Abstract: | Abstract— This paper discusses the possibility of triplet exciton motion and triplet-triplet annihilation in mixed crystal systems in which the hosts are phenylalanine, tyrosine and trypto-phan and in four protein systems. Triplet-triplet annihilation and triplet transfer are observed in certain phenylalanine- and tryptophan-host systems. No evidence of either triplet transfer or energy multiplication is found in tyrosine-host crystal systems or in any protein system. |