Research On The Application Of EDiX-â…¢ X-ray Tube In Energy Dispersive X-Ray Fluorescence Analysis

X-ray tube is one of the most important excitation sources in energy dispersive X-ray fluorescence analysis,which was mostly used for laboratory analysis in the past years.Isotope excitation source is commonly adopted in the portable X-ray fluorescence analyzer and the in-situ X-ray fluorescence analysis.With the development of miniature X-ray tube manufacturing level and its commercialization, X-ray tube for its unique advantages has added new vigor to the field energy dispersive X-ray fluorescence analysis technology.This paper originated from the 863 national project—"The development of the submarine in-situ X-ray probe analysis system"(No.2006AA09Z219).Based on the miniature X-ray tube used as the excitation source,this paper aims at establishing the basic equation of the energy dispersive X-ray fluorescence analysis,and through theoretical and experimental analysis summing up the optimum parameters under different conditions,Thus providing a scientific basis for the development of energy dispersion x-ray fluorescence spectrometer,reducing the detection limit and improving the accuracy of analysis.In this paper,the application problem of EDiX-ШX-ray tube in energy dispersive X-ray fluorescence analysis was in-depth studied.The main research results including:1)Based on the continuous energy X-ray excitation,establishing the basic equation of the energy dispersive X-ray fluorescence analysis.2)Establishing the best geometric parameters among the X-ray tube,sample and detector(referred to as "tube-sample-detector").When using EDiX-ШX-ray tube and XR-100CR Si-PIN detector(14mm² sensitive area and 500μm thickness), the range of incident angle is 70°～75°,the range of emergence angle is 70°～75°,the distance of X-ray tube and sample is 11～12mm,the distance of detector and sample is 10～11 mm.for probe design,the best geometric parameters are provided.3)Through theoretical analysis and experimental data processing,the following conclusion is that,when the current fixed at 1.125μA,the voltage changes within 0～40 kV,the total area of feature peak increases with the increase of voltage and the peak to background ration increases and then decreases,the area slowly increase in the larger voltage.When the voltage is the best excitation voltage,the scope of the current is 0～50uA,with the increase of current,the total area of feature peak increases and then decreases and the peak to background ration decreases.4)On the basis of the experiment,establishing the mathematical model of the best excitation voltage,there is the positive linear correlation between this voltage and element detection(or atomic number).5)Based on X-ray tube excitation,the detection limit is 1.3ug/g in Cu,1.4ug/g in As,5.3ug/g in Pb,which improves 4 to 10 times than ²³⁸Pu source.6)By measuring 26 geochemistry standard samples,the qualified rate is 92.3% in Ti,85%in Mn and 100%in Fe,the accuracy is 5.67%,4.32%and 1.13%. Research results also successfully extended to the alloy analysis and RoHS command detection,for nickel-iron alloy samples,the analytical error of Fe and Ni is less than 0.17%and 0.21%,the accuracy is 0.94%in Fe and 1.02%in Ni.For Br in the polyethylene,the average relative error is 4.9%,the accuracy is 2.51%.