Infra-Red Spectra of Hydrocarbons I. Some Investigations of the Temperature Dependence of Absorption Bands

Abstract

Theory indicates that the separation of the maxima of the P and R branches of an infra‐red band should be proportional to the square root of the absolute temperature. This relation has been tested by experiments with ethane, propylene and 2, 2‐dimethyl butane in which the temperature was varied between − 195°C and room temperature. It has been found that the relation is approximately valid, the band widths being somewhat less than theory predicts in the liquid and considerably less in the solid. The positions of the bands are independent of the temperature in 2, 2‐dimethyl butane and only slightly affected in the other compounds. Some bands of propylene display a pronounced variation in relative intensity with temperature. The usefulness of spectra obtained at low temperatures in the theoretical assignment of fundamentals, as a tool for the study of the liquid state and for analytical purposes, is pointed out.