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Spin‐Orbit Ab Initio Investigation of the Ultraviolet Photolysis of Diiodomethane
Author(s) -
Liu YaJun,
De Vico Luca,
Lindh Roland,
Fang WeiHai
Publication year - 2007
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200600737
Subject(s) - photodissociation , diiodomethane , chemistry , ab initio , singlet state , complete active space , ab initio quantum chemistry methods , intersystem crossing , ground state , isomerization , excited state , atomic physics , photochemistry , computational chemistry , density functional theory , physics , basis set , molecule , biochemistry , surface energy , organic chemistry , catalysis
The UV photodissociation (<5 eV) of diiodomethane (CH 2 I 2 ) is investigated by spin‐orbit ab initio calculations. The experimentally observed photodissociation channels in the gas and condensed phases are clearly assigned by multi‐state second‐order multiconfigurational perturbation theory in conjunction with spin‐orbit interaction through complete active space‐state interaction potential energy curves. The calculated results indicate that the fast dissociations of the first two singlet states of CH 2 I 2 and CH 2 II lead to geminate‐radical products, CH 2 I . +I( 2 P 3/2 ) or CH 2 I . + I*( 2 P 1/2 ). The recombination process from CH 2 II to CH 2 I 2 is explained by an isomerization process and a secondary photodissociation reaction of CH 2 II. Finally, the study reveals that spin‐orbits effects are significant in the quantitative analysis of the electronic spectrum of the CH 2 II species.