Effects of the distributions of energy or charge transfer rates on spectral hole burning in pigment-protein complexes at low temperatures

51 Pags, 2 Tabls., 7 Figs. The definitive version is available at: http://pubs.acs.org/journal/jpcbfkEffects of the distributions of excitation energy transfer (EET) rates (homogeneous line widths) on the non-photochemical (resonant) spectral hole burning (SHB) processes in photosynthetic chlorophyll-protein complexes (reaction center [RC] and CP43 antenna of Photosystem II from spinach) are considered. It is demonstrated that inclusion of such a distribution results in somewhat more dispersive hole burning kinetics. More importantly, however, inclusion of the EET rate distributions strongly affects the dependence of the hole width on the fractional hole depth. Different types of line width distributions have been explored, including those resulting from Förster type EET between weakly interacting pigments as well as Gaussian ones, which may be a reasonable approximation for those resulting, for instance, from so-called extended Förster models. For Gaussian line width distributions it is possible to determine the parameters of both line width and tunneling parameter distributions from SHB data without a priori knowledge of any of them. Concerning more realistic asymmetric distributions, we demonstrate, using the simple example of CP43 antenna, that one can use SHB modeling to estimate electrostatic couplings between pigments and support or exclude assignment of certain pigment(s) to a particular state.Financial support from NSERC, CFI, Concordia University and Libyan government (S.A.) is gratefully acknowledged. R.P. thanks the MICINN (Grant AGL2008-00377) and the EU FEDER Program (AGL2008-00377) in Spain, and M.S. the US Department of Energy’s Photosynthetic Systems Program within the Chemical Sciences, Geoscience, and Biosciences Division of the Office of Basic Energy Sciences under NREL Contract #DEAC36- 08-GO28308 for support. R.J. acknowledges support from the NSF under grant CHE-0907958.Peer reviewe