title: Selective and differential optical spectroscopies in photosynthesis.
abstract: Photosynthetic pigments are inherently intense optical absorbers and have strong polarisation characteristics. They can also luminesce strongly. These properties have led optical spectroscopies to be, quite naturally, key techniques in photosynthesis. However, there are typically many pigments in a photosynthetic assembly, which when combined with the very significant inhomogeneous and homogeneous linewidths characteristic of optical transitions, leads to spectral congestion. This in turn has made it difficult to provide a definitive and detailed electronic structure for many photosynthetic assemblies. An electronic structure is, however, necessary to provide a foundation for any complete description of fundamental processes in photosynthesis, particularly those in reaction centres. A wide range of selective and differential spectral techniques have been developed to help overcome the problems of spectral complexity and congestion. The techniques can serve to either reduce spectral linewidths and/or extract chromophore specific information from unresolved spectral features. Complementary spectral datasets, generated by a number of techniques, may then be combined in a 'multi-dimensional' theoretical analysis so as to constrain and define effective models of photosynthetic assemblies and their fundamental processes. A key example is the work of Renger and his group (Raszewski, Biophys J 88(2):986-998, 2005) on PS II reaction centre assemblies. This article looks to provide an overview of some of these techniques and indicate where their strengths and weaknesses may lie. It highlights some of our own contributions and indicates areas where progress may be possible.
authors.affiliation: Research School of Chemistry, Australian National University, Building 35 Science Road, Canberra, ACT, 0200, Australia, krausz@rsc.anu.edu.au.
authors.forename: Elmars
authors.initials: E
authors.lastname: Krausz
mesh_terms: D055620:Optical Phenomena; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism; D013057:Spectrum Analysis / Q000379:methods*; D013816:Thermodynamics
chemical_list: D045332:Photosystem II Protein Complex