A study of valence level photoelectron cross sections for the metallocenes of vanadium, chromium, cobalt and nickel from 20 to 100 eV

Abstract

Relative partial photoionization cross sections and photoelectron branching ratios have been measured for the valence bands of the bis-η 5-cyclopentadienyl compounds of vanadium, chromium, cobalt and nickel over the photon energy range 20 to 80 or 100 eV. The d bands show cross section features attributable to 3d resonant photoemission in the vicinity of the 3p → 3d giant resonance absorption. These features are stronger for V and Cr than for Co and Ni. Other intensity maxima are attributed to shape resonances in f ionization channels for the a 1′ and e 2′ ionizations those for the a 1′ being stronger than those for the e 2′ bands. The 2 e 1″ bands of Co(η-C 5H 5) 2 and Ni(η-C 5H 5) 2 show particularly strong shape resonances. Evidence is presented for d orbitals covalency in the 1 e 1″ orbitals. Previous assignments for the a 1′ ionizations are confirmed.