Laser Flash Experiments Research Articles

SIMULATION ANALYSIS OF THE PHOTOCONVERSION PROCESS OF SQUID RHODOPSIN AT LIQUID HELIUM TEMPERATURE

Abstract—The photoconversion process among squid rhodopsin, bathorhodopsin isorhodopsin and hypsorhodopsin was studied at liquid helium temperature. We evaluated the relative quantum yields of the photoconversion among four pigments by analysing the time‐dependent change of absorption spectra. The result suggests that hypsorhodopsin is the common intermediate of rhodopsin and isorhodopsin, and there is no direct conversion between rhodopsin and isorhodopsin. Furthermore, rhodopsin converts to hypsorhodopsin or bathorhodopsin much more efficiently than does isorhodopsin, and bathorhodopsin does not convert directly to hypsorhodopsin. It was also found that rhodopsin and isorhodopsin convert to bathorhodopsin more efficiently than to hypsorhodopsin. In particular, the quantum yield of conversion from rhodopsin to bathorhodopsin was found to be about twice as large as that from rhodopsin to hypsorhodopsin. This result is somewhat in disagreement with the result obtained from the laser flash experiments at room and liquid nitrogen temperatures. The reason for the difference between the two experimental results is discussed.

Photochemical reactions in a commerical poly(ether sulfone)

A commercial poly(ether sulfone) has been examined by electronic spectroscopy, continuous photolysis, and laser flash techniques. The spectroscopic experiments indicate that the chromophoric species primarily responsible for light absorption in the region 290–350 nm is the diphenyl sulfone unit. The laser flash experiments give direct evidence of bond scission at the ether linkage on the polymer backbone.