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An isochron diagram will only give a valid age if all samples are cogenetic, which means they have the same initial isotopic composition (that is, the rocks are from the same unit, the minerals are from the same rock, etc.), all samples have the same initial isotopic composition (at t 0), and the system has remained closed.
Here, R A is the isotope amount ratio of the natural analyte, R A = n(i A) A /n(j A) A, R B is the isotope amount ratio of the isotopically enriched analyte, R B = n(i A) B /n(j A) B, R AB is the isotope amount ratio of the resulting mixture, x(j A) A is the isotopic abundance of the minor isotope in the natural analyte, and x(j A) B is the ...
R l = X w α l/w R w + (1 − X w)α l/s R s, [74] where R l, R w, and R s are the DHRs of lipids, water, and substrates, respectively. X w is the mole fraction of lipid H derived from external water, whereas α l/w and α l/s denote the net isotopic fractionations associated with uptake and utilization of water and substrate hydrogen ...
Stable isotopes partitioning between two substances A and B can be expressed by the use of the isotopic fractionation factor (alpha): α A-B = R A /R B. where R is the ratio of the heavy to light isotope (e.g., 2 H/ 1 H or 18 O/ 16 O). Values for alpha tend to be very close to 1. [1] [2]
Part of the Chart of Nuclides showing some stable or nearly-stable s-, r-, and p-nuclei. The classical, ground-breaking works of Burbidge, Burbidge, Fowler and Hoyle (1957) [1] and of A. G. W. Cameron (1957) [2] showed how the majority of naturally occurring nuclides beyond the element iron can be made in two kinds of neutron capture processes, the s- and the r-process.
Archaeological materials, such as bone, organic residues, hair, or sea shells, can serve as substrates for isotopic analysis. Carbon, nitrogen and zinc isotope ratios are used to investigate the diets of past people; these isotopic systems can be used with others, such as strontium or oxygen, to answer questions about population movements and cultural interactions, such as trade.
A table apportioning the heavy isotopes phenomenologically between s-process and r-process isotopes was published in 1957 in the B 2 FH review paper, [1] which named the r-process and outlined the physics that guides it. [8] Alastair G. W. Cameron also published a smaller study about the r-process in the same year. [9]
In nuclear physics, the island of stability is a predicted set of isotopes of superheavy elements that may have considerably longer half-lives than known isotopes of these elements. It is predicted to appear as an "island" in the chart of nuclides , separated from known stable and long-lived primordial radionuclides .