TY - JOUR A1 - Scholze, F. A1 - Procop, Mathias T1 - Detection efficiency of energy-dispersive detectors with low-energy windows N2 - Energy dispersive X-ray spectrometry offers the opportunity for fast composition determination of specimens by X-ray fluorescence or electron probe microanalysis. For fundamental parameter based quantification, the knowledge of the detection efficiency of the spectrometer is essential. At low energies the efficiency is strongly influenced by X-ray absorption in the radiation entrance window. State-of-the-art windows consist of polymer foil containing C, N, and O, coated with Al and in some cases with a special B compound. The foil is supported by a Si grid to withstand the atmosphere pressure. The absorption of all these components must be known to describe the detection efficiency. The transmittance of three types of widely used commercial windows has been measured. Transmittance curves have been fitted by analytical expressions using tabulated mass absorption coefficients. Because tabulated mass absorption coefficients do not consider near edge effects, there are strong deviations between measured and calculated transmittance below 0.6 keV. It is proposed to model the spectrometer efficiency by the measured window transmittance and calculated absorptions from front contact and possible contaminations. This reduces the number of unknown parameters drastically. PY - 2005 U6 - https://doi.org/10.1002/xrs.859 SN - 0049-8246 VL - 34 IS - 6 SP - 473 EP - 476 PB - Wiley CY - Chichester AN - OPUS4-11936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bjeoumikhov, A. A1 - Arkadiev, V. A1 - Eggert, F. A1 - Hodoroaba, Vasile-Dan A1 - Langhoff, N. A1 - Procop, Mathias A1 - Rabe, J. A1 - Wedell, R. T1 - A new microfocus x-ray source, iMOXS, for highly sensitive XRF analysis in scanning electron microscopes N2 - Scanning electron microscopes are usually equipped with energy-dispersive X-ray detectors for electron probe microanalysis. This widespread analytical method allows investigators to determine the elemental composition of specimens with a spatial resolution of about 1 µm. However, owing to the electron-specimen interaction, the emitted spectra reveal, in addition to characteristic lines, also a high level of continuous bremsstrahlung background. As a result, elements with low concentrations cannot be identified. The minimum detection limit can be diminished by two orders of magnitude if the characteristic lines are excited as fluorescence by an additional x-ray source. In this case, the emergence of bremsstrahlung is considerably reduced. Combining a high-brilliance microfocus x-ray tube with efficient polycapillary optics enables one to realize an experimental arrangement for performing local fluorescence analysis at the same point where the electron beam hits the sample. The polycapillary optics under consideration focuses the emitted x-radiation onto focal spots between 30 and 100 µm in diameter. Count rates of several thousands cps have been achieved. Elemental maps have been obtained by means of the motorized specimen stage of the microscope. Copyright © 2005 John Wiley & Sons, Ltd. KW - Micro-XRF KW - Microfocus x-ray source KW - EPMA KW - SEM PY - 2005 U6 - https://doi.org/10.1002/xrs.872 SN - 0049-8246 VL - 34 IS - 6 SP - 493 EP - 497 PB - Wiley CY - Chichester AN - OPUS4-11228 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Procop, Mathias A1 - Alvisi, M. A1 - Blome, M. A1 - Griepentrog, Michael A1 - Hodoroaba, Vasile-Dan A1 - Karduck, P. A1 - Mostert, M. A1 - Nacucchi, M. A1 - Rohde, M. A1 - Scholze, F. A1 - Statham, P. A1 - Terborg, R. A1 - Thiot, J.-F. T1 - The determination of the efficiency of energy dispersive X-ray spectrometers by a new reference material T2 - 9th Europ. Workshop of Europ. Microbeam Anal. Soc. and 3rd Meeting of International Union of Microbeam Analysis Societies CY - Florence, Italy DA - 2005-05-22 PY - 2005 AN - OPUS4-7133 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -