Abstract
Relative partial photoionization cross sections have been measured for the valence bands of [(η-C
6H
6)
2Cr] and [(η-C
6H
5Me)
2Mo] over the photon energy ranges 24–80 eV ([(η-C
6H
6)
2Cr]) and 24–100 eV ([(η-C
6H
5Me)
2Mo]). Both compounds show pronounced intensity increases of the metal-based ionizations (a
−1
1g and e
−1
2g) in the region of the
np subshell ionization potentials, attribute to
nd resonant photoemission following
np→
nd giant resonant absorption. Shape resonances are also observed in the cross sections of these bands. For [(η-C
6H
5Me)
2Mo], the two resonance processes are almost coincident in photon energy, but can be distinguished more clearly in the [(η-C
6H
6)
2Cr] cross sections. Evidence for metal d—carbon 2pπ covalency in the e
1g set of molecular orbitals is found, with features in the cross sections of the metal-based bands correlating with those in the e
−1
1g ionizations. The e
−1
1u bands show an essentially monotonic cross section decrease with photon energy.