Matrix-induced intersystem crossing in the photochemistry of the 1,2-dichloroethenes

Journal Article · Thu Mar 23 00:00:00 EST 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100343a026· OSTI ID:5111209

Laursen, S L; Pimentel, G C ^[1]

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1. Lawrence Berkeley Lab., CA (USA)

The photoproducts of the 1,2-dichloroethenes (DCE) in xenon matrix at 12 K differ from those observed in krypton matrix. In xenon, photolysis at 237 nm of both cis- and trans-dichloroethene results in elimination of both Cl{sub 2} and HCl as well as isomerization, whereas only HCl elimination and isomerization are observed in krypton. Longer wavelength irradiation has no effect on either DCE in Kr but produces small, distinct amounts of products in Xe. The results indicate that in xenon, chemistry is occurring through a triplet state as well as from the directly excited singlet state. Enhanced spin-orbit coupling in the heavy-atom environment facilitates intersystem crossing from the initial singlet to a triplet surface, as well as, no doubt, enhanced absorption directly into the triplet state. These effects provide access to the normally spin-forbidden chlorine elimination channel. The appearance of products in Xe at the lower photon energy is ascribed to direct T{sub 1} {l arrow} S{sub 0} absorption, assisted by the external heavy atom.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5111209
• Journal Information: Journal of Physical Chemistry; (USA), Vol. 93:6; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ETHYLENE
PHOTOCHEMICAL REACTIONS
ORGANIC CHLORINE COMPOUNDS
ABSORPTION SPECTROSCOPY
CHEMICAL REACTION YIELD
EXPERIMENTAL DATA
INFRARED SPECTRA
KRYPTON
MATRIX ISOLATION
PHOTOCHEMISTRY
PHOTOLYSIS
ULTRALOW TEMPERATURE
XENON
ALKENES
CHEMICAL REACTIONS
CHEMISTRY
DATA
DECOMPOSITION
ELEMENTS
FLUIDS
GASES
HYDROCARBONS
INFORMATION
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
RARE GASES
SPECTRA
SPECTROSCOPY
YIELDS
400500* - Photochemistry