Abstract

Recent femtosecond and picosecond measurements of the primary charge separation event in photosystem II have resulted in a controversy with regard to the time constant for the primary charge separation process. Klug and coworkers have published a series of papers in support of a ca. 20 ps effective time constant for the appearance of the charge-separated state [1]. Their conclusions are supported by the experiments of McCauley et al. [2] and Freiberg et al. [3]. On the other hand, several groups have published data interpreted as supporting a ca. 3 ps time constant for the primary charge separation [4-6]. In light of this disagreement we have performed a series of subpicosecond transient absorption measurements on the reaction center of PSII. These studies have concentrated on the effect of pump intensity, pump wavelength, and method of sample preparation.

© 1996 Optical Society of America