Short Pulse Absorption Spectroscopy of Nitromethane Photolysis

Abstract

We are applying short pulse techniques to studies of small molecular fragments, stable or reactive radical species emergent as the primary products of unimolecular decomposition of simple photolabile materials. Nitro-methane (CH₃NO₂) photolysis has been the subject of extensive prior investigations under varying conditions of irradiation wavelength, phase, temperature, and with active additives. The identity of the primary products and the kinetics of the reaction remain unresolved, although several mechanisms have been advanced to explain the observed products. From nitromethane vapor the list of major final products which have been reported [1] includes CH₃ONO, CH₂O, CH₃NO, NO, and N₂O; minor final products include H₂, CH₄, N₂, and CO; and a number of reaction intermediates have been reported, notably NO₂ and HNO. As an inferred early product, NO₂ was estimated to have a quantum yield as large as 0.6, and this fragment has been our principal object of study to date.

Research supported by the Office of Naval Research.