IKER LEON, ZHENG YANG AND LAI-SHENG WANG, DEPARTMENT OF CHEMISTRY, BROWN UNIVERSITY, PROVIDENCE, RI 02912, USA.
We report high resolution photoelectron spectra of Au2- and Au4- obtained with a newly-built photoelectron imaging apparatus. Gold anions are produced by laser vaporization and the desired specie is mass selected and focused into the collinear velocity-map imaging (VMI) lens assembly. The design of the imaging lens has allowed us to obtain less than 0.9% energy resolution for high kinetic energy electrons ( \textgreater 1eV) while maintaining wavenumber resolution for low kinetic energy electrons. Although gold dimer and tetramer have been studied in the past, we present spectroscopic results under high resolution. For Au2-, we report high resolution spectra with an accurate determination of the electron affinity together with a complete vibrational assignment, for both the anion and neutral ground states, while for Au4-, we are able to resolve a low frequency mode and obtain accurately the adiabatic detachment energy.