Photoelectron spectroscopic studies of polyatomic molecules. I. Theory

Abstract

A theory for photoionisation in polyatomic molecules has been developed. Expressions for angular distribution of electrons ejected from these targets with either fixed or random orientation in space are derived. The results obtained can therefore be used to study photoionisation of polyatomic molecules in either the gaseous phase or oriented on liquid and solid surfaces. The transformation properties of the point symmetry group of the molecule are fully taken into account to reduce the expressions to their simplest possible forms. The analysis is general in that it is independent of any particular model for the description of the dynamics of photoionisation and can be used to derive expressions for either completely unpolarised, partially or linearly polarised beams of incident radiation.