Consider ATR sampling using a trapezoidal ZnSe crystal. In the mid-infrared region, refractive indices for ZnSe and water are approximately 2.4 and 1.3, respectively. What is the penetration depth (um) for IR radiation of 1600 cm-1 if it strikes this interface at an angle 10o greater than 33?
Assuming the multiple internal reflections depicted below, what is the effective path length (um) for measurements in which the sample completely covers the crystal's upper face?