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Title: Nonadiabatic photodissociation dynamics of the hydroxymethyl radical via the 2 2 A (3 s ) Rydberg state: A four-dimensional quantum study

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [1]
  1. Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
  2. Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1363703
Grant/Contract Number:
SC0015997
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 146; Journal Issue: 22; Related Information: CHORUS Timestamp: 2018-02-14 11:29:16; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Xie, Changjian, Malbon, Christopher, Yarkony, David R., and Guo, Hua. Nonadiabatic photodissociation dynamics of the hydroxymethyl radical via the 2 2 A (3 s ) Rydberg state: A four-dimensional quantum study. United States: N. p., 2017. Web. doi:10.1063/1.4985147.
Xie, Changjian, Malbon, Christopher, Yarkony, David R., & Guo, Hua. Nonadiabatic photodissociation dynamics of the hydroxymethyl radical via the 2 2 A (3 s ) Rydberg state: A four-dimensional quantum study. United States. doi:10.1063/1.4985147.
Xie, Changjian, Malbon, Christopher, Yarkony, David R., and Guo, Hua. Wed . "Nonadiabatic photodissociation dynamics of the hydroxymethyl radical via the 2 2 A (3 s ) Rydberg state: A four-dimensional quantum study". United States. doi:10.1063/1.4985147.
@article{osti_1363703,
title = {Nonadiabatic photodissociation dynamics of the hydroxymethyl radical via the 2 2 A (3 s ) Rydberg state: A four-dimensional quantum study},
author = {Xie, Changjian and Malbon, Christopher and Yarkony, David R. and Guo, Hua},
abstractNote = {},
doi = {10.1063/1.4985147},
journal = {Journal of Chemical Physics},
number = 22,
volume = 146,
place = {United States},
year = {Wed Jun 14 00:00:00 EDT 2017},
month = {Wed Jun 14 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4985147

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  • We have determined the I 2P3/2 and 2P1/2 branching fractions following the photodissociation of methyl iodide (CH3I) via a number of vibronic bands associated with themore » $$\tilde{B}$$ (2E3/2)6s Rydberg state at excitation wavelengths between 201.2 and 192.7 nm. Vacuum ultraviolet light at 118.2 nm was used to ionize both the product iodine atoms and the methyl radical cofragments, and velocity map ion imaging was used to determine the product translational energy distributions and angular distributions. The known relative photoionization cross sections for I 2P3/2 and 2P1/2 at 118.2 nm were used to determine the corresponding branching fractions. The results extend our earlier work at 193 nm by Xu et al. (J. Chem. Phys. 2013, 139, 214310), and complement the closely related work of Gonz├ílez et al. (J. Chem. Phys. 2011, 135, 021102). We find that for most of the excited vibronic levels of the $$\tilde{B}$$ state studied, the I 2P3/2 branching ratio is small, but nonzero, and that this channel is associated with internally excited CH3 radicals. The results are discussed in relation to the recent theoretical results of Alekseyev et al. (J. Chem. Phys. 2011, 134, 044303).« less
  • The photodissociation dynamics of methyl radical have been investigated at 193.3 nm using photofragment translational spectroscopy. The formation of CH[sub 2] and H([sup 2][ital S]) was the only dissociation pathway observed. Although it is not possible to assign the spin state of the methylene unambiguously, we believe that methylene is produced predominately in the [ital [tilde a]] [sup 1][ital A][sub 1] excited state. The translational energy distribution of the products is peaked at [similar to]13 kcal/mole which is consistent with the magnitude of the exit barrier on the excited state potential energy surface. The breadth of the distribution suggests thatmore » the methyl radicals dissociate from a wide range of geometries. From the photofragment angular distribution an anisotropy parameter of [beta]=[minus]0.9[plus minus]0.1 was determined.« less
  • Photodissociation of hydroxymethyl (H{sub 2}COD) from the first excited state, a Rydberg 3s state, can produce either H+HCOD or H{sub 2}CO+D. These processes involve a seam of conical intersections. An analysis of the seam is reported based on a pointwise determination of the three gradient vectors that characterize a conical intersection: the energy difference gradient and the coupling gradient, which span the branching space, and the gradient of the average energy. These data are used to understand why H, but not D is produced at energies near threshold, the difference in the recoil anisotropy for H and D dissociation, andmore » whether H or D will be produced impulsively or after formation of an intermediate complex.« less
  • Photodissociation of diatomic molecules to open-shell atoms is shown to be very strongly affected by nonadiabatic interactions when the photon energy is just above the threshold for dissociation. The energy dependences of photodissociation cross sections and various anisotropy parameters exhibit a wealth of structure in conformity with their theoretical predictions that nonadiabatic interactions between molecular states, approaching the same atomic term limit, lead to the emergence of resonance features in the spectra. Some of these features are associated with Feshbach and shape resonances on states that carry no oscillator strength in zeroth order. As an example, they consider the photodissociationmore » cross sections for the production of individual C/sup +/(/sup 2/P/sub 3/2,1/2/) states from selected initial CH/sup +/ levels and the fragment angular distribution, orientation, and alignment. They discuss how totally oriented fragments can be produced by near-threshold photodissociation in a magnetic field.« less