Anisotropic circular dichroism (ACD) spectroscopy of macroscopically aligned molecules reveals additional information about their excited states that is lost in the CD of randomly oriented solutions. ACD spectra of light-harvesting complex II (LHCII)-the main peripheral antenna of photosystem II in plants-in oriented lipid bilayers were recorded from the far-UV to the visible wavelength region. ACD spectra show a drastically enhanced magnitude and level of detail compared to the isotropic CD spectra, resolving a greater number of bands and weak optical transitions. Exciton calculations show that the spectral features in the chlorophyll Q y region are well-reproduced by an existing Hamiltonian for LHCII, providing further evidence for the identity of energy sinks at chlorophylls a603 and a610 in the stromal layer and chlorophylls a604 and a613 in the luminal layer. We propose ACD spectroscopy to be a valuable tool linking the three-dimensional structure and the photophysical properties of pigment-protein complexes.

Biological Research Centre Hungarian Academy of Sciences Temesvári krt 62 6726 Szeged Hungary

Diamond Light Source Ltd Harwell Science and Innovation Campus Didcot Oxfordshire OX11 0DE U K

ELI ALPS ELI HU Nonprofit Ltd Budapesti út 5 6728 Szeged Hungary

Faculty of Science and Informatics Doctoral School of Physics University of Szeged Dóm tér 9 6720 Szeged Hungary

Faculty of Science Department of Physics University of Ostrava Chittussiho 10 710 00 Ostrava Czech Republic

Institute for Theoretical Physics Johannes Kepler University Linz Altenberger Str 69 4040 Linz Austria

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Editorial

Time-resolved circular dichroism of excitonic systems: theory and experiment on an exemplary squaraine polymer

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