Figure . Bleaching of 9,10-dimethylanthracene upon reaction with 1 O2 photosensitized by M[Me-AHP] (M = Mn, Pd, Pt) and the standard -methylene blue. Note that the absorbance at 358 nm represents the combined absorbance of 9,10-dimethylanthracene and the photosensitizer that does not bleach (see Figures ). All the compounds showed identical absorbance at irradiation wavelength (580 nm). light results in distinct absorption changes (Figure ). These characteristic changes correspond to bleaching of the ground state spectrum (Figure ) upon population of the triplet state.