Confirmation of the Anomalous Fluorescence of Azulene

Abstract

The light emission properties of the azulene molecule and several alkyl-substituted azulenes have been studied. In confirmation of recent results of Beer and Longuet-Higgins, it is found that anomalous (S″→S) fluorescence occurs in azulene, with v̄max at 26 802 cm—1 (rigid glass solution in EPA at 77°K). Red-shifts for this fluorescence are found in several alkyl-substituted azulenes, in qualitative agreement with substitution theory. The absence of normal (S′→S) fluorescence and the absence of any phosphorescence (T→S) emission to 11 000 A, the apparatus limit, are also confirmed. The emission observations are discussed, and alternative interpretations are given.