Benefits of Improved Resolution for Edxrf

The accuracy and precision of energy dispersive X-ray fluorescence (EDXRF) improve with improved detector energy resolution. However, there are trade-offs between the highest energy resolution and the highest count rates, and there are practical difficulties in achieving the very best energy resolution. Energy resolution differentiates systems but the benefits of improved energy resolution, in accuracy and precision of the analytical results, are not always clear. In the results reported here, EDXRF analysis was carried out on a set of reference materials as a function of energy resolution. Several different detectors were used (Si-PIN diodes, silicon drift diodes (SDD), and CdTe detectors) with a range of operating parameters. At 5.9 keV, the resolution ranged from 139 eV to 325 eV for SDD and Si-PIN devices, and 450 eV for CdTe. The results show that benefits of improved resolution depend on the detector, sample, and analysis goals. For isolated peaks with little background, e.g., Pb in paint, the precision was independent of energy resolution. For spectra with widely spaced peaks, e.g., the Fe, Cr, and Ni peaks in a steel alloy, the best results were found at moderate energy resolution with high count rates. For complex spectra with overlapping peaks, e.g., Au in jewelry, the best energy resolution yielded the best results. In general, energy resolution should good be enough to separate the peaks of interest. Further improvements in precision and accuracy are obtained by improved counting statistics, i.e., operating at high count rates or using a larger area detector.