Excited-state properties of biliproteins:: I.: phytochrome Pr

Phytochrome Pr has been investigated by means of picosecond intensity-dependent transmission measurements at several excitation wavelengths inside the S-0 --> S-1 absorption band. The experimental data exhibit relatively strong excited-state absorption (ESA) within the whole spectral range of the S-0 --> S-1 absorption, which is followed by fast relaxations on the femtosecond time scale ( < 200 fs). The ESA cross sections at wavelengths below 640 nm are lower than those of the ground-state absorption, but they are noticeably larger at the maximum and at the long-wavelength side where stimulated emission additionally influences the bleaching behaviour. The spectral characteristics of the emission cross sections have been shown to be a good measure for the comet radiative Lifetime ro. This confirmed our recently published value of tau(0) = 4.9 ns. (C)1999 Elsevier Science S.A. All rights reserved.