Vibrationally resolved photoelectron imaging of gold hydride cluster anions: AuH- and Au_2 H-

摘要

Photoelectron spectra and angular distributions in photodetachment of gold hydride anions AuH- and Au_2 H- have been obtained using photoelectron velocity-map imaging. Both the images exhibit vibrationally resolved ground state transitions. The adiabatic electron affinities of AuH and Au_2 H are measured to be 0.758(20) and 3.437(3) eV, respectively. Franck-Condon analyses of the AuH spectra determined that the equilibrium bond length of the ground state of AuH- is 1.597 (6) ?. The photoelectron images of Au_2 H- show a vibrational progression of 148 (4) cm~(-1) assigned to the Au-Au stretching mode at the ground state. Ab initio calculation results are in excellent agreement with the experimental results. For the ground state of Au_2 H, a new bent Au-Au-H structure with the angle of 131° is suggested. Moreover, energy-dependent photoelectron anisotropy parameters are also reported and discussed.