地质样品X射线荧光分析中的背景相关曲线及其应用

Background-Related Curve in the X-Ray Fluorescence Spectrometric Analysis of Geological Materials and Its Application

采用粉末压片-X射线荧光法,测量了水系沉积物、土壤、岩石等国家一级标准物质。对用LiF(200)晶体在20.70°～48.00°衍射角(2θ)得到的X射线背景数据进行了研究。以30.97°和25.70°(2θ)为参考背景角度,进行了背景曲线的幂函数拟合,背景相对强度的拟合回代值与实测值的相对误差小于2.6%,多数小于1%。利用该拟合函数,可以计算出20.70°～48.00°内任意两个角度下的背景比值(背景系数)。因此,实验中可以根据情况选取合适的公共背景角度,并用拟合函数计算各元素谱峰角度处的背景系数。可采用公共背景法的元素数为13个左右,适当延长公共背景点的测量时间,可以降低背景的统计涨落。

32 national geological reference materials namely GBW 07301～07312,GBW 07401～07408,GBW 07103～07114, were measured by Xray fluorescence spectrometry with pressed pellet sample preparation technique. The background data for 2θ angles ranged from 20.70° to 48.00° collected by using LiF (200) crystal were studied. Power function fitting of background was carried out with background intensities measured at angles 30.97° and 25.70°(2θ) as reference background. The relative deviations of the calculated background ratios and the measured ones were within 2.6% while most of them less than 1%.The fitted power function can be used to calculate background ratios(coefficients) of any two angles in the 2θ angle range of 20.70° to 48.00°. Thus common background method can be used conveniently. In this 2θ angle range, about 13 elements can be measured by common background method with high efficiency.