Attenuated Total Reflection

Attenuated Total Reflection (ATR) is a spectroscopic technique used to analyze thin films and surface layers on reflective substrates. In ATR, infrared radiation is directed into a crystal with a high refractive index, creating an evanescent wave that penetrates a small distance into the sample in contact with the crystal surface. This allows for the measurement of the absorption of infrared radiation by the thin film or surface layer, providing information about its composition and thickness. This method is particularly useful for studying samples that are difficult to analyze using conventional transmission methods.