Singlet Oxygen in a Cell: Spatially Dependent Lifetimes and Quenching Rate Constants

Singlet molecular oxygen, O(2)(a(1)Delta(g)), can be created in a single cell from ground-state oxygen, O(2)(X(3)Sigma(g)(-)), upon focused laser irradiation of an intracellular sensitizer. This cytotoxic species can subsequently be detected by its 1270 nm phosphorescence (a(1)Delta(g) --> X(3)Sigma(g)(-)) with subcellular spatial resolution. The singlet oxygen lifetime determines its diffusion distance and hence the intracellular volume element...