Photodissociation dynamics of ICN. Unequal population of the CN X2Σ+ fine-structure components

Abstract

Photolysis of ICN at 281.5, 266 and 249 nm produces CN X²Σ⁺ fragments in which the population of the F₁(J″=N″+½) and F₂(J″=N″–½) fine-structure components vary markedly as a function of v″, N″ and dissociation wavelength. Population differences favour either F₁ or F₂, and can be > 2:1. A model is proposed to explain this behaviour, in which out-of-plane, spin-dependent forces cause the electron spin on CN to have a preferred orientation with respect to rotation of the CN fragment. The strong N″ dependence of the F₁/F₂ ratio is attributed to interference between different dissociation channels, probably enhanced by various curve crossings.