Dynamics of photofragmentation of dimethylnitrosamine from its first two excited singlet states

R. Lavi, S. Rosenwaks

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12 Scopus citations


The photofragmentation of dimethylintrosamine (DMN) from its first two excited singlet states was studied by monitoring the scalar and vector properties of the nascent NO via one-photon laser induced fluorescence, combined with polarization and sub-Doppler spectroscopy. The DMN was fragmented following irradiation at 363.5 nm [S1←S0(π*←n)] and 250 nm [S2←S0(π*←π)]. The photofragmentation is characteristic of a direct dissociation mechanism on a repulsive potential surface for both dissociation wavelengths. The NO fragment ejects with its velocity along the bond that breaks, and its angular momentum vector tends to be perpendicular to the plane of the C2NNO frame of the parent molecule. The experiments corroborate that the transition dipole moment is perpendicular to the plane of the parent molecule for the S1←S0 transition and lies parallel to this plane, along the bond which breaks, for the S 2←S0 transition. The Λ-doublet population ratio obtained for the two dissociation wavelengths is consistent with an A″ symmetry for the S1 and an A′ symmetry for the S 2 state. Finally, a comparison between the photodissociation of tert-butyl nitrite (TBN) and DMN is presented. In particular, it is shown that in both molecules, for both states, the fragmentation is largely planar with the main forces acting approximately along the bond which breaks. On the other hand, retainment of vibrational energy in the NO fragment is observed only for TBN S1. Also, a preference of the antisymmetric Λ component in NO from TBN S2 and of the symmetric component in DMN S2 is found.

Original languageEnglish
Pages (from-to)1416-1426
Number of pages11
JournalJournal of Chemical Physics
Issue number3
StatePublished - 1 Jan 1988

ASJC Scopus subject areas

  • General Physics and Astronomy
  • Physical and Theoretical Chemistry


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