Abstract
For pt. IX see abstr. A36447 of 1970. Expressions are derived for the host and guest fluorescence response functions and quantum yields of thin and thick, pure and mixed organic crystals. In addition to exciton migration and transfer, the effects of host exciton traps and of radiative migration and transfer are considered. Host exciton traps and radiative migration are shown to be important in thick anthracene and mixed anthracene-tetracene crystals.