infrared reflectance spectroscopy attenuated total reflectance infrared spectroscopy multiple internal reflection spectroscopy MIRS ATR-IR spectrometry FIX:0000653 ATR/IRS internal reflection spectrometry attenuated total reflectance spectrometry attenuated total reflectance infra-red spectroscopy Spectroscopy where infrared light is introduced into a prism at an angle exceeding the critical angle for internal reflection. This produces an evanescent wave at the reflecting surface (a surface which is transparent to infrared such as thallium bromide) on which the sample is supported, and the distortion of the evanescent wave by the sample is measured. ATR-IR ATR spectroscopy multiple internal reflection spectrometry ATR-IR spectroscopy ATR/IR CHMO:0000648 IRS ATR spectrometry internal reflection spectroscopy