A PHYTOCHROME PHOTOTRANSFORMATION STUDY USING 2-LASER 2-COLOR FLASH-PHOTOLYSIS - ANALYSIS OF THE DECAY MECHANISM OF I(700)

The mechanism of I700 decay, representing a nearly event in the phytoc hrome P(r) --> P(fr) phototransformation, was reanalyzed in the micros econd range by conventional laser flash photolysis as well as by two-l aser/two-color flash photolysis. Three kinetic models that might descr ibe the I700 decay mechanism following P(r) excitation were considered : a parallel, a sequential, and an equilibrium model. These models wer e used to mathematically simulate both the one- and two-laser flash ex periments in an effort to select the model best describing the I700 de cay. The sequential model could be excluded already on the basis of th e one-laser flash photolysis results alone. Discussion of the two-lase r/two-color flash results in the context of the equilibrium and the pa rallel models is presented.