Total Reflection X-Ray Fluorescence Analysis Excited by Synchrotron Radiation (SR-TXRF): Variation of Excitation Conditions and Sample Geometries

Abstract

The use of synchrotron radiation as the excitation source for total reflection x-ray fluorescence analysis (SR-TXRF) in combination with a multilayer structure for monochromatization led to detection limits in the femtogram range for medium-Z elements. Experiments were performed at the Hasylab Beamline L using bending magnet radiation. Different methods for the modification of the spectral distribution, viz. multilayer monochromatization, insertion of a high-energy cut-off and a simple filter technique, were compared. