dependence of the intramolecular hydrogenabstraction reaction of n-alkyl anthraquinone-2-carboxylates (AQ-n, n=2–20) has been studied by steady-state photolysis, phosphorescence, laser flash photolysis, and two-step laser induced fluorescence spectroscopies. All the results indicate that the excited triplet of the anthraquinone chromophore abstracts a hydrogen atom from its methylene side chain, whose rate