Infrared spectroscopy resembles Raman spectroscopy in that it provides information on the vibrational and rotational energy levels of a spccics, but it differs from the latter technique in that it is based on studying the light transmitted through a medium after absorption, and not that scattered by it.
The techniques of Raman and IR spectroscopy arc generally considered complementary in the gas and solid phases bccausc some of the spccics under study may reveal themselves in only one of the techniques. Nevertheless, it must be stressed that Raman scattering is not affcctcd by the aqueous medium, whereas strong absorption in the infrared shown by water proves to be a troublesome interfering factor in the study of aqueous solutions by the IR method.
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