Singlet-oxygen-sensitized delayed fluorescence of phthalocyanines caused by photosensitized and direct excitation of dissolved oxygen by laser radiation

Abstract

This paper provides a brief account of the prior studies of singlet-oxygen-sensitized delayed fluorescence (SOSDF) of phthalocyanines and related compounds caused by photosensitized singlet oxygen generation in dye solutions, and presents new results, which unambiguously demonstrate that SOSDF also appears in phthalocyanine solutions upon direct excitation of dissolved oxygen by 1270 nm laser radiation. In all cases, light emission was shown to appear owing to the unique property of phthalocyanine molecules to efficiently accumulate energy of two molecules of singlet oxygen. Dependences of the IR-excited SOSDF on the phthalocyanine concentration, laser power and addition of singlet oxygen quenchers have been studied and kinetic equations are proposed for analyses of these data.