1
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Chi X, Jiang P, Zhu Q, Cheng M, Gao H. Photodissociation branching ratios for several absorption bands of 12C 16O from 108,500 to 109,220 cm −1. Mol Phys 2021. [DOI: 10.1080/00268976.2020.1718228] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Xiaoping Chi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, People’s Republic of China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, People’s Republic of China
| | - Pan Jiang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, People’s Republic of China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, People’s Republic of China
| | - Qihe Zhu
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, People’s Republic of China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, People’s Republic of China
| | - Min Cheng
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, People’s Republic of China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, People’s Republic of China
| | - Hong Gao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, People’s Republic of China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, People’s Republic of China
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2
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Gao H. Molecular photodissociation in the vacuum ultraviolet region: implications for astrochemistry and planetary atmospheric chemistry. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1861354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Hong Gao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing, People’s Republic of China
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3
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Guan L, Jiang P, Zhang G, Yin T, Chi X, Bai Y, Cheng M, Gao H. Vacuum Ultraviolet Photodissociation Branching Ratios of 12C 16O, 13C 16O, and 12C 18O from 100500 to 102320 cm -1. J Phys Chem A 2020; 124:9382-9391. [PMID: 33146529 DOI: 10.1021/acs.jpca.0c08026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The C+ ion photofragment spectra and photodissociation branching ratios into the two energetically available channels, C(1D) + O(3P) and C(3P) + O(3P), have been obtained for the three CO isotopologues, 12C16O, 13C16O, and 12C18O, in the vacuum ultraviolet range 100500-102320 cm-1. The two vibronic states of 1Σ+ symmetry, F(3dσ) 1Σ+(υ' = 1) and J(4sσ) 1Σ+(υ' = 0), predominantly dissociate into the lowest channel C(3P) + O(3P) through interactions with the repulsive D'1Σ+ state. All three vibronic states of 1Π symmetry, E'1Π(υ' = 1, 2) and G(3dπ) 1Π(υ' = 0), dissociate into both of the channels above. The photodissociation branching ratios into the channel C(1D) + O(3P) for E'1Π(υ' = 1, 2) are found to be independent of both the rotational quantum number and e/f parity, while those for G(3dπ) 1Π(υ' = 0) strongly depend on the rotational quantum number, indicating very different predissociation pathways between the valence states E'1Π(υ' = 1, 2) and the Rydberg state G(3dπ) 1Π(υ' = 0). The potential energy curves of CO in the aforementioned energy range and below have recently been well constructed due to a series of interplays between high-resolution spectroscopic studies and theoretical calculations; the photodissociation branching ratios measured in this study can provide further benchmarks for future theoretical investigations which aim to understand the detailed predissociation dynamics of CO.
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Affiliation(s)
- Lichang Guan
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Pan Jiang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guodong Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tonghui Yin
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoping Chi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yu Bai
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Min Cheng
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hong Gao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
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4
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Jiang P, Chi X, Zhang G, Yin T, Guan L, Cheng M, Gao H. Reinvestigation of the Rydberg W 1Π(ν = 1) level of 12C 16O, 13C 16O, and 12C 18O through rotationally dependent photodissociation branching ratio measurements. J Chem Phys 2020; 152:234308. [PMID: 32571069 DOI: 10.1063/5.0009931] [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
A recent high resolution photoabsorption study revealed that the Rydberg W1Π(ν = 1) level of carbon monoxide (CO) is perturbed by the valence E″1Π(ν = 0) level, and the predissociation linewidth shows drastic variation at the crossing point due to the interference effect [Heays et al., J. Chem. Phys. 141(14), 144311 (2014)]. Here, we reinvestigate the Rydberg W1Π(ν = 1) level for the three CO isotopologues, 12C16O, 13C16O, and 12C18O, by measuring the rotationally dependent photodissociation branching ratios. The C+ ion photofragment spectra obtained here reproduce the recent high resolution photoabsorption spectra very well, including the presence of the valence E″1Π(ν = 0) level. The photodissociation branching ratios into the spin-forbidden channel C(1D) + O(3P) show sudden increases at the crossing point between the W1Π(ν = 1) and E″1Π(ν = 0) levels, which is in perfect accordance with the drastic variation of the linewidth observed in the recent spectroscopic study. Further analysis reveals that the partial predissociation rate into the lowest channel C(3P) + O(3P) shows a much more prominent decrease at the crossing point, which is caused by the interference effect between the W1Π(ν = 1) and E″1Π(ν = 0) levels, than that into the spin-forbidden channel C(1D) + O(3P), and this is the reason of the sudden increase as observed in the photodissociation branching ratio measurements. We hope that the current experimental investigation will stimulate further theoretical studies, which could thoroughly address all the experimental observations in a quantitative way.
