Integrated molar absorptivity of mid- and far-infrared spectra of glycine and other selected amino acids
Abstract
A selection of five proteinogenic amino acids, namely glycine, isoleucine, phenylalanine, tyrosine and tryptophan were studied in the mid-infrared and in the far-infrared with the purpose to facilitate the search and identification of these astrobiological and astrochemical relevant molecules in space environments. The molar extinction coefficients (ε) of all mid- and far-infrared bands were determined as well as the integrated molar absorptivities (). The mid-infrared spectra of the five selected amino acids were recorded also at three different temperatures from -180C to ambient temperature to +200C. We measure the wavelength shift of the infrared bands caused by temperature and, for the most relevant or temperature-sensitive infrared bands, a series of linear equations were determined relating wavelength position with temperature. Such equations may provide estimates of the temperature of these molecules once detected in astrophysical objects and with the reported values of ε and , it will be possible to estimate the relative abundance of these molecules in space environments.