ELECTRON MOMENTUM SPECTROSCOPY STUDIES ON RING COMPOUNDS .1. BENZENE

The complete valence shell electron separation energy spectra and mome ntum distributions are measured for benzene by electron momentum spect roscopy at a total energy of 1200 eV. The measured momentum distributi ons are compared with those calculated in the plane wave impulse appro ximation (PWIA) formalism using a (9s5p/4s1p) --> [4s2p/2s1p] Gaussian basis set. The level of agreement between the measured momentum distr ibutions and the PWIA-SCF orbital momentum distributions is, in genera l, surprisingly good, particularly given the restricted nature of the current SCF basis set. The inner valence 2e2g, 2e1u and 2a1g orbitals are found to be severely split by final state correlation effects. The agreement between the measured and Green function many-body method ca lculated spectroscopic factors and separation energies is good, althou gh the measured separation energy spectra contain significant strength up to 51 eV, this strength being mainly of 2e1u and 2a1g origin.