COMPARISON OF SEVERAL BACKGROUND COMPENSATION METHODS USEFUL FOR EVALUATION OF ENERGY-DISPERSIVE X-RAY-FLUORESCENCE SPECTRA

A number of background estimation and modelling strategies suitable fo r evaluating energy-dispersive X-ray spectra by means of non-linear le ast squares fitting are evaluated and intercompared. As background mod elling functions, exponential and linear combinations of mutually orth ogonal polynomials are considered. These functions allow the shape of the background to be determined together with the photopeak intensitie s. As background estimation algorithms, an iterative stripping algorit hm and a background channel selection procedure which is also based on the use of orthogonal polynomials are studied. The last two methods c alculate the spectral background prior to the actual fitting process. For the intercomparison, the various methods were incorporated in the software package AXIL (Analysis of X-ray spectra by means of Iterative Least Squares). By using simulated spectra in which the intensity of all lines is a priori known, the accuracy and noise-sensitivity of the different background compensation strategies are evaluated: The metho d in which the background is modelled as a linear combination of ortho gonal polynomials is identified as being the most robust and yielding the most accurate results.