Absolute isotopic abundance ratios and the atomic weight of a reference sample of chromium

Abstract

Ab so lut e va lu es have been obta in e d for th e iso topi c ab und a nce ratios of a re fe re nce sa mpl e of chromium. us ing s urface e mi ss ion ma ss s pec trom e try. Sa mpl es of known isotopi c compos ition , vrepa re d I rom nea rl y pure se parated c hromium isotop es, were use d to c alibrat e t he mass s pec l rom e tno. Th e res ulting ab solute valu es are C r 5 0/C,-5' = 0.051859 ± 0.000100, Cr'''/C r'' = 0.11 3386 ·± 0.000145 , C r"/C r52 = 0 .028222 ± 0 .000059, yie lding a n atomic we ig ht (C '2= 12) of 51.99612 ± 0.00033. The indi ca ted un ce rt a inties arE' overall limit s of e rro r bas ed on 95 pe rc e nt confidence limit s for th e nwa n and a llo wa nces for e ffec ts of k nown ::io UIT('S uf po ss ibl e sys tl'mali c (' ITOr. Ke y Word s : C hromium. a tomi c w(·ight. is otopi c a bund a nces. absolut e ratios.