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

The mixed crystal C/sub 10/H/sub 8/in C/sub 10/D/sub 8/ provides a 100- cm/sup -1/ trap. A crystal of high chemical purity containing 0.5% C/sub 10/H/ sub 8/ was studied in emission between 4.7 and 77 deg K on a 2-m grating spectrograph. Results and conclusions are listed. (L.N.N.)