the vibrational continuum of the 3pσB'1∑u+ state.
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Affiliation(s)
- Jie Wang
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
- National Innovation Institute of Defense Technology, Academy of Military Sciences of People's Liberation Army, China, Beijing 100071, China
| | - Peng Wang
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
| | - Yuxiang Mo
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
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Wang L, Mo Y. Photodissociation of HCl in the photon energy range 14.6-15.0 eV: Channel-resolved branching ratios and fragment angular distributions. J Chem Phys 2020; 152:014309. [PMID: 31914760 DOI: 10.1063/1.5140614] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
For the HCl molecule, four photodissociation channels are open in the excitation energy region 14.6-15.0 eV: H(2s) + Cl(2P3/2), H(2p) + Cl(2P3/2), H(2s) + Cl(2P1/2), and H(2p) + Cl(2P1/2). We measured the fragment angular distributions and the branching ratios of the four dissociation channels by using the extreme ultraviolet laser pump and UV laser probe, delay-time-curve, and velocity map imaging methods. The channel-resolved fragment angular distributions and fragment yield spectra show that various Rydberg states (superexcited states) contribute to the absorption cross sections, including the [A2Σ+]4pσ, [A2Σ+]4pπ, [A2Σ+]3dσ, [A2Σ+]3dπ, and [A2Σ+]5sσ states. Most of the H(2s) + Cl(2P1/2) channels correlate with the 1Σ+ states, while the other channels correlate with mixing excitations of the 1Σ+ and 1,3Π states. The channel branching ratios are dependent on the excitation energies. When the four channels are open, the channel branching ratios of H(2s) + Cl(2P3/2) and H(2p) + Cl(2P1/2) are small. Based on the recent ab initio potential energy curves, the Rydberg states converging to the ion-core A2Σ+ are proposed to be predissociated by the nuclear vibrational continua of the Rydberg states converging to the ion-core X2Π.
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Affiliation(s)
- Lingxuan Wang
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
| | - Yuxiang Mo
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
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Trivikram TM, Salumbides EJ, Jungen C, Ubachs W. Excitation of H 2 at large internuclear separation: outer well states and continuum resonances. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1599457] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- T. M. Trivikram
- Department of Physics and Astronomy, and LaserLaB, Vrije Universiteit, Amsterdam, The Netherlands
| | - E. J. Salumbides
- Department of Physics and Astronomy, and LaserLaB, Vrije Universiteit, Amsterdam, The Netherlands
| | - Ch. Jungen
- Department of Physics and Astronomy, University College London, London, United Kingdom
| | - W. Ubachs
- Department of Physics and Astronomy, and LaserLaB, Vrije Universiteit, Amsterdam, The Netherlands
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Affiliation(s)
- M. Glass-Maujean
- Laboratoire D'etudes Du Rayonnement et De La Matière en Astrophysique et Atmosphères, Sorbonne Universités, Observatoire de Paris, CNRS, Paris, France
| | - H. Schmoranzer
- Fachbereich Physik, Technische Universität Kaiserslautern, Kaiserslautern, Germany
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Wang J, Meng Q, Mo Y. Oscillation of Branching Ratios Between the D(2s)+D(1s) and the D(2p)+D(1s) Channels in Direct Photodissociation of D_{2}. PHYSICAL REVIEW LETTERS 2017; 119:053002. [PMID: 28949706 DOI: 10.1103/physrevlett.119.053002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Indexed: 06/07/2023]
Abstract
The direct photodissociation of D_{2} at excitation energies above 14.76 eV occurs via two channels, D(2s)+D(1s) and D(2p)+D(1s). The branching ratios between the two have been measured from the dissociation threshold to 3200 cm^{-1} above it, and it is found that they show cosine oscillations as a function of the fragment wave vector magnitudes. The oscillation is due to an interference effect and can be simulated using the phase difference between the wave functions of the two channels, analogous to Young's double-slit experiment. By fitting the measured branching ratios, we have determined the depths and widths of the effective spherical potential wells related to the two channels, which are in agreement with the effective depths and widths of the ab initio interaction potentials. The results of this Letter illustrate the importance of the relative phase between the fragments in controlling the branching ratios of the photodissociation channels.
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Affiliation(s)
- Jie Wang
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
| | - Qingnan Meng
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
| | - Yuxiang Mo
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
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Hollenstein U, Schmutz H, Agner JA, Sommavilla M, Merkt F. Vacuum-ultraviolet frequency-modulation spectroscopy. J Chem Phys 2017; 146:014201. [PMID: 28063449 DOI: 10.1063/1.4973011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Frequency-modulation (FM) spectroscopy has been extended to the vacuum-ultraviolet (VUV) range of the electromagnetic spectrum. Coherent VUV laser radiation is produced by resonance-enhanced sum-frequency mixing (νVUV=2νUV+ν2) in Kr and Xe using two near-Fourier-transform-limited laser pulses of frequencies νUV and ν2. Sidebands generated in the output of the second laser (ν2) using an electro-optical modulator operating at the frequency νmod are directly transferred to the VUV and used to record FM spectra. Demodulation is demonstrated both at νmod and 2νmod. The main advantages of the method compared to VUV absorption spectroscopy are its background-free nature, the fact is that its implementation using table-top laser equipment is straightforward and that it can be used to record VUV absorption spectra of cold samples in skimmed supersonic beams simultaneously with laser-induced-fluorescence and photoionization spectra. To illustrate these advantages, we present VUV FM spectra of Ar, Kr, and N2 in selected regions between 105000 cm-1 and 122000 cm-1.
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Affiliation(s)
- U Hollenstein
- Laboratorium für Physikalische Chemie, ETH Zürich, 8093 Zürich, Switzerland
| | - H Schmutz
- Laboratorium für Physikalische Chemie, ETH Zürich, 8093 Zürich, Switzerland
| | - J A Agner
- Laboratorium für Physikalische Chemie, ETH Zürich, 8093 Zürich, Switzerland
| | - M Sommavilla
- Laboratorium für Physikalische Chemie, ETH Zürich, 8093 Zürich, Switzerland
| | - F Merkt
- Laboratorium für Physikalische Chemie, ETH Zürich, 8093 Zürich, Switzerland
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Trivikram TM, Niu ML, Wcisło P, Ubachs W, Salumbides EJ. Precision measurements and test of molecular theory in highly excited vibrational states of H 2 ( v = 11). APPLIED PHYSICS. B, LASERS AND OPTICS 2016; 122:294. [PMID: 32336882 PMCID: PMC7154793 DOI: 10.1007/s00340-016-6570-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 11/04/2016] [Indexed: 06/08/2023]
Abstract
Accurate E F 1 Σ g + - X 1 Σ g + transition energies in molecular hydrogen were determined for transitions originating from levels with highly excited vibrational quantum number, v = 11, in the ground electronic state. Doppler-free two-photon spectroscopy was applied on vibrationally excited H 2 ∗ , produced via the photodissociation of H2S, yielding transition frequencies with accuracies of 45 MHz or 0.0015 cm-1. An important improvement is the enhanced detection efficiency by resonant excitation to autoionizing 7 p π electronic Rydberg states, resulting in narrow transitions due to reduced ac-Stark effects. Using known EF level energies, the level energies of X(v = 11, J = 1, 3-5) states are derived with accuracies of typically 0.002 cm-1. These experimental values are in excellent agreement with and are more accurate than the results obtained from the most advanced ab initio molecular theory calculations including relativistic and QED contributions.
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Affiliation(s)
- T. Madhu Trivikram
- Department of Physics and Astronomy, LaserLaB, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - M. L. Niu
- Department of Physics and Astronomy, LaserLaB, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - P. Wcisło
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziądzka 5, 87-100 Toruń, Poland
| | - W. Ubachs
- Department of Physics and Astronomy, LaserLaB, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - E. J. Salumbides
- Department of Physics and Astronomy, LaserLaB, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
- Department of Physics, University of San Carlos, 6000 Cebu City, Philippines
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