Triplet-Singlet Emission Spectra of Solid Toluene at 4°K and 77°K and in EPA Solution at 77°K

Abstract

Phosphorescence of toluene has been studied at 4°K and 77°K in its solid phases (crystalline and amorphous) and in solid solution (EPA) at 77°K. The spectrum of the crystal at 4°K (3460‐4530 A) consists of sharp bands, and weaker diffuse bands which resemble in arrangement the rigid glass spectrum at 77°K. This emission has a lifetime of about 8 sec. The spectrum of solid toluene at 77°K (3950‐4900 A) has broad diffuse bands, and an estimated lifetime of ∼10^‐2‐10^‐3 sec. Its vibrational structure differs from that of the spectra at 4°K and in EPA, but resembles much the structure of the phosphorescence spectrum of benzaldehyde. The origin of the various spectra and the differences between them are discussed. The suggestion is made that benzaldehyde is produced photochemically and that its spectrum appears by a process of sensitization.