Theory of Diatomic Photodissociation to Atomic Hyperfine Structure States

Abstract

AbstractWe present a general theory of the photodissociation of diatomic molecules to the hyperfine sublevels of open‐shell atomic fragments. The hyperfine interactions affect the fragment hyperfine sublevel populations, polarizations, etc., either when the fragment atomic hyperfine sublevels are optically resolved, when resonances possess hyperfine splittings, or both. The case of hyperfine splittings in resonances is of particular interest for states whose principle parentage is singlet, but which exhibit hyperfine splitting due to nonadiabatic mixing with close‐lying triplet states. Such resonances have been observed in the photodissociation of SiH+ (Sarre, P.J. et al., Phil. Trans. R. Soc. London, 1988, A324: 233). We also show how our nonadiabatic theory in the presence of hyperfine interactions reduces to the general theory of diatomic photodissociation to open‐shell atoms of Singer et al. (J. Chem. Phys., 1983, 79: 6060) when resonance hyperfine splittings or hyperfine structure states of the fragments are not resolved in particular experiments.