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

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(²P_3/2^°[5d¹⁰6p]) fragment channel, facilitating the determination of ground state dissociation energies of D₀^″(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 Ω^′=1/2 state of the Au–Xe complex result in predissociation to the lower Au(²P_1/2^°[5d¹⁰6p])+Xe(¹S₀[5p⁶]) 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(²P_3/2^°[5d¹⁰6p])+Xe(¹S₀[5p⁶]) 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. [ABSTRACT FROM AUTHOR]