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Affiliation(s)
- Pan Jiang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiaoping Chi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Guodong Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Tonghui Yin
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Lichang Guan
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Min Cheng
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Hong Gao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
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5
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Gao H, Song Y, Jackson WM, Ng CY. Photodissociation branching ratios of 12C 16O from 108000 cm −1 to 113200 cm -1 measured by two-color VUV-VUV laser pump-probe time-slice velocity-map ion imaging method: Observation of channels for producing O( 1D). CHINESE J CHEM PHYS 2020. [DOI: 10.1063/1674-0068/cjcp1911199] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Hong Gao
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences,
Beijing 100190, China
- Department of Chemistry, University of California, Davis CA 95616, USA
| | - Yu Song
- Department of Chemistry, University of California, Davis CA 95616, USA
| | | | - Cheuk-Yiu Ng
- Department of Chemistry, University of California, Davis CA 95616, USA
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6
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Jiang P, Chi X, Zhu Q, Cheng M, Gao H. Channel-resolved rotationally dependent predissociation rate constants reveal the state-to-state dissociation dynamics of carbon monoxide in electronically excited states. Phys Chem Chem Phys 2020; 22:2549-2556. [PMID: 31942884 DOI: 10.1039/c9cp06351j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Rotational dependence of the total predissociation rate constants deduced from linewidth measurements in spectroscopic studies have often been used to predict the possible electronic coupling schemes in the photodissociation process of carbon monoxide (CO), while the intrinsic multi-channel characteristics of CO photodissociation make the prediction unreliable and sometimes misleading conclusions could be reached. Here, we demonstrate for the first time in the Rydberg 4p(2) and 5p(0) complexes region of 13C16O that absolute partial predissociation rate constants into each individual channel and their dependences on the rotational quantum numbers can be obtained through branching ratio measurements in combination with the total predissociation rate constants reported in spectroscopic studies. These channel-resolved rotationally dependent predissociation rate constants are found to unambiguously reveal the detailed state-to-state photodissociation dynamics of CO, which is not available from either the branching ratio or the total predissociation rate constant measurements individually.
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Affiliation(s)
- Pan Jiang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoping Chi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qihe Zhu
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Min Cheng
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hong Gao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100049, China
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7
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Jiang P, Chi X, Zhu Q, Cheng M, Gao H. Strong and selective isotope effect in the vacuum ultraviolet photodissociation branching ratios of carbon monoxide. Nat Commun 2019; 10:3175. [PMID: 31320624 PMCID: PMC6639306 DOI: 10.1038/s41467-019-11086-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 06/21/2019] [Indexed: 11/10/2022] Open
Abstract
Rare isotope (13C, 17O and 18O) substitutions can substantially change absorption line positions, oscillator strengths and photodissociation rates of carbon monoxide (CO) in the vacuum ultraviolet (VUV) region, which has been well accounted for in recent photochemical models for understanding the large isotopic fractionation effects that are apparent in carbon and oxygen in the solar system and molecular clouds. Here, we demonstrate a strong isotope effect associated with the VUV photodissociation of CO by measuring the branching ratios of 12C16O and 13C16O in the Rydberg 4p(2), 5p(0) and 5s(0) complex region. The measurements show that the quantum yields of electronically excited C atoms in the photodissociation of 13C16O are dramatically different from those of 12C16O, revealing strong isotope effect. This isotope effect strongly depends on specific quantum states of CO being excited, which implies that such effect must be considered in the photochemical models on a state by state basis.
