A time-resolved study of singlet molecular oxygen (1.DELTA.gO2) formation in a solution-phase photosensitized reaction: a new experimental technique to examine the dynamics of quenching by oxygen

The solution-phase, time-resolved phosphorescence of singlet molecular oxygen (/sup 1/..delta../sub g/O/sub 2/), created by energy transfer from a sensitizer, has been examined by using a near-infrared detection system capable of resolving events that result in the formation of /sup 1/..delta../sub g/O/sub 2/. As a method by which to examine oxygen quenching reactions, this approach is seen to complement flash absorption studies. Unlike existing experimental techniques, however, their approach is uniquely sensitive to rate-limiting steps that might exist during the energy-transfer process to form /sup 1/..delta../sub g/O/sub 2/. In this report, they present oxygen quenching rate constants for the triplet state of five different molecules in several solvents. In addition, they suggest that a static quenching component may be involved in the oxygen-induced deactivation of a triplet state.