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 v̄_max 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.