^(182)Hf实验室参考标准的研制与加速器质谱测量

Preparation of ^(182)Hf AMS Standard Sample and Test on HI-13 Tandem AMS

介绍了用于HI-13串列加速器质谱(AMS)测量的^(182)Hf实验室参考标准的研制.通过^(180)Hf的连续热中子俘获产生^(180)Hf,用热电离质谱对初始参考标准的同位素比进行了精确测量.取一定量的初始参考标准,加入已知量的稳定同位素(^(180)Hf)作为稀释剂,通过逐级稀释的方法,最终得到同位素比从10^(-6)—10^(-10)的一系列参考标准.并对该系列参考标准进行了AMS测量,结果显示^(182)Hf/^(180)Hf的测量值与标称值呈良好的线性关系,说明该AMS系统可以准确测量同位素比在10^(-6)—10^(-10)范围内的样品.

The preparation and accelerator mass spectrometry （AMS） measurements of a series of ^182Hf AMS calibration standards are described in this paper. The preparation consists of five processes, the synthesis of the initial ^182Hf/^180Hf standard sample by double neutron capture reaction of ^180Hf, the accurate measurement of this standard for isotopic ratio with thermal ionization mass spectrometry （TIMS）, the chemical separation of isobaric interference ^182w, the sequential dilution of the initial standard, and the preparation of HfF4. The value of ^182Hf/^180Hf in the initial ^1822Hf/^180Hf standard was obtained with TIMS to be （1.63±0.01）×10^-6. Chemical separation and purification procedures were developed and applied in the preparation of all ^182Hf/^180Hf standards for the removal of major isobaric interference nuclide ^182w. As a result, three ^182Hf AMS standards with ^182Hf /^180Hf ratios of （1.63±0.01）×10^-6 , （3.22±0.26）× 10^-8, （3.45±0.32）×10^-10 were obtained. AMS measurements of these standard samples were performed and good linearity was obtained in a plot of AMS results vs nominal values for ^182Hf/^180Hf ranging from 1.63×10^-6 to 3.45 × 10^-10.