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TXRF vacuum chamber with sample changer (WOBISTRAX) for low Z and high Z determination (Government of India)

A special TXRF spectrometer is designed and manufactured by the x-ray group of TU WIEN Atominstitut (Streli/Wobrauschek). Core function is the analysis by TXRF of LOW Z and HIGH Z elements using 2 air cooled low power x-ray tunes one with Cr anode and the second with Rh anode. Cr - Ka x-rays are used to excite from C to Ti via K shell excitation and Rh.

K x-rays are used for excitation of the elements K to Mo by the K series and the other elements up to U via the L-line series. A special detector is required to collect the low energy emission lines from C upwards which is equipped with an ultra thin window of 300m polymer and a magnetic electron trap. Higher energy photo or Compton electrons are shielded by a thin window of Be or Kapton. All features described can be realized only if the measurements are performed in vacuum. This feature holds 3 inherent advantages: all absorption problems in air are not existing, the scattering of the x-rays in air is not existing and as there is no Ar the x-ray fluorescence of this element is nor in the spectrum. Another core feature is the easy way of operation by loading up to 12 sample carriers and use the automatic sample changer feature.

The analytical capacity is given by performing all measurements in total reflection geometry leading to lowest background in the spectrum and yields a double as high fluorescence intensities compared to conventional excitation modes. Quantification is achieved applying the thin film approximation giving a linear correlation of measured intensities and concentrations of the sample elements - an internal standard added to the sample allows after calibration of the spectrometer the simple calculation of the unknown concentrations present in the specimen.