Vibrational effects on valence electron momentum distributions of ethylene

Abstract

We report an electron momentum spectroscopy study of vibrational effects on the electron momentum distributions for the outer valence orbitals of ethylene (C(2)H(4)). The symmetric noncoplanar (e,2e) experiment has been conducted at an impact energy of 1.2 keV. Furthermore, a theoretical method of calculating electron momentum distributions for polyatomic molecules has been developed with vibrational effects being involved. It is shown from comparisons between experiment and theory that taking into account effects of the CH(2) asymmetric stretching and CH(2) rocking vibrational modes of C(2)H(4) is essential for a proper understanding of the electron momentum distribution of the 1b(3g) molecular orbital.