Photophysical triplet state processes of 4-H-1-benzopyrane-4-thione in a perfluoroalkane. Part 2.—Delayed S <sub>2</sub> → S <sub>0</sub> fluorescence due to triplet–triplet annihilationHeike Eisenberger, Ronald P. Steer, Bernhard Nickel et al.|Journal of the Chemical Society Faraday Transactions|1996Cited by 25