GRATING LIGHT-REFLECTION SPECTROSCOPY OF COLLOIDS AND SUSPENSIONS

The interaction of light with scattering matrixes, particularly partic les suspended in a liquid, is described as it relates to the use of a technique known as grating light reflection spectroscopy (GLRS). Analy sis of the singular behavior of light reflected from a transmission di ffraction grating in contact with a scattering matrix has shown that t he effective dielectric function of the medium in contact with the gra ting can be measured using a reflection method. The relative contribut ions of the real and imaginary components of the effective dielectric function are probed as mean particle radius increases, shifting the fo rward scattering regime from the Rayleigh limit to the Fraunhofer diff raction approximation. It is shown that GLRS provides substantial info rmation regarding the characteristics of colloids and suspensions. Fur ther investigations could, in theory, yield particle shape and density distribution information as well.