Journal of Research of the National Bureau of Standards Section A Physics and Chemistry · 1975 · 60 citations · 8 references
Natural SciencesChemistryAnalytical ChemistryElemental AnalysisInorganic ChemistryElemental Composition AnalysisIsotope SeparationMass Spectrometric Elemental AnalysisMass SpectrometryElemental AbundancesIsotopic Abundance RatiosIsotopic AbundancesIsotopic Ratio DeterminationIsotopic RatiosSiliconSystematic Error AnalysisSystematic Uncertainties
Ab solute va lu es have been obtained for th e isotopic a bund a nce rati os of a re fe re nce sa mpl e of s ilico n us ing e lec tron impa ct mass s pectrom etry. Sa mpl es of known isoto pi c co mpos it ion pre pared fro m nearly isotop ica lly pure se pa rated sili co n isotopes we re used to ca librate th e ma ss s pectrom e te rs. The res ult ing absolute ,sS i/,JOS i ratio = 29.74320 0.00747 and th e 29S i/,,S i ratio = 1. 50598 0.00086 whi c h yield at om pe rcen ts of '"S i = 92.229:n . 0.00155. " 'Si =,1.()6982 I 0.00124 and :lIISi = :). 10085 I 0.00074. The atomic weight ca lc ulated from thi s isotopic co mpos ition is 28.085526 0.000056. Th e indi cated un ce rtainti es are overall limit s of e rror based o n 95 perce nt confidence limit s for th e mea ns a nd a ll owan ces for th e effec ts of kn ow n sources of poss ibl e s yste ma tic e rror. A study of natura l '"S i/,IIIS i rati o variations re ported in th e literature e xtend s tb e es timat ed un ce rt a int y in th e atomic we ight of natural s ili co n to ' 0.000.39.
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