FTIR methods are related to the techniques of RAIRS and IRAS. These methods are sensitive to the vibrational modes of
molecules in the gas phase or attached to a surface.
- Attenuated Total Reflectance (ATR)
With the ATR technique, the infra red beam samples a surface by internal reflection of the light. The molecule of interest is placed on the surface, and the infra red light penetrates the surface via the evanescent field.
- Multiple Internal Reflection (MIR)
The MIR approach can enhance the ATR technique by bouncing the light off the surface several times.
- Diffuse Reflectance Infra-red Fourier Transform (DRIFT)
Diffuse Reflectance occurs when light impinges on the surface of a material and is partially reflected and transmitted. Light that passes into the material may be absorbed or reflected out again. Hence, the radiation that reflects from an absorbing material is composed of surface-reflected and bulk re-emitted components, which summed are the diffuse reflectance of the sample
