An investigation of the triplet state of pheophorbide a using laser flash photolysis

The triplet properties of pheophorbide a (PPa) have been investigated in benzene using nanosecond laser flash photolysis. The absorption maximum at 460 nm, which decays with a lifetime of 9.1 mu s, has been assigned to the triplet¯triplet (T¯T) absorption of PPa. The extinction coefficient of this absorption is 75,900 dm3 mol-1 cm-1 and the triplet quantum yield is 0.65±0.03 (versus benzophenone).