The intensity of absorption of naphthacene vapor from 20 000 to 54 000 cm −1

Abstract

Absorption band positions and oscillator strengths of transitions are reported for the naphthacene molecule over the spectral range 20 000–54 000 cm −1. The variation of band positions from vapor to solution to crystal is discussed. The intensities of absorption do not vary significantly from vapor to solution although a redistribution of intensity is evident in some transitions. The assignment of the π-π electronic transitions is discussed in terms of current theories of π-electronic spectra. Some bands which could be due to Rydberg transitions are detected but because of their breadth are not readily assigned. The enthalpy of sublimation is measured as 30.8 kcal mole −1 and the lattice energy at 200°C as 29.9 kcal mole −1.