Radiogenic atoms

On the other hand, the concentration of stable decay products, such as He, Pb, 208pb 207p 5 40(daughter of and Sr (daughter of Rb), increases continuously with time. If one stable atom (subscript 2) is formed per radioactive decay of the mother nuclide (subscript 1), the number of stable radiogenic atoms is... 

The other side of radioactive decay is radiogenic growth. As the parent decays away, the number of atoms of the daughter increases. Let D denote the number of daughter atoms (note that D is not diffusivity here), then D grows as... 

The number of radiogenic daughter atoms formed, G, equals the number of parent atoms consumed ... 

Equation (8.5) gives the number of stable radiogenic daughter atoms ( > ) at any time t formed by decay of a radioactive parent whose initial abundance at / - 0 was N0. 

On the assumption that the radioactive parent atom produces a stable radiogenic daughter (D ), that is zero at t = 0, we can describe the number of daughter atoms at any time with the following equation ... 

Figure 7.1 Hypothetical decay of a radionuclide (N) to a stable radiogenic daughter (D y, the successive loss of atoms of N from radioactive decay are followed by proportional increase in the daughter atoms. (Modified from Faure, 1986.)...

L. R. Stief, and T. W. Stern Radiogenic lead in nonradioactive minerals a due in the search for uranium and thorium. Proc. United Nations Second Intern. Conf. on Peaceful Uses of Atomic Energy. Geneva, Vol. 2, P/773, 215 (1958). 

The radioactive decay of uranium and thorium results in the formation of a series of isotopes that are radiogenic by themselves and keep disintegrating into stable lead isotopes. These radioactive disintegrations are accompanied by the emissions of 4He atoms. Three such radioactive series exist ... 

Isotopic Ratios of Common, Equal Atom and Radiogenic Lead Isotopic Standards, J. Res. Natl. Bur. Stand. Sec. A (1968) 72A, 261-267. 

Ar and a measured quantity of Ar (>99% enriched) is added (method of isotope dilution). After purification, the isotope ratios " Ar Ar and Ar Ar are measured by means of MS. From the isotope ratios " Ar Ar and Ari Ar in the added sample and in the air, the number of radiogenic Ar atoms is calculated. The concentration of K in the sample is determined independently by the usual analytical methods. The main problem with the " K/" Ar method is the possibility that some " °Ar may have escaped or that additional amounts of Ar may have entered the system in the course of time. 

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