The effect of excitation wavelength dependence on the ground state absorption excited state stimulated emission, and the electron transfer process in reaction centers from the R-26 carotenoidless strain of the bacterium Rhodobacter sphaeroides was studied using time-resolved hole-burning spectroscopy. The P* state was prepared using 838, 858, 878, and 892 nm excitation pulses which had a temporal width of approximately 150 fs and a spectral width of about 60 cm-. The majority of the stimulated emission from P* moves to wavelengths greater than 890 nm, within the first 200 fs following excitation. If confirmational subpopulations do exist in the excited state with different rates of electron transfer, they appear to be distinct from the confirmational subpopulations in the ground state which give rise to the distribution of P → P* transition energies.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry