Absolute isotopic composition and atomic weight of neodymium using thermal ionization mass spectrometry

摘要

Synthetic mixtures prepared gravimetrically from highly enriched isotopes of neodymium in the form of oxides of well-defined purity were used to calibrate a thermal ionization mass spectrometer. A new error analysis was applied to calculate the final uncertainty of the atomic weight value. Measurements on natural neodymium samples yielded an absolute isotopic composition of 27.153(19) atomic percent (at.%) Nd-142, 12.173(18) at.% Nd-143, 23.798(12) at.% Nd-144, 8.293(7) at.% Nd-145, 17.189(17) at.% Nd-146, 5.7,56(8) at.% Nd-148, and 5.638(9) at.% Nd-150, and the atomic weight of neodymium as 144.2415(13), with uncertainties given on the basis of 95% confidence limits. No isotopic fractionation was found in terrestrial neodymium materials. Copyright (C) 2005 John Wiley & Sons, Ltd.