Reflectance spectroscopy explores how surface-reflected radiation varies with angle and the incident radiation's composition. Two key types are regular (specular) and diffuse reflection, each requiring distinct methods for analysis. The first method uses the Fresnel equations to derive optical constants from regular reflection, while recent modifications improve accuracy by adjusting the phase boundary conditions. Additionally, total reflection occurs under specific angles when a sample does not absorb radiation, with energy transfer influenced by diffraction at the boundary.
