Experimental and theoretical studies on laser photolysis kinetics of purple membrane

Purple membrane suspension prepared from strain RiMi of Halobacterium halobium is excited by a doubled frequency Q-switched Nd:YAG laser with 10ns pulse duration and 10Hz repetitive rate. A He-Ne laser and an Ar+ laser are respectively used as a probing beam. The sample's response signal is detected by an avalanche photodiode and measured by a 300MHz digitizing oscilloscope. The laser photolysis kinetics of the purple membrane is theoretically analyzed and some important equations are derived. The experimental curves are fitted by the nonlinear least square method according to the theoretical model. The kinetic parameters of the purple membrane photocycle such as decay time constants, absorption cross sections are calculated out and discussed.