Arsenic triselenide
Arsenic triselenide is an inorganic chemical compound with the chemical formula.
Amorphous arsenic triselenide is used as a chalcogenide glass for infrared optics. When purified, it transmits light with wavelengths between ca. 0.7 and 19 μm.
In arsenic triselenide, arsenic is covalently bonded to selenium, where arsenic has a formal oxidation state of +3, and selenium −2.