Photofragment vibrational, rotational, and translational distributions for N2–HF (v=1)

Abstract

Two new methods have been developed for studying the vibrational predissociation dynamics of weakly bound complexes at the state-to-state level. The first is based upon the use of two F-center lasers, one to photodissociate the complex by single quantum state excitation and the second to probe the final states of the resulting fragments. These pump–probe experiments are carried out with angular resolution of the photofragments, giving information on the associated vibrational, rotational and translational distributions. The second method makes use of a dc electric field to orient the parent molecules prior to photodissociation. In this way the two fragments recoil to different sides of the apparatus, allowing us to detect them independently. These experiments also provide us with valuable information on the nature of the photofragment angular distribution in the molecule fixed frame. The present application is to the study of the vibrational predissociation dynamics of N2–HF (v=1). A combination of the two methods has enabled us to determine that the complex dissociates via two distinctly different channels with similar probability, namely one that produces vN2= 1, jHF=7 and the other vN2= 0, jHF=12. The rotational distribution of the N2 fragment is also determined by fitting the angular distributions. Conservation of energy is used to determine the dissociation energy of the complex (D0) to be 398±2 cm−1.