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The Photochemistry of Ch 3 I in Various Matrices at Low Temperature
Author(s) -
Yeh SyunRu,
Chang Hua
Publication year - 1989
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.198900077
Subject(s) - chemistry , iodine , iodide , photodissociation , photochemistry , methyl iodide , monomer , raman spectroscopy , excited state , ultraviolet , analytical chemistry (journal) , inorganic chemistry , polymer , organic chemistry , optics , physics , nuclear physics
The photodissociation of methyl iodide in various matrices at low temperature was studied. The observed Raman spectra excited by 514.5 nm laser radiation showed that there were two different photolytically produced iodine species isolated in the matrices after illumination by a medium pressure mercury lamp. One species which was dominant at lower iodine concentrations and exhibited a progression with an ωe of 201 cm −1 , belonged to the matrix isolated iodine monomer (I 2 ). The other species, which was dominant at higher iodine concentrations with an ω e of approximately 180 cm −1 , belonged to the iodine aggregate ((I 2 ) n ). Five progressions of resonance Raman or resonance fluorescence of these two species were also observed in the other matrices. The iodine aggregate in the methyl iodide matrix at 77 K was formed in a crystalline structure, while the photolytically generated iodine aggregate from CH 3 I/Ar (2/3) matrix at 10 K, after illumination with a mercury lamp, was in amorphous form. The rearrangement of photolytically produced iodine aggregate in methyl iodide matrix was observed as a function of the duration of illumination. Local heating effects of the laser radiation might induce the iodine monomer to aggregate in matrices. The photodissociation mechanism of methyl iodide in matrices is also proposed.