The absorption spectra of absolute ethyl alcohol and alcohol containing water were studied in the region from 1.5µ to 5µ. In the water-alcohol mixtures there appeared a band at 2.8µ not characteristic of either alcohol or water. For small concentrations of water the intensity of this band was found to increase with increasing water content. The presence of the band at 2.8µ was interpreted as indication of association between the water and alcohol molecules. This result is in agreement with the anomalous changes in volume and in specific heat which take place in mixtures of alcohol and water.
DUDLEY WILLIAMS, R. D. WEATHERFORD, and E. K. PLYLER, "The Infrared Absorption Spectra of Mixtures of Alcohol and Water," J. Opt. Soc. Am. 26, 149-151 (1936)