Energy-dispersive x-ray fluorescence analysis of modern coloured glasses from Marinha Grande (Portugal)

X-Ray Spectrom. 2003; 32: 396–401The elemental composition (K, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Ba, Nd and Pb) of modern coloured glasses was obtained by energy-dispersive x-ray fluorescence (EDXRF) spectrometry. This nondestructive technique is frequently used in the analysis of historical glass objects. Two reference glasses were also measured to assess the overall accuracy of the EDXRF method. Reference and unknown glasses were analysed without any preparation. The coloured glass samples studied belong to the Glass Museum of Marinha Grande and were chosen from two distinct collections, which were characterized by the different concentrations of some elements (K, Ti, Cr, Mn, Fe, Ba and Pb). The determined major elements allowed the identification of two raw materials used in glass manufacture, sand and lime. Multivariate statistical analysis, namely principal component extraction, simplified the identification of some of the colouring chemical elements, associating them with the different colours of the glass objects

Atomic spectrometry update. X-Ray fluorescence spectrometry

This annual review of X-ray fluorescence covers developments over the period 2004 - 2005 in instrumentation and detectors, matrix correction and spectrum analysis procedures, X-ray optics and microfluorescence, synchrotron XRF, TXRF, portable XRF and on-line applications, as assessed from the published literature. The review also covers a survey of applications, including sample preparation, geological, environmental, archaeological, forensic, biological, clinical, thin films, chemical state and speciation studies. As was remarked on in last year's review, substantial numbers of papers continue to be offered in the areas of environmental, industrial and biological/clinical applications, indicating the continued importance of XRF in these fields. Furthermore, several papers have risen to the challenge presented by EU directives in the recycling of waste ( not the least plastic and related materials), landfill issues with the literature in general reflecting the growing contribution that XRF can make to these studies. There has, furthermore, been a continued growth in the application of portable XRF techniques, including, remarkably, both portable synchrotron and portable TXRF instrumentation. Interest continues in the development of silicon wafer based devices, including the silicon drift detectors, CCDs and other nanostructural arrays. These developments demonstrate the current prominence and potential for further growth of XRF in the modern analytical sciences

Self absorption effects in TXRF-XANES measurements a parameter study

Total reflection X-ray Fluorescence (TXRF) analysis in combination with X-ray Absorption Near Edge Structure (XANES) analysis is a powerful method to perform chemical speciation studies at trace element levels. However, when measuring samples with higher concentrations and in particular standards, damping of the oscillations is observed. In this study the influence of self-absorption effects on TXRF–XANES measurements was investigated by comparing measurements with theoretical calculations. As(V) standard solutions were prepared at various concentrations and dried on flat substrates. The measurements showed a correlation between the damping of the oscillations and the As mass deposited. A Monte-Carlo simulation was developed using data of the samples shapes obtained from confocal white light microscopy. The results showed good agreement with the measurements; they confirmed that the key parameters are the density of the investigated atom in the dried residues and the shape of the residue, parameters that combined define the total mass crossed by a certain portion of the incident beam. The study presents a simple approach for an a priori evaluation of the self-absorption in TXRF X-ray absorption studies. The consequences for Extended X-ray Absorption Fine Structure (EXAFS) and XANES measurements under grazing incidence conditions are discussed, leading to the conclusion that the damping of the oscillations seems to make EXAFS of concentrated samples non feasible. For XANES “fingerprint” analysis samples should be prepared with a deposited mass and sample shape leading to an acceptable absorption for the actual investigation

Investigation of polycapillary half lenses for quantitative confocal micro X ray fluorescence analysis

The use of polycapillary optics in confocal micro X ray fluorescence analysis CMXRF enables the destruction free 3D investigation of the elemental composition of samples. The energy dependent transmission properties, concerning intensity and spatial beam propagation of three polycapillary half lenses, which are vital for the quantitative interpretation of such CMXRF measurements, are investigated in a monochromatic confocal laboratory setup at the Atominstitut of TU Wien, and a synchrotron setup on the BAMline beamline at the BESSY II Synchrotron, Helmholtz Zentrum Berlin. The empirically established results, concerning the intensity of the transmitted beam, are compared with theoretical values calculated with the polycap software package and a newly presented analytical model for the transmission function. The resulting form of the newly modelled energy dependent transmission function is shown to be in good agreement with Monte Carlo simulated results for the complete energy regime, as well as the empirically established results for the energy regime between 6 amp; 8197;keV and 20 amp; 8197;keV. An analysis of possible fabrication errors was conducted via pinhole scans showing only minor fabrication errors in two of the investigated polycapillary optics. The energy dependent focal spot size of the primary polycapillary was investigated in the laboratory via the channel wise evaluation of knife edge scans. Experimental results are compared with data given by the manufacturer as well as geometric estimations for the minimal focal spot size. Again, the resulting measurement points show a trend in agreement with geometrically estimated results and manufacturer dat

Total Reflection X-ray Fluorescence attachment module modified for analysis in vacuum

Based on the design of the low cost Total Reflection X-Ray Fluorescence attachment module available since 1986 from Atominstitut (WOBRAUSCHEK-module) which can be attached to existing X-ray equipment, a new version was developed which allows the analysis of samples in vacuum. This design was in particular possible as the Peltier cooled light weight Silicon Drift Detector is following all adjustment procedures for total reflection as angle rotation and linear motion. The detector is mounted through a vacuum feed and O-ring tightening to the small vacuum chamber. The standard 30 mm round quartz, Si-wafer or Plexiglas reflectors are used to carry the samples. The reflectors are placed on the reference plane with the dried sample down looking facing in about 0.5 mm distance the up looking detector window. The reflectors are resting on 3 steel balls defining precisely the reference plane for the adjustment procedure. As the rotation axis of the module is in the plane of the reflector surface, angle dependent experiments can be made to distinguish between film and particulate type contamination of samples. Operating with a Mo anode at 50 kV and 40 mA with a closely attached multilayer monochromator and using a 10 mm2 KETEK silicon drift detector with 8 μm Be window, a sensitivity of 70 cps/ng for Rb was measured and detection limits of 2 pg were obtained