Integrated GD-OES/XRF element analyzer (GD-OES = glow discharge optical emission spectroscopy, XRF = X-ray fluorescene)

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Quantitative element analysis plays a central role in many fields of physics, material science and engineering. In the following, typical application examples of the applying working groups at the University of Duisburg-Essen are given:When researching novel materials for renewable energies, it is essential to know thicknesses and composition of the fabricated thin films, in particular of the absorber layers. In order to arrive at precise statements about the device quality, it is equally important to obtain information about the depth-dependent element distribution, in particular for multinary materials like chalkoyprites (researched by AG Schmid) or perovskites (AG Kirchartz, AG Lupascu, AG Winterer). Also for magnetic heterostructures made from multiferroic materials the composition is decisive. Multiphase nanocomposite layers like CoFe2O4/BaTiO3 are currently under research by the involved groups AG Wende and AG Lupascu. Nanoparticles of multiferroic nature (AG Wende, AG Lupascu) or based on nitrides and oxides for the application in photocatalysis (AG Winterer) are a subject of research, which basis on the knowledge of their composition. Finally, for oxides (Al2O3, ZrO2) doped with rare earth elements or transition metals (Cr, Eu, Tb) the concentration and distribution of doping ions within the lattice are determining for example the thermographic properties and are analyzed by the AG Atakan.The broadness of the mentioned examples illustrates the necessity of covering a broad spectrum of elements. At the same time, a resolution down to the ppm range shall be reached. For this, on the one hand side the integral composition values of solid, powder and where necessary liquid samples are of interest. On the other hand, for solid samples, in particular thin films, the depth-dependent element distribution is relevant.As measurement methods, which allow a quick analysis over a depth of up to several micrometers with a measurements precision in the range of few ppm, two methods offer themselves: X-ray fluorescence (XRF) for integral values also of powder and liquid samples and glow-discharge optical emission spectroscopy (GD-OES) for depth-resolved results of solid samples. Measurements using energy-dispersive XRF are non-destructive and available starting from the element Na. GD-OES in contrast measures in an abrasive way, but provides access to the light elements like C, O and N. The combination of the two methods XRF and GD-OES allows an optimal coverage of a broad element spectrum under minimal compromises of precision and non-destructiveness. The integrated version additionally facilitates a cross calibration to obtain reliable quantitative values. A thorough calibration is the basis for meaningful measurements, which are expected from the proposed integrated GD-OES/XRF element analyzer.