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Affiliation(s)
- Pan Jiang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaoping Chi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qihe Zhu
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Min Cheng
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Hong Gao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
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8
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Jiang P, Chi X, Qi W, Zhu Q, Cheng M, Gao H. Rotational dependence of the branching ratios and fragment angular distributions for the photodissociation of 12C 16O in the Rydberg 4p(2) and 5p(0) complex region (92.84-93.37 nm). Phys Chem Chem Phys 2019; 21:14376-14386. [PMID: 30742166 DOI: 10.1039/c8cp07620k] [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
12C16O shows complicated absorption structures in the wavelength range of 92.84-93.37 nm caused by the mutual interactions among the Rydberg 4p(2) and 5p(0) complexes, and several diffuse valence states. Here, we systematically measured the branching ratios and fragment angular distributions for the photodissociation of 12C16O in the wavelength range using our mini-time-slice velocity-map imaging (mini-TSVMI) setup and a tunable vacuum ultraviolet (VUV) laser radiation source generated by the two-photon resonance-enhanced four-wave mixing scheme. Various patterns of rotational dependence for the photodissociation branching ratios have been observed for different vibronic states, and they are found to be consistent with previous spectroscopic investigations, revealing the complicated coupling schemes and predissociation dynamics in this region. Irregular angular distributions of the photofragments have been observed, especially in the Rydberg 5p(0) complex region. This has been attributed to the simultaneous excitation of multiple states with different symmetries in this region. The newly observed underlying continuum in the Rydberg 5p(0) complex region has been directly detected in the present study, and it is found to be of 1Σ+ symmetry and dissociates predominantly into the C(3P) + O(3P) channel. This study generally confirms the results of previous spectroscopic studies from a different perspective, and adds new knowledge for understanding the complicated predissociation dynamics of 12C16O in the titled wavelength range.
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Affiliation(s)
- Pan Jiang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoping Chi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenke Qi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qihe Zhu
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
| | - Min Cheng
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
| | - Hong Gao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
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9
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Gao H, Ng CY. Quantum state-to-state vacuum ultraviolet photodissociation dynamics of small molecules. CHINESE J CHEM PHYS 2019. [DOI: 10.1063/1674-0068/cjcp1812290] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Hong Gao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Cheuk-Yiu Ng
- Department of Chemistry, University of California, Davis CA 95616, USA
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10
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Shi X, Gao H, Yin QZ, Chang YC, Wiens RC, Jackson WM, Ng CY. Branching Ratio Measurements of the Predissociation of 12C 16O by Time-Slice Velocity-Map Ion Imaging in the Energy Region from 106 250 to 107 800 cm -1. J Phys Chem A 2018; 122:8136-8142. [PMID: 30231612 DOI: 10.1021/acs.jpca.8b08058] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photodissociation of CO is a fundamental chemical mechanism for mass-independent oxygen isotope fractionation in the early Solar System. Branching ratios of photodissociation channels for individual bands quantitatively yield the trapping efficiencies of atomic oxygen resulting into oxides. We measured the branching ratios for the spin-forbidden and spin-allowed photodissociation channels of 12C16O in the vacuum ultraviolet (VUV) photon energy region from 106 250 to 107 800 cm-1 using the VUV laser time-slice velocity-map imaging photoion technique. The excitations to four 1Π bands and three 1Σ+ bands of 12C16O were identified and investigated. The branching ratios for the product channels C(3P) + O(3P), C(1D) + O(3P), and C(3P) + O(1D) of these predissociative states strongly depend on the electronic and vibrational states of CO being excited. By plotting the branching ratio of the spin-forbidden dissociation channels versus the excitation energy from 102 500 to 110 500 cm-1 that has been measured so far, the global pattern of the 1Π-3Π interaction that plays a key role in the predissociation of CO is revealed and discussed.
