Optical constants of tin monosulphide single crystals in the transparency region

Abstract

The transmittance and reflectance of single crystals of tin monosulphide were measured at normal incidence from which values the absorption coefficient was calculated. The refractive index, n, of a SnS single crystal was measured by the prism method in the transparency region. The extinction coefficient, k, was calculated from the absorption coefficient. Measurements were performed at room temperature using plane-polarised light with the plane of polarisation parallel to either the a or b crystallographic axis, both of which lie in the plane of cleavage. The real and imaginary parts of the complex dielectric constant ( epsilon r, epsilon i) as well as the reflectance and its phase change (R, Phi ) were calculated from the values of n and k. It was shown that the SnS single crystal exhibits birefringence. Assuming that SnS binding is partly ionic and partly covalent, the optical constants were satisfactorily fitted to the model of a single effective oscillator.