Angular distribution of the photoelectron spectra for ethylene, propylene, butene and butadiene

• Published in: Journal of electron spectroscopy and related phenomena 1974, Vol.3 (1), p.59-70
• Main Authors: White, R.M., Carlson, T.A., Spears, D.P.
• Format: Article
• Language: English
• ISSN: 0368-2048; 1873-2526
• DOI: 10.1016/0368-2048(74)80075-7

The photoelectron spectra using the He I resonance line (21.22 eV) were measured for ethylene, propylene, 1-butene, cis-butene, trans-butene and 1,3-butadiene as a function of angle between the direction of the incoming photons and outgoing photoelectrons. From these data the angular parameter, β, is obtained for each photoelectron peak in each spectrum. The β value is a function of the energy of the photoelectron and the nature of the molecular orbital from which the photoelectron is ejected. A qualitative comparison is made between the experimentally derived β values and the molecular orbital assignments. In particular, it is noted that the photoelectron peak corresponding to the CC double bond π orbital yields a relatively high value of β. This has led in the case of butadiene to a confirmation that the first two photoelectron peaks both result from ionization in π orbitals.