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Thulium-170 has a binding energy of 8 105.5144(43) keV per nucleon and a half-life of 128.6 ± 0.3 d.It decays by β − decay to 170 Yb about 99.869% of the time, and by electron capture to 170 Er about 0.131% of the time. [1]
Radioactive isotope table "lists ALL radioactive nuclei with a half-life greater than 1000 years", incorporated in the list above. The NUBASE2020 evaluation of nuclear physics properties F.G. Kondev et al. 2021 Chinese Phys. C 45 030001. The PDF of this article lists the half-lives of all known radioactives nuclides.
Naturally occurring thulium (69 Tm) is composed of one stable isotope, 169 Tm (100% natural abundance).Thirty-nine radioisotopes have been characterized, with the most stable being 171 Tm with a half-life of 1.92 years, 170 Tm with a half-life of 128.6 days, 168 Tm with a half-life of 93.1 days, and 167 Tm with a half-life of 9.25 days.
Thulium-169 is thulium's only primordial isotope and is the only isotope of thulium that is thought to be stable; it is predicted to undergo alpha decay to holmium-165 with a very long half-life. [ 10 ] [ 22 ] The longest-lived radioisotopes are thulium-171, which has a half-life of 1.92 years, and thulium-170 , which has a half-life of 128.6 days.
For example, the medical sciences refer to the biological half-life of drugs and other chemicals in the human body. The converse of half-life (in exponential growth) is doubling time. The original term, half-life period, dating to Ernest Rutherford's discovery of the principle in 1907, was shortened to half-life in the early 1950s. [1]
Absorption half-life 1 h, elimination half-life 12 h. Biological half-life ( elimination half-life , pharmacological half-life ) is the time taken for concentration of a biological substance (such as a medication ) to decrease from its maximum concentration ( C max ) to half of C max in the blood plasma .
When radionuclides are used pharmacologically, for example in radiation therapy, they are eliminated through a combination of radioactive decay and biological excretion.An effective half-life of the drug will involve a decay constant that represents the sum of the biological and physical decay constants, as in the formula:
^^ Bismuth-209 was long believed to be stable, due to its half-life of 2.01×10 19 years, which is more than a billion times the age of the universe. § Europium-151 and samarium-147 are primordial nuclides with very long half-lives of 4.62×10 18 years and 1.066×10 11 years, respectively.