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Sulfur (16 S) has 23 known isotopes with mass numbers ranging from 27 to 49, four of which are stable: 32 S (95.02%), 33 S (0.75%), 34 S (4.21%), and 36 S (0.02%). The preponderance of sulfur-32 is explained by its production from carbon-12 plus successive fusion capture of five helium-4 nuclei, in the so-called alpha process of exploding type II supernovas (see silicon burning).
However, troilite from the Canyon Diablo meteorite was later discovered to have variable sulfur isotope composition. [12] As a result, VCDT was established as a hypothetical sulfur isotope reference with a 34 R value of 0.044151 [11] and δ 34 S of 0‰, but no physical sample of VCDT exists.
Of the 25 known isotopes of sulfur, four are stable. [1] In order of their abundance, those isotopes are 32 S (94.93%), 34 S (4.29%), 33 S (0.76%), and 36 S (0.02%). [2] The δ 34 S value refers to a measure of the ratio of the two most common stable sulfur isotopes, 34 S: 32 S, as measured in a sample against that same ratio as measured in a known reference standard.
Other stable sulfur isotopes are produced in the bypass processes related with 34 Ar, and their composition depends on a type of a stellar explosion. For example, proportionally more 33 S comes from novae than from supernovae. [30] On the planet Earth the sulfur isotopic composition was determined by the Sun.
Isotope geochemistry is an aspect of geology based upon the study of natural variations in the relative abundances of isotopes of various elements. Variations in isotopic abundance are measured by isotope-ratio mass spectrometry , and can reveal information about the ages and origins of rock, air or water bodies, or processes of mixing between ...
The δ values and absolute isotope ratios of common reference materials are summarized in Table 1 and described in more detail below. Alternative values for the absolute isotopic ratios of reference materials, differing only modestly from those in Table 1, are presented in Table 2.5 of Sharp (2007) [1] (a text freely available online), as well as Table 1 of the 1993 IAEA report on isotopic ...
It contains a table of main isotopes and eventually the standard atomic weight. This template is reused in {{Infobox <element>}} as a child Infobox (|child=yes). As of Jan 2023, a 'Main isotope' is conforming MOS:MAINISOTOPE (under construction, see WP:ELEMENTS What is a "Main_isotope"?) Each isotope has its own row, with decay modes:
Measurement of natural variations in the abundances of stable isotopes of the same element is normally referred to as stable isotope analysis. This field is of interest because the differences in mass between different isotopes leads to isotope fractionation, causing measurable effects on the isotopic composition of samples, characteristic of their biological or physical history.