PHOTOIONIZATION SPECTROSCOPY OF YTTRIUM CLUSTERS - IONIZATION-POTENTIALS FOR Y-N AND YNO (N=2-31)

The photoionization spectra of yttrium clusters Yn, and their monoxides YnO have been recorded for n=2-31. As has been observed for other transition metal clusters, the vertical ionization potentials decrease rapidly yet nonmonotonically to ∼10 atoms, beyond which a more gradual decrease takes place. The ionization potentials of the cluster monoxides were found to be similar to those of the corresponding bare clusters except for n≤10 where differences of 0.1-0.3 eV were observed in some cases. The absence of magic numbers or odd-even alternations is taken as evidence that threshold photoionization occurs from a localized 4d orbital rather than a delocalized band derived from 5s valence electrons. © 1995 American Institute of Physics.