Large isotope effects in photodissociation of polyatomic molecules

Abstract
The example of the photodissociation of HCN is used to demonstrate the existence of huge isotope effects in general classes of the photodissociation of polyatomic molecules. The isotopic ratio of photodissociation rates is of the form exp[(μ11/2−μ21/2) K], where μ1 and μ2 are the reduced masses of the atomic fragments (different isotopes), and where K is dependent on molecule and fragment normal modes as well as upon the interfragment repulsive potential. Conditions for the maximization of K are discussed.