Total reflection x-ray fluorescence analysis of light elements under various excitation conditions

AbstractTotal Reflection X-Ray Fluorescence Analysis (TXRF) has been proved to be well suited for the energy dispersive analysis of light elements using a special spectrometer, which is equipped with an energy dispersive detector having all properties for the detection of low energy radiation. The detection of the light elements is strongly influenced by the excitation source which should provide a large number of photons with energies near the K-absorption edge of these elements (0.2 - 3 keV). Various standard tubes with Be-window as well as a homemade windowless tube are compared, all differing in focal size, total power and anode material. Optimized excitation conditions are provided by synchrotron radiation meeting all requirements for excellent excitation of light elements in total reflection geometry such as high brilliance and ideal spectral distribution specially in the low energy region. A comparison of excitation with X-ray tubes as well as with synchrotron radiation is shown. Detection limits of 200 fg for Mg have been obtained with synchrotron radiation.

Download Full-text

Measurements of Soft and Ultrasoft X-Rays with Total Reflection Monochromator

Advances in X-ray Analysis ◽

10.1154/s0376030800021315 ◽

1986 ◽

Vol 30 ◽

pp. 213-223

Author(s):

Tomoya Arai

Keyword(s):

Gas Flow ◽

Bragg Reflection ◽

Optical Resolution ◽

Fluorescence Analysis ◽

Total Reflection ◽

X Rays ◽

Light Elements ◽

Lower Intensity ◽

Measured Intensity ◽

X Ray

The development of X-ray spectrographic analysis of light elements, which are O, C and B, has bee n performed for many applications using an end-window type X-ray tube with Rh-target and thin Be-window, wavelength dispersing devices, which are synthetic multilayers or total reflection mirror (with a specific filter) and a gas flow proportional counter with a thin film window. In Fig. 1 factors related to the intensity measurements in X-ray fluorescence analysis are shown. The excitation efficiency in the soft and ultrasoft X-ray region is very low because of the lower intensity of primary X-rays and low fluorescence yield of light elements. Instead of the wavelength dispersive method of Bragg reflection, having high resolution and low reflectivity, monochromatization combining total reflection by a selected mirror and an appropriate filter offered an alternate approach in order to increase measured intensity with reasonable optical resolution. Synthetic multilayers which have higher resolution and lower intensity compared with the performance of the mirror method have become popular for the detection of soft and ultrasoft X-ray region.

Download Full-text

Txrf-Sources-Samples and Detectors

Advances in X-ray Analysis ◽

10.1154/s0376030800023211 ◽

1995 ◽

Vol 39 ◽

pp. 755-766

Author(s):

P. Wobrauschek ◽

P. Kregsamer ◽

W. Ladisich ◽

R. Riede ◽

Christina Streli ◽

...

Keyword(s):

Synchrotron Radiation ◽

Detection Limits ◽

Fluorescence Analysis ◽

Total Reflection ◽

Light Elements ◽

X Ray

Total reflection x-ray fluorescence analysis (TXRF) has reached a mature state but still improvements are possible in selecting the proper components for TXRF and optimizing them in the best suitable way. Two approaches are presented, the extension of the number of detectable elements after K-shell excitation and the improvement of the detection limits. The results show, that the elements from B to U can be detected by their characteristic K-lines and that detection limits for medium Z elements e.g. Ni in the fg range are achievable. Most of the best results have been measured using synchrotron radiation with spectral modifying devices like multilayer monochromators. Other x-ray sources like a windowless tube with exchangeable anodes of either material Al, Si or Mo were successfully tested for the efficient excitation of light elements.

Download Full-text

Light Element Analysis with TXRF

Advances in X-ray Analysis ◽

10.1154/s0376030800013148 ◽

1991 ◽

Vol 35 (B) ◽

pp. 947-952

Author(s):

Christina Streli ◽

Peter Wobrauschek ◽

Hannes Aiginger

Keyword(s):

Trace Element Analysis ◽

Light Element ◽

Fluorescence Analysis ◽

Analytical Tool ◽

Total Reflection ◽

Light Elements ◽

Element Analysis ◽

X Ray ◽

Background Reduction ◽

Powerful Analytical Tool

AbstractTotal Reflection X-Ray Fluorescence Analysis (TXRF) has become a powerful analytical tool for trace element analysis. Because of its advantages in excitation and background reduction TXRF has been applied for the analysis of light elements (C,O,F,Na,...). A special Ge(HP) detector offering an ultra thin window in combination with a spectrometer specially designed for the requirements of light element analysis was used. Also a new windowless X-ray tube for efficient excitation of the light elements was tested. The system was checked with standard aqueous solutions; detection limits in the ng range (7 ng for O) are obtained.

Download Full-text

Total reflection X-ray fluorescence analysis of light elements with synchrotron radiation and special X-ray tubes

Spectrochimica Acta Part B Atomic Spectroscopy ◽

10.1016/s0584-8547(96)01663-1 ◽

1997 ◽

Vol 52 (7) ◽

pp. 861-872 ◽

Cited By ~ 28

Author(s):

Christina Streli ◽

P Wobrauschek ◽

V Bauer ◽

P Kregsamer ◽

R Görgl ◽

...

Keyword(s):

Synchrotron Radiation ◽

Fluorescence Analysis ◽

Total Reflection ◽

Light Elements ◽

X Ray

Download Full-text

Recent Developments in Txrf of Light Elements

Advances in X-ray Analysis ◽

10.1154/s0376030800023235 ◽

1995 ◽

Vol 39 ◽

pp. 771-779 ◽

Cited By ~ 1

Author(s):

Christina Streli ◽

V. Bauer ◽

P. Wobrauschek

Keyword(s):

Absorption Edge ◽

Detection Efficiency ◽

Fluorescence Analysis ◽

Total Reflection ◽

Low Energy ◽

X Rays ◽

Light Elements ◽

Energy Dispersive Analysis ◽

X Ray ◽

Recent Developments

Total Reflection X-ray Fluorescence Analysis (TXRF) has been proved to be well suited for the energy dispersive analysis of light elements, as B, C, N, O, F, Na, Mg,.,. using a special spectrometer. It is equipped with a Ge(HP) detector offering a sufficient detection efficiency from 180 eV upwards. The obtainable detection limits especially of the light elements are mainly influenced by the excitation source, which should provide a large number of photons with an energy near the K-absorption edge of these elements (from 200 eV upwards). Commercially available X-ray tubes do not offer characteristic X-rays in that range. In former experiments a windowless X-ray tube was built to prevent the low energy X-rays from being attenuated in the Be window. Experiments have been performed using Cu as anode material.

Download Full-text