R. Bowling Barnes

The Analysis of Isotopic Mixtures of Deuteromethanes and Ethanes by Infrared Absorption Spectra

The infrared absorption spectra of a large number of deuterium‐containing methane samples, and a few of ethane, have been studied with a rocksalt spectrometer. All the observable fundamental frequencies of each individual methane isotope have been identified, and from the relative intensity of absorption at various characteristic wave‐lengths the composition of any mixture of these isotopes may be determined. The infrared spectra of deuteroethanes including C2D6 have been observed.

An Improved Wire Grating Spectrometer for the Far Infrared

A spectrometer of new design is described, which makes easier the investigation of the far infrared spectra of either solids, liquids or gases. With this instrument a very high degree of resolution has been obtained and several substances have been studied from 30μ to 180μ. From 30μ to 85μ the effective slit‐width was 1.04μ; from 85μ to 122μ, 1.67μ; and from 122μ to 180μ, 2.59μ.

Filters for the Infrared

A simple filtering system, involving the use of only two simply constructed selenium powder filters, is described, by the use of which it is possible to obtain a pure energy spectrum with a wire grating spectrometer in the region 40–130μ. In addition transmission curves are given for a number of substances in the regions 1–15μ and 35–130μ.

The Near Infrared Spectrum of Benzene‐d6

The transmission spectrum of C6D6 has been studied from 1μ to 13.25μ and the shifts of three of the four infrared active vibrations determined. The results obtained are in substantial agreement with the assumption of a plane symmetrical molecule as outlined by Wilson.Measurements on C6H6 and thiophene extending from 1μ to 15μ are also presented.

A Bilateral Slit Mechanism

A bilateral slit mechanism is described which is accurate in its performance and simple enough to be constructed in any laboratory workshop.