Isotopes of sulfur
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Sulfur (16S) has 24 known isotopes with mass numbers ranging from 26 to 49, four of which are stable: 32S (95.02%), 33S (0.75%), 34S (4.21%), and 36S (0.02%). The preponderance of sulfur-32 is explained by its production from carbon-12 plus successive fusion capture of five helium nuclei, in the so-called alpha process of exploding type II supernovas (see silicon burning).
34S abundances vary greatly (between 3.96 and 4.77 percent) in natural samples.
|Standard atomic weight Ar, standard(S)|
Other than 35S, the radioactive isotopes of sulfur are all comparatively short-lived. 35S is formed from cosmic ray spallation of 40Ar in the atmosphere. It has a half-life of 87 days. The next longest-lived radioisotope is sulfur-38, with a half-life of 17 minutes. The shortest-lived is 49S, with a half-life shorter than 200 nanoseconds.
When sulfide minerals are precipitated, isotopic equilibration among solids and liquid may cause small differences in the δS-34 values of co-genetic minerals. The differences between minerals can be used to estimate the temperature of equilibration. The δC-13 and δS-34 of coexisting carbonates and sulfides can be used to determine the pH and oxygen fugacity of the ore-bearing fluid during ore formation.
In most forest ecosystems, sulfate is derived mostly from the atmosphere; weathering of ore minerals and evaporites also contribute some sulfur. Sulfur with a distinctive isotopic composition has been used to identify pollution sources, and enriched sulfur has been added as a tracer in hydrologic studies. Differences in the natural abundances can also be used in systems where there is sufficient variation in the 34S of ecosystem components. Rocky Mountain lakes thought to be dominated by atmospheric sources of sulfate have been found to have different δS-34 values from oceans believed to be dominated by watershed sources of sulfate.
List of isotopesEdit
isotopic mass (u)
|range of natural|
|27S[n 2]||16||11||27.01883(22)#||15.5(15) ms||β+ (98.0%)||27P||(5/2+)|
|β+, 2p (2.0%)||25Al|
|β+, p (<.1%)||26Si|
|28S||16||12||28.00437(17)||125(10) ms||β+ (79.3%)||28P||0+|
|β+, p (20.7%)||27Si|
|29S||16||13||28.99661(5)||187(4) ms||β+ (53.6%)||29P||5/2+|
|β+, p (46.4%)||28Si|
|35S||16||19||34.96903216(11)||87.51(12) d||β−||35Cl||3/2+||Trace[n 4]|
|41S||16||25||40.97958(13)||1.99(5) s||β− (>99.9%)||41Cl||(7/2−)#|
|β−, n (<.1%)||40Cl|
|42S||16||26||41.98102(13)||1.013(15) s||β− (96%)||42Cl||0+|
|β−, n (4%)||41Cl|
|43S||16||27||42.98715(22)||260(15) ms||β− (60%)||43Cl||3/2−#|
|β−, n (40%)||42Cl|
|43mS||319(5) keV||480(50) ns||(7/2−)|
|44S||16||28||43.99021(42)||100(1) ms||β− (82%)||44Cl||0+|
|β−, n (18%)||43Cl|
|45S||16||29||44.99651(187)||68(2) ms||β−, n (54%)||44Cl||3/2−#|
- The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
- Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
- Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.
- Abundance updated from Nubase data.
- Isotope masses from:
- Isotopic compositions and standard atomic masses from:
- de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
- Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
- Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
- National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
- Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.