Thallium bromoiodide / thallium bromide iodide () and thallium bromochloride / thallium bromide chloride () are mixed salts of thallium(I) that are used in spectroscopy as an optical material for transmission, refraction, and focusing of infrared radiation. The materials were first grown by R. Koops in the laboratory of Olexander Smakula at the Carl Zeiss Optical Works, Jena in 1941.
Thallium(I) bromoiodate / thallium(I) bromide iodate () and thallium(I) bromochlorate / thallium(I) bromide chlorate () are thallium(I) compounds utilized as infrared optics for the transmission, refraction, and focusing of infrared radiation. These materials were initially developed by R. Koops in the laboratory of Olexander Smakula at Carl Zeiss Optical Works, Jena in 1941.