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Title: Ab initio reaction pathways for photodissociation and isomerization of nitromethane on four singlet potential energy surfaces with three roaming paths

Photodissociation pathways of nitromethane following π → π{sup *} electronic excitation are reported. The potential energy surfaces for four lowest singlet states are explored, and structures of many intermediates, dissociation limits, transition states, and minimum energy conical intersections were determined using the automated searching algorism called the global reaction route mapping strategy. Geometries are finally optimized at CASSCF(14e,11o) level and energies are computed at CAS(14o,11e)PT2 level. The calculated preferable pathways and important products qualitatively explain experimental observations. The major photodissociation product CH{sub 3} and NO{sub 2} ({sup 2}B{sub 2}) is formed by direct dissociation from the S{sub 1} state. Important pathways involving S{sub 1} and S{sub 0} states for production of various dissociation products CH{sub 3}NO + O ({sup 1}D), CH{sub 3}O(X{sup 2}E) + NO (X{sup 2}Π), CH{sub 2}NO + OH, and CH{sub 2}O + HNO, as well as various isomerization pathways have been identified. Three roaming processes also have been identified: the O atom roaming in O dissociation from CH{sub 3}NO{sub 2}, the OH radical roaming in OH dissociation from CH{sub 2}N(O)(OH), and the NO roaming in NO dissociation from CH{sub 3}ONO.
Authors:
; ;  [1] ;  [2]
  1. Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103 (Japan)
  2. Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan)
Publication Date:
OSTI Identifier:
22311294
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 24; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ATOMS; CALCIUM SULFIDES; DISSOCIATION; EXCITATION; FORMALDEHYDE; HYDROXYL RADICALS; ISOMERIZATION; NITRIC OXIDE; NITROGEN DIOXIDE; NITROMETHANE; PHOTOLYSIS; POTENTIAL ENERGY; SURFACES