Used in infrared spectroscopy as a beam splitter due to its high transparency in the infrared region. Commonly employed in optical components for far-infrared applications, including windows and lenses in specialized instruments such as spectrometers and thermal imaging devices. Also utilized in scintillation counters for radiation detection because of its ability to emit light when exposed to ionizing radiation. Serves as a source of caesium ions in research and development of photoelectric materials and certain types of catalysts.