Quenching of Ar( 3P 1): rate constants for deactivation and “escape factors” for trapped radiation

Abstract

Fluorescence lifetimes in the presence of quencher were used to derive rate constants for quenching of Ar( 3P 1). The values obtained were: ▪ Possible mechanisms for quenching are considered in the light of the kinetic data. The quenching rate constants were combined with steady or pseudo-steady state intensity measurements (of the Stern—Volmer type) to yield effective rate constants for radiative decay. These latter rate constants are related to the “escape factors” for the imprisoned radiation. Escape factors for excitation by pulsed radiation were essentially identical when derived either directly from the lifetime studies or from the intensity measurements; they were also statistically indistinguishable from the escape factors for excitation by steady radiation. The similarity of the escape factors in the two cases confirmed our earlier conclusion that most of the detected fluorescence originates from that part of the system illuminated by the exciting radiation, even where there is very extensive radiation trapping.