Phosphorescence Bands of Quinones and α-Diketones

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Abstract
Phosphorescence bands, their life times, and the excitation spectra of anthraquinone, α-naphthoquinone, phenanthrenequinone, acenaphthenequinone, benzophenone, benzil, furil, and camphorquinone at 77°K in a rigid solution and in the crystalline state have been studied. In a rigid solution the lifetimes of these phosphorescence bands are in the range (10–0.1 msec). The solvent effect on lifetimes shows clear differences between o- and p-quinones. The behavior of these phosphorescence bands is similar to that of the n→π* bands of these compounds. From these facts, these bands are all safely identified as π*→n bands. The phosphorescence bands of p-quinones in the crystalline state are at far longer wavelengths than those in a rigid solution, and the lifetimes of the former are far longer than those of the latter. The dichroism of excitation spectrum of the phosphorescence band of anthraquinone proved that the phosphorescence band is polarized perpendicularly to the 320 mμ band and parallel to the 270 mμ band.