Measurements of molecular fragment alignment and orientation in the UV photodissociation of NO2 and O3

Abstract

REMPI-TOF studies of the UV photodissociation of NO2 and O3 at 320 nm and 270 nm respectively have allowed both the orientation and alignment parameters of the molecular photofragments to be determined. The orientation parameter, β20(21), for the NO(X2Π, v = 0) fragment is found to be essentially the same for the three quantum states, N = 29, 30 and 40 with a value of 0.24 ± 0.04 (2σ), as probed via (1 + 1′) REMPI, on the A2Σ+ (v = 0) ← X2ΠΩ (v = 0) transition.The O2 (a 1Δgv = 0 J = 20) fragment shows a markedly larger orientation parameter, for example β20(21) = 0.55 ± 0.04, measured on the S(20) transition. These orientation parameters and the accompanying alignment parameters which describe the fragments' angular momentum polarisation have been used to confirm spectral assignments within the highly perturbed (2 + 1) d 1Πg(v = 2) ←← a 1Δg (v = 0) REMPI spectrum of O2.