Attenuated Total Reflectance

Crystal Interface

Pressure applied to the sample ensures the substrate makes uniform contact with the high refractive index crystal. In the study of attenuated total reflectance, a mechanical clamp holds the paper against materials like diamond or zinc selenide. Even small air gaps between the paper and the crystal surface lead to poor signal intensity.

Signal Quality

Absorption of energy at specific wavelengths identifies the binders and pigments present on a printed sheet. Since attenuated total reflectance measures only the immediate surface, it identifies contaminants or moisture barriers on a multi layer board. Variations in the depth of penetration occur based on the angle of incidence and the wavelength of the light, which allows for some control over the volume of material sampled.

Proper calibration against a known standard ensures that the resulting peaks correspond to the actual chemical composition of the coating.