Time Variations in the FTIR Spectra of Liquids Measured in the ATR Configuration

Attenuated total reflection (ATR) is often employed in the measurements of FTIR spectra. Such a configuration is convenient for experiments with liquid samples, since pressing them to the surface of the ATR crystal is not necessary. Spectral changes that occur in the course of measurements with liquids are revealed. It is shown that significant variations in the concentrations of components may occur in the ATR-FTIR measurements of solutions. Redistribution of components of a solution in the vicinity of the ATR crystal may lead to inhomogeneity of the sample.