Abstract
Photosystem I (PSI) of Acaryochloris marina (A. marina) employs chlorophyll d (Chl d) as the major pigment. We have clarified the difference between the Chl d-based PSI and more conventional Chl a-based PSI by using femtosecond transient absorption (FTA) measurement. In this contribution, we report the details of the energy transfer and its effects on the charge separation dynamics in A. marina PSI. We have compared the FTA spectra between excitation wavelengths at 630 nm and 730 nm. Regardless of the excitation wavelength, there are two phases in the trapping of the excitation energy by the primary charge separation with time constants of 3 - 5 ps and 30 - 50 ps. An intermediate charge-separated state, which is characterized by a transient photobleaching at 680 nm, was found to be generated prior to the photobleaching of the electron-donor chlorophyll (P740), under both the excitation conditions.
