Nickel, B., Eisenberger, H., Wick, M. T., & Steer, R. P. (1996). Photophysical triplet state processes of 4H-1-benzopyrane-4-thione in a perfluoroalkane.3. Excitation wavelength dependence of luminescence quantum yields. Journal of the Chemical Society-Faraday Transactions, 92(7), 1101-1104.