VALENCE-SHELL ELECTRON MOMENTUM DISTRIBUTIONS OF CYCLOPROPANE BY SYMMETRICAL NONCOPLANAR (E, 2E) SPECTROSCOPY

Recently, we reported an investigation on the electronic structure of the valence-shell of cyclopropane and presented the angular dependent ionization energy spectrum measured by (e, 2e) spectroscopy. In this work, direct measurements of electron momentum distributions corresponding to individual ionic states of the valence-shell of cyclopropane were made. It was found that the experimental momentum distributions were in general accord with the theoretical momentum distributions generated using standard Gaussian basis sets. However, some small discrepancies could be noted, for instance in the 3e' and 2e' orbitals, which generally reflected the need for more sophisticated basis sets and/or the inclusion of configuration interactions for precise wave-function modelling of the valence region. An R-factor analysis similar to that commonly employed in LEED analysis was introduced for (e, 2e) data as a means of comparing similar data and for normalization purposes. The normalization constants so obtained were used to calculate the experimental spectroscopic pole-strengths. Good agreement was found between the experiment and the Green's function calculations for the two inner valence ((2e')-1 and (2a1)-1) states. As well, the similarities in the chemical bonding properties of cyclopropane and other olefins were discussed.