Retardation of singlet and triplet excitation migration in organic crystals by isotopic dilution

The Triplet State and Molecular Electronic Processes in Organic Molecules

“…Very soon, however, a number of experimental studies had demonstrated triplet energy migration between (dilute) guest molecules in molecular crystals. The sensitized phosphorescence experiments of Robinson's group (86,264,265,376) elucidated the nature of guest-to-guest triplet migration in mixed crystals, and provided an estimate (265) of the triplet interaction matrix element that was much larger than had been thought likely. Hutchison (31) showed that triplet transfer in biphenyl host crystals is definitely a long-range process, and not an artifact of complexing or accidental juxtaposition of donor and acceptor molecules.…”