PHOTODISSOCIATION OF JET-COOLED METHYL AND T-BUTYL NITRITE NEAR 380 NM

A one-colour photolysis-ionisation study of the photodissociation of methyl and t-butyl nitrite near 380 nm in a supersonic jet has been performed. The NO photoproduct has been characterised by state-resolved probing by (2 + 1 ) REMPI via the C <-- X-delta bands of NO. The photodissociation of methyl nitrite yields predominantly vibrationally cold NO, while t-butyl nitrite photodissociation shows a propensity for formation of NO in the first excited vibrational level. The NO fragments are rotationally highly excited in both cases, and the rotational population distributions can be fitted by Gaussian curves in agreement with recent dynamical calculations. The different vibrational energy disposal is attributed to the different excitation of a rapidly predissociating complex. Previous results that were at variance with knowledge of the dynamics of the predissociation of alkyl nitrites may have been affected by experimental problems.