Laser-induced hole filling in reaction center of photosystem II

Laser-induced hole-filling of a primary hole (at lambda(pri)) after burning of a secondary hole (at lambda(sec)) was measured in Q(y) absorption spect ra of the photosystem II reaction center at 4.2 K. The areas of the primary burnt holes were filled more for lambda(pri) > lambda(sec) than for lambda (pri) < lambda(sec). The observed laser-induced hole filling kinetics follo wed biexponential decays for lambda(pri) > lambda(sec), while for lambda(pr i) < lambda(sec) they were only monoexponential. Two different laser-induce d hole filling mechanisms were connected with two different decay parameter s. The first laser-induced hole filling mechanism was interpreted as photoi nduced relaxation of the protein matrix, while the second one was due to ex cited energy transfer in the reaction center of photosystem II. (C) 2000 El sevier Science B.V. All rights reserved.