Electron momentum spectroscopy studies on ring compounds. I. Benzene

Abstract

The complete valence shell electron separation energy spectra and momentum distributions are measured for benzene by electron momentum spectroscopy at a total energy of 1200 eV. The measured momentum distributions are compared with those calculated in the plane wave impulse approximation (PWIA) formalism using a (9s5p/4s1p) to (4s2p/2s1p) Gaussian basis set. The level of agreement between the measured momentum distributions and the PWIA-SCF orbital momentum distributions is, in general, surprisingly good, particularly given the restricted nature of the current SCF basis set. The inner valence 2e2g, 2e1u and 2a1g orbitals are severely split by final state correlation effects. The agreement between the measured and Green function many-body method calculated spectroscopic factors and separation energies is good, although the measured separation energy spectra contain significant strength up to 51 eV, this strength being mainly of 2e1u and 2a1g origin.