(infrared spectrometry) A powerful method for analyzing substances whether solids, liquids or gases; deals with transitions between vibrational energy levels in molecules, and is therefore also called vibrational spectroscopy; an IR spectrum is generally displayed as a plot of the energy of the infrared radiation (expressed either in microns or wavenumbers) versus the percent of light transmitted by the compound.

(infrared spectrometry) A spectrometric method that determines the type and concentration of elements or chemicals in a sample, based upon the principle that the atoms in a sample will vibrate or rotate at a specific frequency when exposed to infrared light.

(spectrophotometry, infrared) Spectrophotometry in the infrared region, usually for the purpose of chemical analysis through measurement of absorption spectra associated with rotational and vibrational energy levels of molecules. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)