Spectroscopy of transition metal clusters: Correlation of electronic structure to reactivity
Conceicao, Jose J. B.
Smalley, Richard E.
Doctor of Philosophy
Photoelectron spectra of negatively charged iron, cobalt and nickel clusters in the size range of 5 to 20 (4 to 26) and 5 to 20 atoms respectively have been obtained. The electron affinity (E.A.) values along with the reported ionization potential (I.P.) have been used as a probe of the valence electronic structure of these clusters. This information is further used to understand the reactivity of the neutrally charged counterpart clusters of iron, cobalt and nickel with dihydrogen. An excellent anticorrelation between an empirically determined quantity called Ep, defined as IP $-$ EA $-$ e$\sp2$/r, and the reactivity of these clusters is observed. Ep is a direct measure of the polarizability of the clusters; The excellent anticorrelation is consistent with the Pauli Repulsion mechanism and is found to be a significant factor in controlling the reactivity of these clusters.