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Affiliation(s)
| | - Hong Gao
- Institute of Chemistry , Chinese Academy of Science , Beijing 100190 China
| | | | | | - Roger C Wiens
- Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
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11
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Branching Ratios in Vacuum Ultraviolet Photodissociation of CO and N2: Implications for Oxygen and Nitrogen Isotopic Compositions of the Solar Nebula. ACTA ACUST UNITED AC 2017. [DOI: 10.3847/1538-4357/aa8ee7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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12
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Lefebvre-Brion H, Kalemos A. Interpretation of the predissociation of the CO Rydberg W (1)Π (v = 1) level. J Chem Phys 2016; 144:134302. [PMID: 27059565 DOI: 10.1063/1.4945117] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
With the goal to interpret the experimental results obtained quite recently by Heays et al. [J. Chem. Phys. 141, 144311 (2014)] on the predissociation of the Rydberg W (1)Π (v = 1) vibrational level of the CO molecule, we report herein ab initio potential energy curves of some of its valence and Rydberg states of both (1)Π and (3)Π symmetry. Our results confirm that the above vibrational level is perturbed by a new electronic (1)Π state not observed until now. They correctly reproduce the linewidths of predissociation of the two interacting levels.
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Affiliation(s)
- H Lefebvre-Brion
- Institut des Sciences Moléculaires d'Orsay (ISMO), Bâtiment 210, Université Paris-Sud, 91405 Orsay Cedex, France
| | - A Kalemos
- Department of Chemistry, Laboratory of Physical Chemistry, National and Kapodistrian University of Athens, Athens 157 71, Greece
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13
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Lu Z, Gao H, Xu YT, Yang L, Lam CS, Benitez Y, Ng CY. High-Resolution Threshold Photoelectron Spectroscopy by Vacuum Ultraviolet Laser Velocity-Map-Imaging Method. CHINESE J CHEM PHYS 2016. [DOI: 10.1063/1674-0068/29/cjcp1512247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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14
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Lefebvre-Brion H, Majumder M. Isotopic dependence of the predissociations of the E(1)Π state of CO. J Chem Phys 2015; 142:164306. [PMID: 25933763 DOI: 10.1063/1.4918910] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The predissociations of the E(1)Π state of CO are again studied. They include both the background predissociation attributed to the continuum of the A(1)Π state and the accidental predissociation due to the k(3)Π state. They are calculated using a coupled equations method. The three components of the k state are introduced. These predissociations are studied for different isotopologues and are shown to decrease with increasing reduced mass, in agreement with the experimental results of Ubachs et al. [J. Chem. Phys. 113, 547 (2000)].
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Affiliation(s)
- H Lefebvre-Brion
- Institut des Sciences Moléculaires d'Orsay (ISMO), Bât. 213, Université Paris-Sud, 91405 Orsay Cedex, France
| | - M Majumder
- Department of Chemistry, Missouri University of Science and Technology, Rolla, Missouri 65409-0010, USA
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15
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Gao H, Song Y, Chang YC, Shi X, Yin QZ, Wiens RC, Jackson WM, Ng CY. Branching ratio measurements for vacuum ultraviolet photodissociation of 12C16O. J Phys Chem A 2013; 117:6185-95. [PMID: 23510317 DOI: 10.1021/jp400412n] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The branching ratios for the spin-forbidden photodissociation channels of (12)C(16)O in the vacuum ultraviolet (VUV) photon energy region from 102,500 (12.709 eV) to 106,300 cm(-1) (13.180 eV) have been investigated using the VUV laser time-slice velocity-map imaging photoion technique. The excitations to three (1)Σ(+) and six (1)Π Rydberg-type states, including the progression of W(3sσ) (1)Π(v' = 0, 1, and 2) vibrational levels of CO, have been identified and investigated. The branching ratios for the product channels C((3)P) + O((3)P), C((1)D) + O((3)P), and C((3)P) + O((1)D) of these predissociative states are found to depend on the electronic, vibrational, and rotational states of CO being excited. Rotation and e/f-symmetry dependences of the branching ratios into the spin-forbidden channels have been confirmed for several of the (1)Π states, which can be explained using the heterogeneous interaction with the repulsive D'(1)Σ(+) state. The percentage of the photodissociation into the spin-forbidden channels is found to increase with increasing the rotational quantum number for the K(4pσ) (1)Σ(+) (v' = 0) state. This has been rationalized using a (1)Σ(+) to (1)Π to (3)Π coupling scheme, where the final (3)Π state is a repulsive valence state correlating to the spin-forbidden channel.
