Abstract: The energy transfer and charge separation in the isolated PSⅡ particles and core complexes from spinach were studied with femtosecond absorption spectroscopy by exciting the PSⅡ particles and core complexes directly at 400 nm and probing them in the wavelength range of 520 to 700 nm with 200 fs resolution. The results from PSⅡ particle excitation showed that the processes of 0.16 ps, 2.8 ps and 20.9 ps components obtained by global analysis of data were the energy transfers occurred in the light-harvesting complexes Ⅱ (LHCⅡ ). The process of 8.6 ps component was the energy transfer from LHCⅡ to PSⅡ core and finally to the reaction center. The other result from PSⅡ core comple excitation showed that the 0.35 ps and 11.2 ps components attributed to the energy transfer among the internal antennae. It was concluded that the 2.9 ps and 20.1 ps components could be attributed to the charge separation processes or the energy transfer processes between core antennae and reaction center.

Key words: Femtosecond absorption spectroscopy, Primary processes, Energy transfer, Photosystem Ⅱ