The Ultrafast Energy Transfer Process in Purple Bacteria

The Ultrafast Energy
Transfer Process in Purple Bacteria Photosynthetic Reaction Center

GUO Li-Jun^1,2*, MA Guo-Hong^1,2, ZOU
Yong-Long³, YANG Yi^1,2, LIU Yuan³, XU Chun-He³,
QIAN Shi-Xiong¹
(¹Physics Department of Fudan University, Shanghai 200433,
China；²National Key Laboratory of Applied
Surface Physics, Fudan University, Shanghai 200433, China；³Shanghai Institute of Plant
Physiology, the Chinese Academy of Science, Shanghai 200032, China )

Abstract    The
ultrafast energy transfer process, which takes place in femtosecond time range,
in bacterial photosynthetic reaction center RS601 was investigated using
femtosecond pump-probe technique with selective excitation. Upon 755 nmexcitation,
the excited state of bacteriopheophytin H decayed to bacteriochlorophyll B with
a time constant of about 130 fs, while the excited state of B transported the
energy to its energy acceptor, the dimeric bacteriochlorophyll P, in about 240
fs with the 800 nm excitation. The internal conversion process between the
upper and lower exciton levels of special pair P might exist upon the
excitation of 850 nm pulses. In addition, from the results obtained in our
experiments, the charge separation and electron transfer from P to the acceptor
H was also observed via the real intermediate B within a few picoseconds.
Key words    photosynthetic reaction center； energy transfer； ultrafast process

^*Corresponding author： Tel, 86-21-65642373； e-mail, [email protected]