The Absorption Spectrum of Phenanthrene Crystals Beyond 3000 Å

Abstract

Abstract The polarized absorption spectra of phenanthrene and phenanthrene-d10 crystals have been measured at 4°K, 77°K, and room temperature from 33,000 cm−1 to a cutoff at 37,500 cm−1. The absorption, which rises steeply towards shorter wavelengths and is twice as intense in the b-as in the a-polarized spectrum, corresponds to the moderately weak 3000 A system superimposed on the tail of the intense 2500 A system. The former is assigned to a B2—A1, and the latter to an A1—A1 transition. No measurable Davydov splitting was observed in the 3000 A system.