Predissociation in Fluorescence Emission Spectra: Fluorescence of Acetone Vapour

Abstract

THE fluorescence of acetone was first observed by Gelbke¹. It was also observed independently in the vapour by Mr. C. W. Woolgar of King's College, London, who kindly directed our attention to its existence. Recently, Damon and Daniels², in a paper on the photochemical decomposition of acetone, have described the visible fluorescence of acetone vapour as a greenish emission consisting of two diffuse bands, one extending from 4100 to 4820 A., the other from 4990 A. to the limit of the sensitivity of the plate (5210 A.). They record that the intensity is reduced and the colour of the fluorescence changed to blue by the addition of oxygen or air, but that the bright green fluorescence is restored after a period of illumination. These changes are readily explained by the specific quenching action of oxygen due to photochemical oxidation, which is known to occur. The excited molecules of acetone upon reaction lose their power to fluoresce, while the blue fluorescence is the product of a transient intermediate compound present during the process of oxidation.