Contribution of the IBA group to the EU5 MICRO-XRF project

Complete text of publication follows. The overall objective of the EU5 project was the development of synchrotron radiation induced micro X-ray fluorescence analysis (MICRO-XRF) as an accurate and traceable elemental analysis on the microscopic level. The Ion Beam Analytical group of ATOMKI took part in this project for two years and contributed to four work packages from the seven. The most important results are summarised below. WP3: Heterogeneity characterisation of existing Certified Reference Materials (CRMs). This part of the project dealt with experimental testing of four candidate Reference Materials with the objective to determine their micro-homogeneity and minimum representative sample mass (MRSM) for the use in the corresponding certification reports of these CRMs. Measurements were carried out on four pelletized samples (BCR-176R incineration ash; BCR-277R estuarine sediment; BCR-280R lake sediment; BCR-320R canal sediment) at the scanning nuclear microprobe laboratory of ATOMKI. Besides determining MRSM-s, our measurements enlightened the conceptual differences of the existing definitions for the minimum representative sample mass and urged the development of new models. WP4: Feasibility study of reference materials. The goal of this work package was to select, produce and characterize standards in order to determine the sensitivity and the lateral resolution of the micro-XRF technique. Within the framework of this work package, depth profile and implanted dose of fluorine in implanted silicon samples were measured using the Proton Induced Gamma-ray Emission (PIGE) method. Our results show that PIGE can compete with Secondary Ion Mass Spectrometry (SIMS) in fluorine depth profiling. Furthermore, it is a non-destructive technique. WP5: Intercomparison study of selected materials. In WP5 the acceptability of MICRO-XRF as a potential primary tool for microscopic trace elemental analysis was investigated. The ATOMKI IBA group applied Particle Induced X-ray Emission (PIXE) and Rutherford Back-scattering Spectrometry (RBS) techniques as independent methods in this interlaboratory study. Activities focused on determining the concentrations of ZnO deposited in the form of thin (1-10 nm) films on various substrates. WP6: Development of micro-PIXE as a quantitative method. The ATOMKI-IBA Group and the University of Surrey took part in this work package, where an intercomparison study of quantitative PIXE analysis with high lateral resolution was implemented. Our aim was to investigate the traceability, accuracy and reproducibility of protocols and reference materials for quantitative elemental microanalysis using probe beam techniques with a micrometer spatial resolution. The results of the intercomparison measurement with BCR glass demonstrated that, at least under controlled conditions, the reproducibility and accuracy of standardless PIXE analysis could be within 5%. We can conclude that this technique is a valuable tool for micro-XRF calibration. (author)