PIXE方法在地质样品测定中实验流程的开发和评价

张建东^{1, 2, 3}，邵拥军^{1, 2}，石山大三³

(1. 中南大学 地球科学与信息物理学院，长沙 410083；
2. 中南大学 有色金属成矿预测教育部重点实验室，长沙 410083；
3. 秋田大学 工学资源学研究院，环境资源研究中心，日本 秋田 010-8502)

摘 要：利用质子荧光分析(PIXE)方法在聚碳酸酯薄膜上测定了日本地质调查局标准岩石和矿石样品的化学组分，样品为细粒、微量的(1~2 mg)粉末地质样品。PIXE测试的结果表明：对标准岩石样品而言，具有0.4 μm孔径薄膜的测定值与其他孔径薄膜(0.2，0.6和0.8 μm)的测定值相比，其相对岩石标样的参考值变化更小，更适合作为理想样靶被采用；对标准矿石样品而言，0.2 μm孔径薄膜的测定值与矿石标样的参考值相比，更适合作为理想的样靶。日本地质调查局标准岩石和矿石样品测定的化学组分总是稍微不同于标准样品的参考值，因此计算了测定值和参考值之间的校正因子，通过校正因子的调整，针对量少的岩石和矿石粉末样品，就可以获得较为精确的测试结果。

关键词：质子荧光分析(PIXE)；过滤薄膜；孔径；校正因子

Development and evaluation of experimental process of PIXE method for geological samples

ZHANG Jian-dong^{1, 2, 3}, SHAO Yong-jun^{1, 2}, ISHIYAM Daizo³

(1. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China;
2. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
Central South University, Changsha 410083, China;
3. Center for Geo-Environmental Science, Graduate School of Engineering and Resource Science,
Akita University, 1-1 Gakuen-Machi, Tegata, Akita 010-8502, Japan)

Abstract:Chemical analyses of fine-grained powder samples from the Geological Survey of Japan (GSJ) trapped on a polycarbonate filter were carried out by particle induced X-ray emission (PIXE) to measure the chemical compositions of geological samples having small amounts (1-2 mg). The variability of results obtained by using a filter with a pore size of 0.4 μm was smaller than the variability of results obtained by using filters with pore sizes of 0.2, 0.6 and 0.8 μm for rock samples. The results obtained by using filter with a pore size of 0.2 μm are better than the results obtained by using filters with pore sizes of 0.4, 0.6 and 0.8 μm for ore samples. The results of chemical analysis of powder samples of Japanese rock standards by PIXE are slightly different from certified values by the Geological Survey of Japan because of self-absorption of characteristic X-rays in measurements. Calibration factors were calculated on the basis of the measured values and certified values. The use of these calibration factors enables accurate results to be obtained for small amounts of powder samples of rocks and ores.

Key words:particle induced X-ray emission (PIXE); membrane filter; pore size; calibration factor