Arsenic triselenide 三硒化二砷
Arsenic triselenide (As2Se3) is an inorganic chemical compound, a selenide of arsenic.
Amorphous arsenic triselenide is used as a chalcogenide glass for infrared optics, as it transmits light with wavelengths between 870 nm and 17.2 µm.
Arsenic triselenide is covalently bonded. Even so, the arsenic has a formal oxidation state of +3.