Tripletmdash;Singlet Luminescence from Methylated Benzenes in the Crystalline State and in Rigid Glass Solutions

摘要

In continuation of earlier studies, tripletmdash;singlet emission of the following methylated benzenes is reported in their solid phases: mesitylene, durene, hexamethylbenzene. The spectra were obtained in rigid EPA solutions at 77deg;K, and in the crystalline state at 77deg; and at 4deg;K. Two different spectra were found for mesitylene and durene crystals, one at shorter wavelengths representing the genuine tripletmdash;singlet emission of the substance, and the other at longer wavelengths belonging to the lowest phosphorescence of an oxidation product. Hexamethylbenzene crystal apparently exhibits only one spectrum at any temperature. No solution spectrum was obtained for it because of its poor solubility. For an interpretation of the observations, various processes which take place in these crystals upon light illumination are discussed.