Technical Progress Report Radiationless Energy Conversion of Photoexcited Triplet States of Organic Molecules Progress Report for May 1, 1975 - April 30, 1977

摘要

During the initial two years of our ERDA-supported research program we have attempted to define and understand the mechanisms active in the intersystem crossing processes of large polycyclic hydrocarbons and chlorophyll. To study these excited states energy conversion processes we have utilized optical detection of magnetic resonance spectroscopy, as developed in our laboratory, which is uniquely applicable to these molecular systems. Our results on polycyclic hydrocarbons have shown that an understanding of triplet state radiationless transitions in planar arc ratic molecules can be obtained from a consideration of the symmetry-selected spin-orbit interactions and positions of available mixing states;this work provides a predictive model of triplet state nonradiative energy conversion with general applicability to aromatic systems. This treatment has been applied successfully to chlorophyll triplet state dynamics and provides a basis for the utilization of the triplet state of chlorophyll as a (nondestructive tive) spin probe into the makeup of more complex chlorophyll-containing systems in vitro and in vivo.