Photodissociation of nitromethane at 193 nm
The dissociation of nitromethane following the excitation of the ..pi..* reverse arrow ..pi.. transition at 193 nm has been investigated by two independent and complementary techniques, product emission spectroscopy and molecular beam photofragment translational energy spectroscopy. The primary process is shown to be cleavage of the C--N bond to yield CH/sub 3/ and NO/sub 2/ radicals. The translational energy distribution for this chemical process indicates that there are two distinct mechanisms by which CH/sub 3/ and NO/sub 2/ radicals are produced. The dominant mechanism releasing a relatively large fraction of the total available energy to translation probably gives NO/sub 2/ radicals in a vibrationally excited /sup 2/B/sub 2/ state. When dissociated, other nitroalkanes exhibit the same emission spectrum as CH/sub 3/NO/sub 2/, suggesting little transfer of energy from the excited NO/sub 2/ group to the alkyl group during dissociation for the dominant mechanism. This conclusion is supported by the apparent loss of the slow NO/sub 2/ product in the molecular beam studies to unimolecular dissociation to NO+O, which will occur for NO/sub 2/ with 72 kcal/mol or more internal energy. Evidence is presented which suggests that the NO/sub 2/ produced via the minor mechanism, which releases a smaller fraction of the available energy to translation, has a large cross section for absorbing an additional photon via a parallel transition and dissociating to NO+O.
- Research Organization:
- Materials and Molecular Research Division, Lawrence Berkeley Laboratory and Department of Chemistry, University of California, Berkeley, California 94720
- OSTI ID:
- 5960250
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 79:4
- Country of Publication:
- United States
- Language:
- English
Similar Records
Multiple product pathways in photodissociation of nitromethane at 213 nm
Evidence for stepwise dissociation dynamics in acetone at 248 and 193 nm
Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
NITROMETHANE
PHOTOLYSIS
EMISSION SPECTRA
ULTRAVIOLET RADIATION
CHEMICAL EXPLOSIVES
CHEMICAL REACTIONS
DECOMPOSITION
ELECTROMAGNETIC RADIATION
EXPLOSIVES
NITRO COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
RADIATIONS
SPECTRA
400500* - Photochemistry