title: Fine- and hyperfine-structure effects in molecular photoionization. I. General theory and direct photoionization.
abstract: We develop a model for predicting fine- and hyperfine intensities in the direct photoionization of molecules based on the separability of electron and nuclear spin states from vibrational-electronic states. Using spherical tensor algebra, we derive highly symmetrized forms of the squared photoionization dipole matrix elements from which we derive the salient selection and propensity rules for fine- and hyperfine resolved photoionizing transitions. Our theoretical results are validated by the analysis of the fine-structure resolved photoelectron spectrum of O2 reported by Palm and Merkt [Phys. Rev. Lett. 81, 1385 (1998)] and are used for predicting hyperfine populations of molecular ions produced by photoionization.
authors.affiliation: Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Germann
authors.affiliation: Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Willitsch