A velocity map imaging study of gold-rare gas complexes: Au-Ar, Au-Kr, and Au-Xe

摘要

The ultraviolet photodissociation dynamics of the gold-rare gas atom van der Waals complexes (Au-RG, RG=Ar, Kr, and Xe) have been studied by velocity map imaging. Photofragmentation of Au-Ar and Au-Kr at several wavelengths permits extrapolation to zero of the total kinetic energy release (TKER) spectra as monitored in the Au (P2 3/2 5 d10 6p) fragment channel, facilitating the determination of ground state dissociation energies of D_0″ (Au-Ar) =149±13 cm~(-1) and D0″ (Au-Kr) =240±19 cm~(-1), respectively. In the same spectral region, transitions to vibrational levels of an ′ =1/2 state of the Au-Xe complex result in predissociation to the lower Au (P2 1/2 5 d10 6p) +Xe (S1 0 5 p~6) fragment channel for which TKER extrapolation yields a value of D0″ (Au-Xe) =636±27 cm-1. Asymmetric line shapes for transitions to the v′ =14 level of this state indicate coupling to the Au (P2 3/2 5 d10 6p) +Xe (S1 0 5 p~6) continuum, which allows us to refine this value to D0″ (Au-Xe) =607±5 cm~(-1). The dissociation dynamics of this vibrational level have been studied at the level of individual isotopologues by fitting the observed excitation spectra to Fano profiles. These fits reveal a remarkable variation in the predissociation dynamics for different Au-Xe isotopologues. For Au-Ar and Au-Xe, the determined ground state dissociation energies are in good agreement with recent theoretical calculations; the agreement of the Au-Kr value with theory is less satisfactory.