It is shown that the lineshape function formula in the mean-phonon approximation reported by Hayes et al. [J. Phys. Chem. B 1994, 98, 7332] contains inconsistencies in notation, leading to essentially incorrect expressions in cases of moderate and strong electron-phonon (el-ph) coupling strengths. A corrected lineshape function L(ω), with proper dependence on the number of phonons involved in the transition, is given that retains the computational and intuitive advantages of the expression of Hayes et al. Although the corrected lineshape function could be used in modeling studies of various optical spectra, including transient hole burned (HB) spectra, we suggest that it is better to calculate the lineshape function and/or optical spectra numerically. Examples shown include new theoretical fits of the P870 and P960 absorption bands and frequency dependent resonant HB spectra of Rb. sphaeroides and Rps. viridis reaction centers. Comparison with the previously determined el-ph coupling parameters [Johnson et al. J. Phys. Chem. 1990, 94, 5849; Lyle et al. J. Phys. Chem. 1993, 97, 6924; Reddy et al. J. Phys. Chem. 1993, 97, 6934] is also provided using both Gaussian-Lorentzian and lognormal spectral densities, J(ω). The new fits lead to modified el-ph coupling strengths and different frequencies of the special pair marker modes, ωsp, that could be used in future more advanced calculations of absorption and HB spectra obtained for various bacterial reaction centers.

Comments on the optical lineshape function: Application to transient hole burned spectra of bacterial reaction centers

249th National Meeting (2015)

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