Two-photon photodissociation of jet-cooled NO2 near 450 nm. Rotational distributions of NO

Abstract

The two-photon photodissociation of expansion-cooled NO2 has been studied using dissociation and simultaneous two-photon l.i.f probing of the nascent NO(X) by a single scanning dye laser in the 428, 450 and 475 nm wavelength range corresponding to the γ(2, 1)γ(1, 0)γ(0, 0) and γ(0, 1) two-photon bands of NO. While the nascent NO formed in the 450 nm region exhibits a Boltzmann-like rotational population distribution, a distinct bimodal distribution is observed in the 475 nm region. Attention is drawn to the possibility that these differences reflect different branching ratios between the O(3P) and O(1D) dissociation channels and that the branching ratio varies with wavelength and the nature of the intermediate state involved at the one-photon level.