DIFFUSENESS IN ELECTRONIC SPECTRA THE VAPOR SPECTRUM OF ANTHRACENE

Abstract

Approximate calculations of the number of rovibronic transitions per unit wavenumber are given for benzene, naphthalene, anthracene, and tetracene. Primarily because of the density of sequence structure all transitions in tetracene vapor should be irresolvably crowded, and hence apparently diffuse, at practical temperatures. Anthracene, whose spectrum has hitherto been described as wholly diffuse, is predicted to be capable of showing resolvable structure at room temperature. At 60 °C and 40 m path a short region of fine sharp structure has been observed. The origin of the first singlet transition is located at 27 688.3 cm⁻¹ (27 757.6 cm⁻¹ in anthracene-d₁₀).