TRIPLET-STATE OF THE CHLOROPHYLL DIMER

The photoexcited triplet state properties of chlorophyll aggregate systems in vitro were investigated by zero-field optically detected magnetic resonance (ODMR) spectroscopy at 2 K. Measurements of the triplet state zero-field splittings, over-all triplet lifetimes, and individual spin sublevel intersystem crossing rate constants were obtained for solutions of chlorophyll a and zinc-substituted chlorophyll a and for the covalently linked dimeric derivative of pyrochlorophyllidea. The triplet-state properties found for these systems are interpreted within the framework of the triplet cxciton model to assess the applicability of the exciton approach in determining the geometry of chlorophyll aggregate systems and to evaluate structural features of chlorophyll systems proposed as models for in vivo chlorophyll. © 1979, American Chemical Society. All rights reserved.