Ultraviolet Absorption Spectra of Methylnaphthalenes at 77°K

Abstract

A simple and reliable apparatus has been developed for the determination of low‐temperature ultraviolet absorption spectra in rigid glass media. This apparatus is particularly suitable for the measurement of accurate absorption intensities and has been used for the determination of the ultraviolet absorption spectra of naphthalene, 2‐methylnaphthalene, and 2,6‐dimethylnaphthalene at the temperature of boiling nitrogen (77°K). A comparison of these low‐temperature spectra provides evidence that the electronic transition of naphthalene in the 2900—3200 A range is symmetry allowed.