Fluorescence decay of aromatic vapours. III. Single vibronic lifetimes and collision cross-sections for pyrimidine

Abstract

In this paper the results of a lifetime study of the ¹B₁ state of pyrimidine vapour in the pressure range 1.2-60 Pa are presented. These lifetimes show an extraordinary pressure dependence, with collision cross-sections of 30-40 times hard sphere. It is shown that pyrimidine behaves as a small molecule. The collision-induced decay process is intersystem crossing and it is the most effective collision-induced process yet reported for the small-molecule limit.