... A laboratory approach to the interstellar sulfide problem. ... Optical constants: . ... The sulfides were synthesized from the native elements by the evacuated silica tube method with an annealing at 1273 K. The resulting sulfide powders were portioned, pressed to pellets, and melted in an arc furnace. The molten samples were quenched. For samples with x=0.0, 0.1, 0.25, 0.4, 0.5, 0.6, 0.75, 0.9, reflectance by polished surfaces was measured in the range from 2 to 500 microns. ...