Reactive and inelastic processes involving I/sub 2/(D /sup 1/. sigma. /sup +//sub u/) with the collision partners CH/sub 4/, CH/sub 3/Cl, CF/sub 3/Cl, and CF/sub 4/

Journal Article · Tue Mar 15 04:00:00 EST 1983 · J. Chem. Phys.; (United States)

OSTI ID:5469605

Donovan, R J; O'Grady, B V; Lain, L; Fotakis, C

Fluorescence from the D /sup 1/..sigma../sup +//sub u/ state of I/sub 2/, and from other ion-pair states populated as a result of inelastic collisions with the molecules CH/sub 4/, CH/sub 3/Cl, CF/sub 3/Cl, and CF/sub 4/, was studied throughout the 200--510 nm region. I/sub 2/(D /sup 1/..sigma../sup +//sub u/) was optically pumped using an ArF laser (lambda = 193 nm) and the above spectral region recorded with single laser shots by employing an optical multichannel analyzer. The physical quenching of I/sub 2/(D /sup 1/..sigma../sup +//sub u/) was found to involve an electronic cascade, through intermediate states, terminating in the lowest ion-pair state I/sub 2/(/sup 3/Pi/sub 2g/). The presence of reactive channels was identified by the reduction in I/sub 2/ fluorescence following successive laser shots. Fluorescence from I/sub 2/(D /sup 1/..sigma../sup +//sub u/) was also studied following excitation with a cw mercury lamp (lambda = 185 nm) and Stern--Volmer analysis of these data yielded total removal rate constants (reactive+inelastic channels), viz; k(CH/sub 4/) = (7.9 +- 0.3) x 10/sup -10/, k(CH/sub 3/Cl) = (21.0 +- 1.0) x 10/sup -10/, k(CF/sub 3/Cl) = (7.1 +- 0.4) x 10/sup -10/, k(CF/sub 4/) = (6.0 +- 1.0) x 10/sup -10/ (all in cm/sup 3/ molecule/sup -1/ s/sup -1/ units). The presence of reactive channels was confirmed using end-product analysis techniques and it was shown that the lowest ion-pair state I/sub 2/(/sup 3/Pi/sub 2g/) also reacts with CH/sub 4/ and possibly with CF/sub 3/Cl.

• Research Organization: Department of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ Scotland, United Kingdom
• OSTI ID: 5469605
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 78:6; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ALKANES
CARBON TETRAFLUORIDE
CHLORINATED ALIPHATIC HYDROCARBONS
COLLISIONS
ELEMENTS
EMISSION SPECTRA
FLUORESCENCE
FLUORINATED ALIPHATIC HYDROCARBONS
HALOGENATED ALIPHATIC HYDROCARBONS
HALOGENS
HYDROCARBONS
IODINE
LUMINESCENCE
METHANE
METHYL CHLORIDE
MOLECULE COLLISIONS
MOLECULE-MOLECULE COLLISIONS
NONMETALS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
SPECTRA