ZEKE spectroscopy of free transition metal clusters

Transition metal clusters are produced in molecular beams with laser vapori zation of metal targets. Vibrationally and rotationally resolved electronic spectra of the metal clusters are obtained with zero electron kinetic ener gy (ZEKE) photoelectron spectroscopy. The resolution of the spectra is of t he order of sub-millielectron volts. Experiments on bare vanadium and yttri um clusters and ligated yttrium, zirconium, and niobium clusters are presen ted. The bond length of vanadium dimer is determined from the rotationally resolved spectra. Electronic states and molecular geometries of larger clus ters are determined by combining the vibrationally resolved spectra with de nsity functional theory and Franck-Condon factor calculations. (C) 2000 Els evier Science B.V. All rights reserved.