ABSORPTION OF INFRARED RADIATION BY MOLECULES

V. N. Filimonov. Induced absorption of infrared radiation by molecules. Sov. Phys. USPEKHI, 2 894, 1960. 

The Beer-Lambert rules derived above (equation 7.3) apply equally to absorption of infrared radiation by molecules. Moreover, infrared absorption spectra possess an advantage over the more common ultraviolet absorption in the greater number of bands present. It is often possible to select an absorption band for each component of a mixture such that little or no interference occurs between them. For these reasons, infrared spectroscopy is often used quantitatively in the analytical laboratory to determine drug concentrations in solution. A calibration curve for the assay may be obtained (and Beer s law confirmed) by converting the printed spectrum... 

The absorption of infrared radiation by molecules and compounds arises from the interaction of interatomic vibations of various sorts with the energy contained in infrared radiation. 

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