Photophysical processes in the vapour-phase measured by the optic-acoustic effect. Part 1.—The model and apparatus for the study of radiationless processes

Abstract

The use of the optic-acoustic effect in the study of radiationless processes from excited electronic states is discussed. A multi-state relaxation model is developed, and it is shown in some detail for a system of simple photophysical processes which are typical of those observed for aromatic molecules. The apparatus, involving the use of a capacitance microphone, is described, and the response of the microphone, as a function of both modulation frequency and gas pressure, is theoretically and experimentally determined.