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Comparison of different excitation modes for the analysis of light elements with a TXRF vacuum chamber

Published online by Cambridge University Press:  22 May 2015

J. Prost ,
P. Wobrauschek  and
C. Streli
J. Prost*
Affiliation:
Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Vienna, Austria
P. Wobrauschek
Affiliation:
Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Vienna, Austria
C. Streli
Affiliation:
Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Vienna, Austria
*
a)Author to whom correspondence should be addressed. Electronic mail: josef.prost@ati.ac.at
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Abstract

The aim of this work was to compare different excitation modes for the analysis of light elements from carbon (Z = 6) upwards using a total reflection X-ray fluorescence analysis (TXRF) vacuum chamber which allows the attachment of different X-ray tubes and detectors. In the first set of experiments, two water-cooled high-power X-ray tubes with Cr (Z = 25) and Cu (Z = 29) anodes, respectively, were compared with an air-cooled low-power tube with Mo anode (Z = 42) and a thin Be window for the transmission of Mo-L lines. In the first two cases, monochromatic Kα radiation was used for excitation, while in the case of the Mo tube the multilayer acted as a cut-off reflector and part of the Mo bremsstrahlung continuum together with the Mo-L series were used for excitation. Multi-element standards containing elements ranging from Na (Z = 11) to Ti (Z = 22) were analyzed by a silicon drift detector (SDD) with a 300 nm ultrathin polymer window (UTW). Detection limits were calculated and compared for the three excitation modes. The second set of experiments was performed using an air-cooled low-power X-ray tube with Rh anode (Z = 45) in order to show that a conventional SDD with a 25 μm beryllium window can be used for the detection of elements from Na upwards. The use of compact air-cooled low-power X-ray tubes together with Peltier-cooled SDDs with UTW should lead to the development of highly sensitive tabletop vacuum TXRF spectrometers with a design optimized for the analysis of light elements. Detection limits as achieved by vacuum chambers using conventional water-cooled high-power tubes (e.g. Streli et al., 2004) are realistically achievable with the new approach.

Keywords

Total Reflection X-ray Fluorescence Analysis (TXRF)low Z elementslow-power X-ray sourcesexcitation modes
Type
Technical Articles
Information
Powder Diffraction , Volume 30 , Issue 2 , June 2015 , pp. 93 - 98
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Copyright
Copyright © International Centre for Diffraction Data 2015 

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