Selective vibrational excitation of the ethylene--fluorine reaction in a nitrogen matrix. II
The product branching between 1,2-difluoroethane and vinyl fluoride (plus HF) of the selective vibrationally stimulated reaction of molecular fluorine with C/sub 2/H/sub 4/ has been studied in a nitrogen matrix at 12 K and found to be the same for five different vibrational transitions of C/sub 2/H/sub 4/ between 1896 and 4209 cm/sup -1/. The HF/DF branching ratio of the reaction of F/sub 2/ with CH/sub 2/CD/sub 2/, trans-CHDCHD, and cis-CHDCHD was determined to be 1.1, independent of precursor C/sub 2/H/sub 2/D/sub 2/ isomer and particular mode which excited the reaction. These results, as well as the analysis of the mixtures of partially deuterated vinyl fluoride molecules produced by each C/sub 2/H/sub 2/D/sub 2/ isomer indicate that the product branching occurs by ..cap alpha beta.. elimination of HF(DF) from a vibrationally excited, electronic ground state 1,2-difluoroethane intermediate. Selective vibrational excitation of fluorine reactions in isotopically mixed matrices t-CHDCHD/C/sub 2/H/sub 4//F/sub 2//N/sub 2/ and CH/sub 2/CD/sub 2//C/sub 2/H/sub 4//F/sub 2//N/sub 2/, and in matrices C/sub 2/H/sub 2//C/sub 2/H/sub 4//F/sub 2//N/sub 2/ revealed a high degree of isotopic and molecular selectivity. The extent to which intermolecular energy transfer occurred is qualitatively explained in terms of dipole coupled vibrational energy transfer. A study of the loss of absorbance of the C/sub 2/H/sub 4/ x F/sub 2/ pairs in case of ..nu../sub 9/ as a function of both the laser irradiation frequency within the absorption profile, and the ethylene concentration showed that the C/sub 2/H/sub 4/ x F/sub 2/ absorption is inhomogeneously broadened. Substantial depletion of reactive pairs which did not absorb laser light is interpreted in terms of Forster transfer.
- Research Organization:
- Laboratory of Chemical Biodynamics, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
- OSTI ID:
- 6131349
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 79:2; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ALKENES
BRANCHING RATIO
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY LEVELS
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
ETHYLENE
EXCITATION
EXCITED STATES
FLUORINE
HALOGENS
HYDROCARBONS
INFRARED RADIATION
KINETICS
LASER RADIATION
NONMETALS
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
RADIATIONS
REACTION KINETICS
ULTRALOW TEMPERATURE
VIBRATIONAL STATES