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Interaction between Excitons and Radiation‐Induced Radicals in Naphthalene Single Crystals
Author(s) -
Chong T.,
Itoh N.
Publication year - 1976
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220740111
Subject(s) - chemistry , photochemistry , radical , singlet state , reaction rate constant , triplet state , excited state , quenching (fluorescence) , exciton , fluorescence , atomic physics , kinetics , physics , condensed matter physics , organic chemistry , quantum mechanics
Correlation between the fluorescence of a radiation‐induced radical and the quenching of the prompt and delayed fluorescence by the radicals has been studied in naphthalene single crystals. It is found that the fluoresceme of the I‐hydronaphthyl radical is induced by energy transfer from both the singlet and triplet excitons. The interaction rate constant k s between the singlet exciton and the radical is obtained as 6 × 10 −9 and 8 × 10 −9 cm 3 s −1 at 290 and 80 K, respectively. Quenching of the delayed fluorescence by the radical is explained by reaction kinetics which involves not only the triplet‐triplet annihilation and a direct collision of a triplet exciton with the radical but also a collision of a triplet‐radical complex or the radical at the excited state with another triplet exciton. The interaction rate constant k T between the triplet exciton and the radicals is obtained as 2 × 10 −11 and 3 × 10 −11 cm 3 s −1 at 290 and 80 K, respectively. It is concluded that the interaction rate constant γ between the triplet exciton and the triplet‐radical complexes or the radical at the excited state is larger than k T which is larger than the rate constant γ for the triplet‐triplet annihilation. It is also shown that the temperature dependences of γ and k T are parallel.