title: Absolute isotopic composition and atomic weight of neodymium using thermal ionization mass spectrometry.
abstract: 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.%) 142Nd, 12.173(18) at.% 143Nd, 23.798(12) at.% 144Nd, 8.293(7) at.% 145Nd, 17.189(17) at.% 146Nd, 5.756(8) at.% 148Nd, and 5.638(9) at.% 150Nd, 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.
authors.affiliation: National Research Centre for Certified Reference Materials, Beijing 100013, China. motian_zhao@263.net.cn
authors.forename: Motian
authors.initials: M
authors.lastname: Zhao
authors.forename: Tao
authors.initials: T
authors.lastname: Zhou
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Hai
authors.initials: H
authors.lastname: Lu
authors.forename: Xiang
authors.initials: X
authors.lastname: Fang
authors.forename: Chunhua
authors.initials: C
authors.lastname: Guo
authors.forename: Qiuli
authors.initials: Q
authors.lastname: Li
authors.forename: Chaofeng
authors.initials: C
authors.lastname: Li
mesh_terms: D006358:Hot Temperature; D038622:Internationality; D007554:Isotopes / Q000032:analysis* / Q000592:standards*; D008970:Molecular Weight; D009354:Neodymium / Q000032:analysis* / Q000592:standards*; D012016:Reference Values; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods* / Q000592:standards*
chemical_list: D007554:Isotopes; D009354:Neodymium