Optical constants of absorbing materials: a new approach.

A detailed study of a new method of determining the optical properties of absorbing materials is presented. It makes use of normal incidence reflectances from the specimen itself (R(s)) and from the specimen coated with a transparent film of two different thicknesses but of the same refractive index (R(1s) and R(2s)) in the form of R(1s)/R(s) and R(2s)/R(s)- It is seen that a simple goniometer can be easily adopted for measuring the reflectance ratios over a wide spectral range. The versatility of the method has been proved by the fact that it has been successfully adopted for specimens with surface structures varying from atomically smooth to rough surfaces.