The role of cesium

Cesium is used in atomic clocks, which are incredibly accurate. NIST-F1, America's primary time and frequency standard, is a cesium fountain atomic clock developed at the NIST laboratories in Boulder, Colorado. NIST-F1 contributes to the international group of atomic clocks that define Coordinated Universal Time (UTC), the official world time. As scientists continue to improve its technology, uncertainty in NIST-F1's measurement of time is continually improving. Currently it neither gains nor loses as much a second in more than 60 million years - but see strontium. Cesium is also used in photoelectric cells and as a catalyst in the hydrogenation of organic compounds. The metal is used as a 'getter' in vacuum tubes. Cesium hydroxide is used to etch silicon.