| The paper topic selection comes from two aspects:one is the field about resources and environment and technology in State863Projects,named "Development of high-precision spectrum detecting instrument (project no.2012AA061803)",the other belongs to China Geological Survey, called " Development of Submarine in Situ X-ray Fluorescence Detection System". In the exploration of Marine mineral resources,Submarine in Situ X-ray Fluorescence Detection System can be used to determine the contention of elements in seafloor sediments real-Time, then quickly find Marine mineral resources and make evaluation. In the instrument spectral line of Submarine in Situ X-ray Fluorescence Detection System, because the full-energy peak of multi-element characteristic X ray interference each other and primary X-ray is scattered by sea-water, the background of full-energy peak of characteristic X ray in target element is magnified obviously.Therefore, rejecting the scattering background of full-energy peak effectively is a critical technology guarantee to mprove the degree of accuracy of Submarine in Situ X-ray Fluorescence Analysis. On the basis of discuss a great number of classical methods for example Tap method,and Covell method,and Wason method and so on, according to the characteristics of submarine in-situ X-ray fluorescence spectrum, the paper elaborate in detail applied research on Submarine in Situ X-ray Fluorescence spectrum by using several curve fitting methods such as Fourier transform method, Snip method, Polynomial fitting method,and achieve remarkable results, embodied in the following respects:1. The matlab programming by using Fourier transform method is better to describ the accually shape of spectrum line measued,and Snip method is better to reach a certain effection of background rejection,and the cubic polynomial fitting method is not only to reject scattering background effectively,but also remain the shape of feature peak,making it not change.2. by using Fourier transform method, and Snip method, and Polynomial fitting method,we selected10samples for measurement and analysis and rejected the background of iron element in energy spectrum.At last,we obtained the linearity of using the three methods fitting, and results showed that the fitting linearity was only0.89before background rejection.The ultimal data of linearity of global fitting was0.9937,by fitting the value between the data by using Fourier transform method and the standard contention,while the Snip method was0.9888and Polynomial fitting method was0.9966. By contrasting, Polynomial curve fitting method is better to suitable for required accuracy of Submarine in Situ X-ray Fluorescence Detection System.3.By using Polynomial curve fitting method to reject the background in Submarine in Situ X-ray Fluorescence Detection System,we conduct two probing tests, Separately Carries On in lakebeds and the shallow sea.In lakebeds test, contrating using the WDXRF analysis, the Relative error is within15%with Submarine in Situ X-ray Fluorescence Detection System in detecting the contention of iron in the samples of Bottom sediment, in addion, the actual contention of iron in the lakebed is between2.9%and7%, which basically match the analysis results the contention of iron in lake sediments samples,meeting the accuracy requirements of Submarine in Situ X-ray Fluorescence Detection System.In shallow sea test,by using X-ray Fluorescence Detection System to conduct the fixed-point measurement and real-time tracking measurement in the same measuring line, the test data is processed by the Background estimation method of polynomial curves to reject the background,which changes between1～3.5%,having exactly the same contention of iron in Shallow submarine sediments.All these reach a conclusion that Polynomial curve fitting method to reject the background can be used on the bottom of the in situ X fluorescence analysis, and has initially achieved good application effect. |
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