Absorption spectra of contact-charge-transfer bans and photochemical reactions of simple alkenes in the cryogenic oxygen matrix
The UV-vis absorption spectra and photochemistry of alkene-oxygen pairs in solid oxygen at 10 K have been studied. The contact-charge-transfer (CCT) bands well separated from the intrinsic absorption bands of isolated alkenes were recorded with the maxima at 218, 243, 234, 235, 263, and 287 nm for propene, 2-methylpropene (MP), cis-2-butene (CB), trans-2-butene (TB), 2-methyl-2-butene (MB), and 2,3-dimethyl-2-butene (DMB), respectively. The vertical transition energy correlated linearly with the ionization potential of the alkenes. Photochemical reaction products in the excitation within the CCT bands were studied by using FTIR. The reaction in the ion pair state can be classified into the following four pathways: (i) photooxygenation to given an oxygen adduct, which is observed only for DMB; (ii) cis-trans isomerization, which is the major reaction path for CB and TB, suggesting the crossing to the alkene triplet state; (iii) double-bond scission to give two corresponding carbonyl compounds, which is observed for all alkenes studied with energy threshold higher than the photooxygenation and cis-trans isomerization; (iv) formation of CO/sub 2/, CO, and O/sub 3/ which occurs at still shorter wavelength than the double-bond scission. In the case of ethene and propene, HO/sub 2/ was also produced. Relevance of the present results to those in the CCT photochemistry in the oxygen-saturated organic liquid and on the semiconductor surfaces has been discussed.
- Research Organization:
- National Institute for Environmental Studies, Ibaraki, Japan
- OSTI ID:
- 6807395
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 91:6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
BUTENES
PHOTOCHEMICAL REACTIONS
OXYGEN
PROPYLENE
ABSORPTION SPECTROSCOPY
ALKENES
EXPERIMENTAL DATA
INFRARED SPECTRA
IONIZATION POTENTIAL
MATRIX ISOLATION
PHOTOCHEMISTRY
ULTRALOW TEMPERATURE
ULTRAVIOLET SPECTRA
VISIBLE SPECTRA
CHEMICAL REACTIONS
CHEMISTRY
DATA
ELEMENTS
HYDROCARBONS
INFORMATION
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
SPECTRA
SPECTROSCOPY
400500* - Photochemistry
500100 - Environment
Atmospheric- Basic Studies- (-1989)