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STUDIES OF REAL AND ARTIFICIAL PHOTOSYNTHETIC SYSTEMS.

Objective

THE UNDERSTANDING GAINED WILL BE EXPLOITED IN WHATEVER WAYS SEEM PROMISING FOR THE IMPROVEMENT OF NATURAL PHOTOSYNTHESIS OR THE DESIGN OF SYNTHETIC SOLAR ENERGY SYSTEMS. PARALLEL THEORETICAL STUDIES OF THESE PROCESSES WILL BE PURSUED.

THIS REPORT SUMMURISES THE WORK CARRIED OUT DURING THE 8 MONTHS BETWEEN THE BEGINNING OF THE CONTRACT (APRIL 1ST 1986) AND DECEMBER 31ST 1986. THE PRINCIPAL ACHIEVEMENTS HAVE BEEN (1) THE DEVELOPMENT OF A PICOSECOND AND SUB-PICOSECOND LASER FLASH PHOTOLYSIS EQUIPMENT WHICH INCORPORATES A WHITE-LIGHT PROBE FOR TRANSIENT ABSORPTION SPECTROSCOPY AND (2) THE APPLICATION OF THE EQUIPMENT TO THE STUDY OF THE KINETICS OF LIGHT HARVESTING AND ENERGY TRANSFER IN PARTICLES OF PHOTOSYSTEM I ISOLATED FROM CHLOROPLASTS.

PSI REACTION CENTRE COMPLEXES WITH A CHLOROPHYLL/P700 RATIO OF 50, CHEMICALLY REDUCED PRIOR TO EXCITATION, SHOWED CLEARLY THE GROW-IN, WITH A HALF-LIFE OF 15 PS, OF THE BLEACHING OF P700 DUE TO OXIDATION FOLLOWING ENERGY TRANSFER FROM THE ANTENNA CHLOROPHYLLS. NO SUCH CHANGE IN P700 WAS OBSERVED WHEN THE PREPARATION WAS OXIDISED PRIOR TO EXCITATION, THOUGH THE BLEACHING OF ANTENNA CHLOROPHYLLS OCCURED INDEPENDENTLY OF THE REDOX STATE.
STUDIES OF THE EFFECT OF CHANGING THE PUMP INTENSITY SHOWED THAT, AT THE HIGHER INTENSITIES, OXIDATION OF P700 WAS COMPLETE. STIMULATED EMISSION CONTRIBUTES TO THE DIFFERENCE SPECTRA AND ITS CONTRIBUTION HAS BEEN CALCULATED AND ALLOWANCE MADE.

FURTHER WORK IS IN PROGRESS TO OBSERVE THE SUBSEQUENT ELECTRON-TRANSFER STEPS. INVESTIGATIONS OF PS2 PARTICLES HAVE ALSO BEGUN, AS WELL AS STUDIES OF ENERGY TRANSFER WITHIN ISOLATED LHC COMPLEXES.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

THE ROYAL INSTITUTION OF GREAT BRITAIN
Address
Albermarle Street 21
W1X 4BS London
United Kingdom

Participants (1)

IMPERIAL COLLEGE OF SCIENCE, TECHNOLOGY AND MEDICINE
United Kingdom
Address

London