Research topic. The photosynthetic conversion of solar energy to chemical energy is by no comparison the most important energy process on earth. The biosphere is dominated by the oxygen evolving (or water oxidizing) organisms i.e. plants, algae and cyanobacteria. These use water as substrate: thereby they can live almost everywhere. The key reaction is the light-driven oxidation of water that provides the biosphere with an unlimited electron source. This fundamental reaction is carried out by Photosystem II, which oxidizes water to oxygen and protons. This seems to be a simple reaction, but in nature only PSII reaches potentials (>+lV) high enough to oxidize water. The difficulty is also clear from chemistry and there exists few, if any, man-made catalyst s able to carry out the reaction.

The applicant will study the mechanism of the oxygen evolving machinery (water oxidizing complex) in Photosystem II (PSII). In particular we concentrate on proton currents between the Mn-cluster and the tyrosine in the intermediate redox states (S-states). We study these components by state-of-the-art EPR spectroscopy in synchronized PSII centres at different pH,by illumination at ultra-low temperature etc. The intention is to bring the applicant up-to-date in the use of EPR spectroscopy and other biophysical techniques, a topic at the forefront of today's biophysical research. The oxidative chemistry and the biochemistry in PSII offer a range of highly interesting and unique reactions. The applicant will focus on these reactions in his research.

Training program. The applicant has chosen the group to learn and use sophisticated EPRspectroscopy. This will be accomplished by EPR courses specifically designed to fit the applicant's needs to carry out his research project. The training program also contains courses in photosynthesis, participation in outside courses in EPR and other relevant activities at outside institutions.