Polonium-210
210Po is an alpha emitter that has a half-life of 138.376 days; it decays directly to its daughter isotope 206Pb. A milligram of 210Po emits as many alpha particles per second as 5 grams of 226Ra. A few curies (1 curie equals 37 gigabecquerels) of 210Po emit a blue glow which is caused by excitation of surrounding air. A single gram of 210Po generates 140 watts of power. Because it emits many alpha particles, which are stopped within a very short distance in dense media and release their energy, 210Po has been used as a lightweight heat source to power thermoelectric cells in artificial satellites; for instance, 210Po heat source was also used in each of the Lunokhod rovers deployed on the surface of the Moon, to keep their internal components warm during the lunar nights. Some anti-static brushes contain up to 500 microcuries of 210Po as a source of charged particles for neutralizing static electricity in materials like photographic film. 210Po was used to kill Russian dissident and ex-FSB officer Alexander V. Litvinenko in 2006 and has recently been suspected as a possible cause of Yasser Arafat's death. 210Po is also used in initiators for atomic bombs.
The majority of the time 210Po decays by emission of an alpha particle only, not by emission of an alpha particle and a gamma ray. About one in 100,000 decays results in the emission of a gamma ray. This low gamma ray production rate makes it more difficult to find and identify this isotope. Rather than gamma ray spectroscopy, alpha spectroscopy is the best method of measuring this isotope.
210Po occurs in minute amounts in nature, where it is an intermediate isotope in the radium series (also known as the uranium series) decay chain. It is generated via beta decay from 210Bi.
Read more about this topic: Isotopes Of Polonium