A resonance Raman polarization study of the mode‐specific subpicosecond photodissociation of the NO₂ 2²B₂ state

Abstract

Abstract Vibronically specific subrotational period lifetimes of the predissociated 2 2 B 2 state of NO 2 vapour (250–235 nm) have been determined by spontaneous resonance Raman scattering polarization measurements. The lifetimes of the vibronic symmetric stretching, ν 1 ′, (100), bending, ν 2 ′, (101), and asymmetric stretching, ν 3 ′, (002), overtone levels are 75 ± 10 fs, 2.5 ± 05 ps and 155 ± 15 fs respectively. When one quantum of bending ( ν 2 ,′) is excited in combination with one quantum of totally symmetric stretching ( ν 1 ′), the lifetime increases from 75 ± 10 to 125 ± 15 fs (110). The 2 2 B 2 state electronic origin lifetime has been previously shown to be 42 ± 5 ps independent of angular momentum quantum numbers. These results are interpreted in terms of the shape of the potential energy surface intersections in the region and the results of earlier quantum yield measurements.