Optical constants of carbons and coals in the infrared

Abstract A plane polarised light reflection technique has been used to measure the refractive and absorption indices of a series of carbons in the wavelength region one to ten microns at room temperature. The samples used consisted of coals and compressed soots, of various carbon contents, and a pyrographite. The tendency for materials of higher carbon content to have higher values of absorption and refractive indices, previously observed in the visible and u.v. region, is continued in the i.r.