ESR study of the hyperfine structure of the triplet state in crystalline donor acceptor complexes: A probe for the degree of charge transfer in the excited state

The hyperfine tensors of the triplet states of several guest donor molecules in naphthalene/tetracyanobenzene host crystals have been measured by EPR spectroscopy. From these data the degree of charge transfer (b2) in the excited state can be derived in a straightforward way. Whereas anthracene yields values almost identical with those characteristic for the isolated molecule (b2 ≈ 0.05), phenanthrene shown a significant degree of charge transfer in the triplet state (b2 ≈ 0.47). © 1976.