Effects of Hyperfine Interaction in Atomic Photoionization

The chapter is devoted to theoretical consideration of the role of hyperfine interaction in atomic photoionization. The interaction between nuclear spin and an atomic shell considered to give a small correction in a variety of phenomena may have significant effects on polarization and correlation parameters of a process. We outline a theoretical approach based on statistical tensors and density matrices for determination of photoelectron angular distribution in two-colour atomic ionization accounting for their evolution caused by nuclear spin. As a practical example we consider double resonant ionization of Xe through excitation via discrete and Rydberg autoionizing states, as in the first isotope-selective experiment in VUV domain (O’Keeffe et al in Phys Rev Lett 111:243002(1)–243002(5), 2013 [44]). Variations in the angular pattern for the different isotopes and light polarization are shown. The possibility to determine the hyperfine constant is discussed.