Vibrationally resolved photoelectron imaging of gold hydride cluster anions: AuH- and Au2H-

Photoelectron spectra and angular distributions in photodetachment of gold hydride anions AuH- and Au2H- have been obtained using photoelectron velocity-map imaging. Both the images exhibit vibrationally resolved ground state transitions. The adiabatic electron affinities of AuH and Au2H 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) angstrom. The photoelectron images of Au2H- 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 Au2H, a new bent Au-Au-H structure with the angle of 131 degrees is suggested. Moreover, energy-dependent photoelectron anisotropy parameters are also reported and discussed. (C) 2010 American Institute of Physics. [doi:10.1063/1.3456373]