Spectrochimica acta part b-atomic spectroscopy vol:56 issue:11 pages:2283-2292
Calibration of straight total reflection X-ray fluorescence measurements (TXRF) is a matter of discussion for those TXRF users who apply a droplet standard for straight TXRF measurements, at the angle of incidence where particle and film-type contamination show the same fluorescence intensity - the so-called iso-angle as Round Robin tests in the past showed. In order to gain more insight into the differences between several TXRF-equipment types and calibration methods a European Round Robin test was started in 1998 in which 12 companies participated. The Round Robin test comprises 20 different TXRF-tools and one Synchrotron Radiation (SR)-TXRF. Rutherford Back-Scattering measurements (RBS) were performed as absolute reference. Silicon wafers intentionally contaminated by spin-coating and dipping in a spiked NH4OH/H2O2-solution (SC1), respectively, served as test-targets. With exception of one outlier, the results of the comparative analyses can be classified into three groups with similar values. The first group includes the RBS-results, the results of one very old Atomika tool, the results of one Rigaku-tool and those measurements based on special film-type standard wafers or an absolute TXRF calibration method. The second group, including most of the tools from the new Atomika generation, the TREX and the ESRF-beam line, shows an average deviation compared to group 1 by a factor of 1.4, and the third group, containing most of the older Atomika-tools, shows a deviation of 1.8. From these results, it can be concluded that a good calibration of straight TXRF-measurements is mainly determined by the accordance of contamination type on the calibration wafer and the unknown sample. For offsets between these, the application of the bulk sample calibration method or the use of a correction factor is needed. (C) 2001 Elsevier Science B.V. All rights reserved.