
%0 Journal Article
%A Kimura, A 
%A Yamato, T 
%T A new formula of exciton coherence length in linear array of pigments
%J Science Access
%D 2001/01/01
%V 3
%N 1
%P -
%K 
%R https://doi.org/10.1071/SA0403020
%U https://www.publish.csiro.au/paper/SA0403020 
%X By solving the generalized master equation with a memory function properly expressed by using the time-correlation function of the exciton-vibration interaction, we derived an empirical formula for the exciton coherence length Ncoh in the linear array of pigments as a function of exciton coupling U and the decay factor for excitation transfer g as follows:  Ncoh = 1.40 + 1.32 (U/g )  Adopting the intermediate coupling theory of exciton in dimer (Kimura et al., J. Phys. Chem. B 104 (2000) 9276), we can express the decay factor g by using the reorganization energy l and energy gap D G due to the excitation transfer between neighboring pigments. Applying this general formula to the B850 ring of LH2 of photosynthetic purple bacteria (U = 350 cm-1, l = 80 cm-1 and so g = 140 cm-1), we obtain Ncoh = 4.7. When we evaluate g by considering the Gaussian inhomogeneous broadening (HWHM 200 cm-1), we obtain Ncoh = 3.2. Namely, the exciton domain extends only 3-4 BCl units among the 18 BCl units of B850 in LH2. 
