Excited-state dynamics of rhodopsin probed by femtosecond fluorescence spectroscopy

Nonexponential fluorescence dynamics of bovine rhodopsin were measured at v arious wavelengths from 530 to 780 firn. No dynamic Stokes shift was detect ed but the fastest part of the fluorescence at both blue and red sides of t he spectrum decayed faster than that at the center, which has led to the co nclusion that the Franck-Condon state --> fluorescence state conversion occ urs within time-resolution of apparatus (<100 fs) owing to coupling with in tra-chromophore high frequency modes and faster initial decay is due to sha rpening of band shape caused by a decrease of amplitudes of hfm along the r eaction coordinate of twisting. (C) 2001 Elsevier Science B.V. All rights r eserved.