Fundamental Parameter Method Using Scattering X-rays in X-ray Fluorescence Analysis

A new fundamental parameter method which employs measured Comptonand Thomson scattered characteristic tube line intensities for the estimation of non-measuring matrix elements has been developed. The concept of substituting a compound matrix by a single element of average atomic number has been efficiently applied to the analysis of biological samples, polymers, liquids, and powders where the non-measuring elements were unknown. It was found that the divergence of the primary x-ray beam and the resulting range of scattering angles should be accounted for in the calculation of scattering intensities. A computational model using Monte Carlo simulations has been developed which considers the distribution of scattering angles for each geometrical location of the sample, and is used in the quantification routine for actual analysis. INTRODUCTION Standardless analysis using fundamental parameter methods is a key method for x-ray fluorescence analysis. However, if unknown non-measurable elements are present in samples such as polymers and biological materials and the elemental composition of the non-measuring elements is not known, accurate analysis was not easily possible. The proposed new method estimates the unknown matrix by measuring Comptonand Thomson scattered characteristic x-ray intensities from the x-ray tube and assumes an element of a corresponding average atomic number to represent an equivalent matrix effect for the analysis in that sample. The idea of average atomic numbers was reported by several authors. However, it was found in our studies that the divergence of the primary x-ray beam and the resulting range of scattering angles should be accounted for in the calculation of scattering intensities. A Monte Carlo simulation model has been developed to consider the distribution of scattering angles for each geometrical location within the detectable region of the sample and is used for the standardless quantification routine.