薄膜法X射线荧光测量中样品检测位置及防护铅板内衬材料的选择研究

The Study of Selecting Sample Detecting Position and Lead Plate Inner Material in Thin Film Method X-Ray Fluorescence Measurement

(1)以型号316不锈钢金属板为研究对象,对薄膜法X射线荧光光谱测量中,样品检测位置的选择进行研究,确定了最佳的样品检测位置为样品距离X射线管和探测器水平基线1cm处,并且与X射线管和探测器水平基线成16°角度。(2)以工业环境空气重金属污染物Pb,Cd,Cr为主要分析对象,在有铅板防护情况下进行薄膜法X射线荧光光谱测量研究,发现X射线会穿透样品薄膜而继续激发防护铅板,使得滤膜背景光谱中有较强的铅谱线干扰,会对实际样品中铅元素的测量产生影响。在薄样和防护铅板之间加上一层隔离材料,可有效避免防护铅板中铅谱线对样品测量产生的干扰。(3)以型号316不锈钢、黄铜、铝材、紫铜和聚四氟乙烯几种硬质隔离材料作为铅板内衬材料进行选择研究,结果表明:紫铜的X射线荧光光谱中所含元素的谱线最少,谱图中没有出现重金属Cr,Cd,Pb的谱峰,并且能量较高部分靶材散射光谱强度较弱,对实际样品中重金属元素Cr,Cd和Pb的测量不会产生干扰,作为铅板的内衬金属材料可以避免防护铅板中铅元素谱线的干扰,是最佳的薄膜法X射线荧光光谱分析中铅板的内衬金属材料。该研究为组装及搭建便携式大气及水体重金属X射线荧光光谱分析仪提供了重要的理论依据。

（1） In this paper type 316 stainless steel metal plate as the research object ,the selection of sample detecting position was studied when thin film method X-ray fluorescence measurement was conducted .The study showed that the optimal location for the sample detection was sample distance X-ray tube and detector baseline 1cm with the baseline into a 16＆#176;angle .（2） Heavy metal pollutants of Pb ,Cd and Cr in industrial ambient air as the main analysis object ,when thin film method X-ray fluorescence conducted with lead plate protection ,X-rays will penetrate the membrane and continuely stimulate the protective lead plate . Therefore there is lead spectral line interference in the filter membrane background spectrum ,which will affect the detection of lead element in real samples .Studies show that when a layer of isolating material was applied between the thin sample and the protective lead plate ,the interference of lead line can effectively be avoided .（3） Several rigid insulating material of type 316 stainless steel ,brass ,aluminum ,red copper and PTEE as lead inner material were selected and studied .The study results showed that compared with X-ray fluorescence spectra of other lead inner materials ,the X-ray fluorescence spectrum of red cop-per contained the least element spectral lines .There were not Cr ,Cd and Pb spectrum peaks in the X-ray fluorescence spectrum of red copper .And the target timber scattering spectrum intensity in the high energy part was weaker compared to other X-ray fluorescence spectrum .The above analysis shows that red copper has the minimal disturbance to the actual measurement of heavy metals Cr ,Cd and Pb .At the same time ,red copper as lead inner materials can effectively avoid the interference of lead spec-trum line in lead plate .So red copper is the best lead plate inner materials in thin film method X-ray fluorescence spectroscopy measurement .This study provides an important theoretical basis for the assembling and setting up air and water weight metal X-ray fluorescence spectrometer .