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In this situation it is generally uncommon to talk about half-life in the first place, but sometimes people will describe the decay in terms of its "first half-life", "second half-life", etc., where the first half-life is defined as the time required for decay from the initial value to 50%, the second half-life is from 50% to 25%, and so on.
This is a list of radioactive nuclides (sometimes also called isotopes), ordered by half-life from shortest to longest, in seconds, minutes, hours, days and years. Current methods make it difficult to measure half-lives between approximately 10 −19 and 10 −10 seconds.
Download as PDF; Printable version; ... half-life (t 1/2) mode ... Half-life, spin, and isomer data selected from the following sources.
The longest-lived radioactive isotopes are 33 P with a half-life of 25.34 days and 32 P with a half-life of 14.268 days. [3] [4] All others have half-lives of under 2.5 minutes, most under a second. The least stable known isotope is 47 P, with a half-life of 2 milliseconds.
Again, a key feature of using radioactivity in life science applications is that it is a quantitative technique, so PET/SPECT not only reveals where a radiolabelled molecule is but how much is there. Radiobiology (also known as radiation biology) is a field of clinical and basic medical sciences that involves the study of the action of ...
The most stable of them is astatine-202m1, [c] which has a half-life of about 3 minutes; this is longer than those of all ground states except those of isotopes 203–211 and 220. The least stable one is astatine-214m1; its half-life of 265 ns is shorter than those of all ground states except that of astatine-213. [5]
Cell color denotes the half-life of each nuclide; if a border is present, its color indicates the half-life of the most stable nuclear isomer. In graphical browsers, each nuclide also has a tool tip indicating its half-life. Each color represents a certain range of length of half-life, and the color of the border indicates the half-life of its ...
The longest-lived radioisotopes are 194 Hg with a half-life of 444 years, and 203 Hg with a half-life of 46.612 days. Most of the remaining 40 radioisotopes have half-lives that are less than a day. 199 Hg and 201 Hg are the most often studied NMR -active nuclei, having spin quantum numbers of 1/2 and 3/2 respectively.