热电离质谱法超高精度测定^(142)Nd/^(144)Nd同位素比

Ultra-high Precision Determination of ^(142)Nd/^(144)Nd Ratio Using Thermal Ionization Mass Spectrometry

142Nd/144Nd比值的超高精度测定技术对于研究太阳系早期演化及月球-地球早期硅酸盐分异具有重要应用价值。本实验利用热电离质谱(TIMS)开展142Nd/144Nd比值的超高精度测试研究,并对比了动态多接收和静态多接收两种测量方式。结果表明,动态模式具有更高的准确度和精密度。讨论了影响测试精度的各种因素,在此基础上通过优化测试条件,对国际标准(Jndi-1)的142Nd/144Nd测试结果为1.1418348,外部精度优于5×10-6(2SD),完全满足146Sm-142Nd体系研究的技术要求。

Ultra-high precision determination of 142Nd/144Nd ratio has important application value for the research of early evolution of the Solar system and early silicate differentiation of the Earth and the Moon.We utilize thermal ionization mass spectrometry （TIMS） to perform ultra-high precision determination of 142Nd/144Nd in the first time in China and compare both multi-dynamic mode and multi-static mode.The results show that multi-dynamic mode is much higher accuracy and precision than multi-static mode.All influencing factors on the determination were discussed and optimized.142Nd/144Nd isotopic ratio of international standard Jndi-1,whose external precision is better than 5×10^-6 （2SD）,is 1.1418348 and the precision is completely satisfied to technical requirements of 146Sm-142Nd system.