Synchronous Measurement of Ultrafast Anisotropy Decay of the B850 in Bacterial LH2 Complex
WANG Yun-Peng, DU Lu-Chao, ZHU Gang-Bei, WANG Zhuan, WENG Yu-Xiang**
Laboratory of Soft Matter Physics, and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190
Abstract：Ultrafast anisotropic decay is a prominent parameter revealing ultrafast energy and electron transfer; however, it is difficult to be determined reliably owing to the requirement of a simultaneous availability of the parallel and perpendicular polarized decay kinetics. Nowadays, any measurement of anisotropic decay is a kind of approach to the exact simultaneity. Here we report a novel method for a synchronous ultrafast anisotropy decay measurement, which can well determine the anisotropy, even at a very early time, as the rising phase of the excitation laser pulse. The anisotropic decay of the B850 in bacterial light harvesting antenna complex LH2 of Rhodobacter sphaeroides in solution at room temperature with coherent excitation is detected by this method, which shows a polarization response time of 30 fs, and the energy transfer from the initial excitation to the bacteriochlorophylls in B850 ring takes about 70 fs. The anisotropic decay that is probed at the red side of the absorption spectrum, such as 880 nm, has an initial value of 0.4, corresponding to simulated emission, while the blue side with an anisotropy of 0.1 contributes to the ground-state bleaching. Our results show that the coherent excitation covering the whole ring might not be realized owing to the symmetry breaking of LH2: from C9 symmetry in membrane to C2 symmetry in solution.
. [J]. 中国物理快报, 2015, 32(02): 23101-023101.
WANG Yun-Peng, DU Lu-Chao, ZHU Gang-Bei, WANG Zhuan, WENG Yu-Xiang. Synchronous Measurement of Ultrafast Anisotropy Decay of the B850 in Bacterial LH2 Complex. Chin. Phys. Lett., 2015, 32(02): 23101-023101.
2015, Vol. 32 