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Affiliation(s)
- Hong Gao
- Department of Chemistry, University of California, Davis, California 95616, USA
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16
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Gao H, Song Y, Jackson WM, Ng CY. Communication: State-to-state photodissociation study by the two-color VUV-VUV laser pump-probe time-slice velocity-map-imaging-photoion method. J Chem Phys 2013; 138:191102. [DOI: 10.1063/1.4807302] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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17
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Chakraborty S, Davis RD, Ahmed M, Jackson TL, Thiemens MH. Oxygen isotope fractionation in the vacuum ultraviolet photodissociation of carbon monoxide: wavelength, pressure, and temperature dependency. J Chem Phys 2012; 137:024309. [PMID: 22803538 DOI: 10.1063/1.4730911] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Several absorption bands exist in the vacuum ultraviolet (VUV) region of carbon monoxide (CO). Emission spectra indicate that these bands are all predissociative. Experimental results of CO photodissociation by vacuum ultraviolet photons (90 to 108 nm; ∼13 to 11 eV) from the Advanced Light Source synchrotron by measurement of the oxygen isotopic composition of the products are presented here. A large (few hundred per mil) range of oxygen isotopic compositions are observed in the CO photodissociation product and are wavelength dependent. Slope values (δ('17)O/δ('18)O) ranging from 0.72 to 1.36 were observed in the oxygen three-isotope space (δ('18)O vs. δ('17)O), which anti-correlated with increasing synchrotron photon energy, and indicates a dependency on the upper electronic state specific dissociation dynamics (e.g., perturbation and coupling associated with a particular state). An unprecedented magnitude in isotope fractionation was observed for photodissociation at 105 and 107 nm and is found to be associated with accidental predissociation of the vibrational states (ν = 0 and 1) for the upper electronic state E(1)Π. A significant temperature dependency in oxygen isotopic fractionation was observed, indicating a rotational level dependency in the predissociation process.
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Affiliation(s)
- Subrata Chakraborty
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0356, USA.
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18
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Gao H, Song Y, Yang L, Shi X, Yin QZ, Ng CY, Jackson WM. Branching ratio measurements of the predissociation of 12C16O by time-slice velocity-map ion imaging in the energy region from 108,000 to 110,500 cm(-1). J Chem Phys 2012; 137:034305. [PMID: 22830700 DOI: 10.1063/1.4734018] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Direct branching ratio measurements of the three lowest dissociation channels of (12)C(16)O that produce C((3)P) + O((3)P), C((1)D) + O((3)P), and C((3)P) + O((1)D) are reported in the vacuum ultraviolet region from 108,000 cm(-1) (92.59 nm) to 110,500 cm(-1) (90.50 nm) using the time-slice velocity-map ion imaging and nonlinear resonant four-wave mixing techniques. Rotationally, resolved carbon ion yield spectra for both (1)Σ(+) and (1)Π bands of CO in this region have been obtained. Our measurements using this technique show that the branching ratio in this energy region, especially the relative percentages of the two spin-forbidden channels, is strongly dependent on the particular electronic and vibrational energy levels of CO that are excited.
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Affiliation(s)
- Hong Gao
- Department of Chemistry, University of California Davis, Davis, California 95616, USA
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Gao H, Pan Y, Yang L, Zhou J, Ng CY, Jackson WM. Time-slice velocity-map ion imaging studies of the photodissociation of NO in the vacuum ultraviolet region. J Chem Phys 2012; 136:134302. [DOI: 10.1063/1.3696897] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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