Femtosecond Time-Resolved Absorption of Oxyhaemoglobin Photolysis in Living Erythrocytes

By using the pump--probe technique, the femtosecond (fs) time-resolved absorption dynamics of oxyhaemoglobin (oxy Hb) in living erythrocytes was studied for the first time to our knowledge. The changing course of erythrocyte absorption at 400nm was found to be composed of three exponential decay components with the time constants of 200±28fs, 3.60±0.14ps and 215±21ps respectively, which are consistent with those of oxy Hb water solution measured in the same way, indicating that the fast process (less than 1ns) of photo-induced response in erythrocytes was as the same as that in oxy Hb aqueous solution. These three decay components were assigned to the transitions from excited states of unligated haemoglobin (Hb_I^*, Hb_II^*) and fast geminate recombination of O₂ and Hb, respectively.