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Title: Organic photochemical storage of solar energy. Progress report, February 1, 1979-January 31, 1980

Technical Report ·
DOI:https://doi.org/10.2172/5654397· OSTI ID:5654397

Study of valence isomerization of organic compounds has focused on two mechanisms of photosensitization involving either electron donor-acceptor interaction or energy transfer. The quenching of fluorescent sensitizers by isomerizable substrates results in the formation of excited complexes. These sensitizer-substrate pairs are highly polarized, leading to changes in bond order for the substrates. For several substrates such as quadricyclene, hexamethyldewarbenzene, and a nonbornadiene derivative, this perturbation results in efficient valence isomerization. Isomerization observed on irradiation of charge transfer complexes of isomerizable substrates is consistent with a similar exciplex - template mechanism. The energy transfer mechanism of photosensitization has been studied by measuring the temperature dependence of quantum yield for isomerization of dimethyl norbornadiene-2,3-dicarboxylate sensitized by benzanthrone. From temperature and quencher concentration profiles quenching constants have been obtained which are consistent with an endoergic triplet energy transfer mechanism. The thermal upconversion of the low energy triplet of benzanthrone results in a threefold increase in isomerization quantum yield over a 90/sup 0/ temperature range.

Research Organization:
Boston Univ., MA (USA). Dept. of Chemistry
DOE Contract Number:
EG-77-S-02-4380
OSTI ID:
5654397
Report Number(s):
COO-4380-3
Country of Publication:
United States
Language:
English