A Vibrational Analysis of the Fluorescence of Naphthalene Vapor

Abstract

The fluorescence spectrum of naphthalene vapor has been photographed and found, under suitable conditions, to consist of a number of discrete bands. Thirty‐nine bands were measured and a vibrational analysis was carried out making use of assignments of infrared and Raman fundamentals. The analysis indicates that the transition observed is forbidden by symmetry and made weakly allowed by a molecular vibration of frequency 478 cm⁻¹ belonging to the representation b2_u. This indicates that the wave function of the lowest excited singlet state of naphthalene belongs to the irreducible representation A_g or B1_g of the point group D2_h.