Molecular Photoelectron Angular Distributions

Molecules present different challenges than do atoms when attempting to describe photoelectron angular distributions. The noncentral nature of the molecular potential influences the departing photoelectron so that the resulting angular distribution may depend on the portion of the molecular potential the photoelectron samples as it departs. In addition, the molecule may be vibrating and rotating so that the molecular potential is varying in space and time. The bonds between the constituent atoms in the molecule may be flexing, and the angles between the atoms may be changing during the pd process. Indeed, the molecule itself may not survive the pd process. In this chapter, the forms of the photoelectron angular distributions for randomly oriented molecules and fixed-in-space molecules are derived. It is seen that the photoelectron angular distribution of fixed-in-space molecules shows the presence of odd harmonics which are not present in the differential cross-section for randomly oriented molecules. The form of the photoelectron angular distribution for some important special cases is derived in in-chapter examples. End-of-chapter problems are included to reinforce introduced concepts and to give readers a chance to practice the relevant mathematics.