Excitonic energy transfer processes in photosynthetic systems studied with two-dimensional electronic spectroscopy

Abstract

In photosynthesis, excitonic energy transfer (EET) processes amongst pigment-protein complexes have a significant role in determining the overall efficiency of the photosynthesis activity. Photosystem II (PSII) is responsible for the first steps of plant and algal photosynthesis, including harvesting of sunlight energy and its ensuing transport. With the development of ultrafast spectroscopic techniques, information about the energy transfer processes in PSII pigment-protein complexes can be obtained with high time resolution and broad bandwidths. In this thesis, two-dimensional electronic spectroscopy (2DES) is employed to study the EET dynamics in various sets of subunits that make up the natural PSII supercomplex. 2DES together with phenomenological and structure-based modelling proves to be an effective approach to study EET processes in PSII. The observations of EET dynamics in the PSII pigment-protein complexes at both intra- and inter-complex levels provide direct insights into the operation principles of the photosynthesis activity. In addition to photosynthetic systems, this thesis also shows another possibility among the diverse applications of 2DES in studying the ultrafast spectral diffusion and vibronic coupling dynamics in nanomaterials, specifically CdSe colloidal quantum wells.