Accession Number : ADA130915

Title :   The Photodissociation of Nitromethane at 193 nm.

Descriptive Note : Technical rept.,


Personal Author(s) : Butler,L J ; Krajnovich,D ; Lee,Y T ; Ondrey,G ; Bersohn,R

PDF Url : ADA130915

Report Date : 28 Feb 1983

Pagination or Media Count : 65

Abstract : The dissociation of nitromethane following the excitation of the pi* yields pi transition at 193 nm has been investigated by two independent and complementary techniques, product mission spectroscopy. The primary process is shown to be cleavage of the C-N bond to yield CH3 and NO2 radicals. The translational energy distribution for this chemical process indicates that there are two distinct mechanisms by which CH3 and NO2 radicals are produced. The dominant mechanism releasing a relatively large fraction of the total available energy to translation probably gives NO2 radicals in a vibrationally excited 2B2 state. When dissociated, other nitroalkanes exhibit the same mission spectrum as CH3NO2, suggesting little transfer of energy from the excited NO2 group to the alkyl group during dissociation for the dominant mechanism. This conclusion is supported by the apparent dissociation to NO + O, which will occur for NO2 with 72 kcal/mole or more internal energy. Evidence is presented which suggests that the NO2 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. (Author)

Descriptors :   *Nitromethane, *Photodissociation, *Energetic properties, Fragmentation, Molecular beams, Molecular spectroscopy, Emission spectroscopy, Chemical reactions, Dynamics, Methyl radicals, Nitro radicals, Energy transfer, Energy levels

Subject Categories : Organic Chemistry
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE