Hannes Aiginger

A method for quantitative X-ray fluorescence analysis in the nanogram region

Abstract Application of X-ray total reflexion is used to reduce the background and to improve the ratio between signal and background so that measurements in the nanogram region can be made.

Total reflection X-ray fluorescence analysis with monoenergetic excitation and full spectrum excitation using rotating anode X-ray tubes

A newly constructed measuring chamber for total reflection X-ray fluorescence analysis (TXRF) has been tested for several applications. Full spectrum excitation and monoenergetic excitation of the sample are compared using rotating and standing anode tubes as primary radiation source. Advantages and disadvantages of using a W-C multilayer structure as monochromator in TXRF are discussed. Extrapolated detection limits of 170 fg (1 fg = 10−15 g) for Mn were obtained using a Cu-anode and full spectrum excitation.

Historical development and principles of total reflection X-ray fluorescence analysis (TXRF)

Abstract The historical development of the physical knowledge and the practical application of total reflection X-ray fluorescence analysis (TXRF) is outlined in the introduction. The basic principles of TXRF determining physics and geometry of total-reflection sample support, total-reflection high energy cut-off filters and recent theoretical developments are described together with the principal instrumental developments and the important meetings which stimulated the development and distribution of TXRF.

X-ray fluorescence analysis in the ng region using total reflection of the primary beam

Abstract The article describes the experimental set-up for producing X-ray fluorescent spectra with an essentially reduced background. This is achieved by total reflection of X-rays at a plane, smooth surface of a suitable reflector material. Suprasil (quartz) and germanium are used as reflectors. Liquid samples (1–5 μl) are placed in the centre of the reflector and dried. The experimental facilities enabled the authors to attain detection limits in the ng region with energy dispersive X-ray fluorescence analysis.

Light element analysis with a new spectrometer for total-reflection X-ray fluorescence

Abstract During previous experiments, it has turned out that total-reflection X-ray fluorescence analysis (TXRF) is a well-suited analytical method for the determination of low Z elements (C, N, O, F, Na, Mg, etc.). Because of the advantages in excitation and background reduction, TXRF provides low detection limits. A new spectrometer was designed and constructed with a view to distance reduction, and optimized excitation and detection geometry. A new commercially available Ge (HP) detector offering high efficiency for low-energy fluorescence radiation was used. As the excitation source, a standard Cr-fine-focus tube and a windowless X-ray tube with Cu-anode were tested. Detection limits achieved are in the ng range for carbon and oxygen.

A new spectrometer for total reflection X-ray fluorescence analysis of light elements

Abstract A new spectrometer for total reflection X-ray fluorescence analysis (TXRF) of light elements as C, N, O, F, Na,… has been designed, constructed and realized. This was done under the aspect of optimizing all relevant parameters for excitation and detection under the conditions of Total Reflection in a vacuum chamber. A commercially available Ge(HP) detector with a diamond window offering a high transparency for low energy radiation was used. As excitation sources a special self-made windowless X-ray tube with Cu-target as well as a standard fine-focus Cr-tube were applied. Detection limits achieved are in the ng range for Carbon and Oxygen.

Total reflection X-ray fluorescence analysis with synchrotron radiation monochromatized by multilayer structures

Abstract To achieve lowest detection limits in total reflection X-ray fluorescence analysis (TXRF) synchrotron radiation has been monochromatized by a multilayer structure to obtain a relative broad energy band compared to Bragg single crystals for an efficient excitation. The energy has been set to 14 keV, 17.5 keV, 31 keV and about 55 keV. Detection limits of 20 fg and 150 fg have been achieved for Sr and Cd, respectively.

Total reflection X-ray fluorescence analysis of light elements using synchrotron radiation

Synchrotron radiation from SSRL (Stanford Synchrotron Radiation Laboratory) Beam Line III-4 was used as excitation source for Total Reflection X-ray Fluorescence Analysis (TXRF) of light elements (Z < 14). Due to the outstanding features of synchrotron radiation this source is best suited for the photon induced excitation of light elements offering a large number of photons in the energy range of interest. The high intensity and the natural collimation of the beam is ideal for total reflection geometry. The experiments were performed with a special TXRF spectrometer using an ultrathin window Ge(HP) detector for the energy dispersive measurement of light elements. BL III-4 is equipped with a cut-off mirror (Ecut = 3 keV) for white beam measurements, and a double multilayer monochromator can be inserted. Detection limits of some hundred femtograms have been obtained for Mg with the white beam excitation. Boron could be detected with monochromatic excitation.

A new X-ray tube for efficient excitation of low-Z-elements with total reflection X-ray fluorescence analysis

Abstract Total reflection X-ray fluorescence analysis has turned out to be a suitable method for the analysis of light elements using a Si(Li)-detector with an ultra-thin window. To improve the excitation conditions of the low-Z-elements, a special windowless tube was built. Two different anode configurations are checked, especially the influence of the take-off angle on the spectral distribution of the bremsstrahlung. Influence on detection limits and technical details are presented.

The influence of hydroxyl ions on the thermoluminescence properties of LiF : Mg, Ti

Abstract Hydroxyl ions (OH−)influence the thermoluminescence (TL) properties of LiF : Mg, Ti as is well known. A detailed study of doped single crystals and samples from the melt revealed a correlation between glow curve structure, the existence of certain TL-peaks and the OH−-concentration.