The Infrared Spectrum of Ethylene Oxide Clathrate Hydrate at 100°K between 4000 and 360 cm−1

Abstract

The infrared spectra of characterized samples of ethylene oxide hydrate made from 100% H2O, 99.7% D2O, and several dilute isotopic solutions, are presented between 4000 and 360 cm−1. The similarity between the absorption by the water molecules in the hydrate and in ice I is discussed. The frequency and halfwidth of the OH and OD stretching modes of isolated HDO molecules in the hydrate are related to those in the disordered ice phases; the frequencies correlate rather well with the weighted-mean hydrogen bond lengths in these phases.The ethylene oxide vibrations show sharp, single-line absorption. The only exceptions are the ring-breathing mode which appears as a doublet, separated by 2 cm−1, with much weaker absorption about 13 cm−1 away on either side, and the ring deformation modes which interact with the vR(H2O) modes. The possible causes of this behavior are discussed, but no firm conclusions can be drawn. The sharpness of the absorption by enclathrated ethylene oxide, compared to that by liquid ethylene oxide, is briefly discussed in the light of modern theories of bandshapes in liquids.