Monoenergetic unimolecular rate constants and their dependence on pressure and fluctuations in state-specific unimolecular rate constants

The Porter-Thomas distribution function P(k) is used to represent fluctuations in state-specific unimolecular rate constants for states that lie within a narrow energy interval E → E + dE. The sensitivity of concentration of reactant molecules versus time N(τ,E), the time-dependent rate constant k(τ,E), and the collision-averaged rate constant k(ω,E) to the width of P(k) is considered. The collision-averaged rate constant k(ω,E), found from an analysis of a Stern-Volmer plot, is found to be rather insensitive to P(k).