Large increases in the photoionization threshold energies of small Vx, NBx, and Fex clusters (x = 3-25) induced by chemisorption of H2 have been observed using photoionization time-of-flight mass spectrometry of a molecular beam. These shifts exhibit a definite dependence both on the number of atoms constituting the bare metal cluster and on the number of chemisorbed hydrogens, and are particularly large (≳ 0.8 eV) for multiple-H2 chemisorption on small clusters. A simple frontier orbital model for the chemisorption process predicts the direction of adsorbate-induced shifts in cluster ionization threshold for both H2 and NH3 as adsorbates.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry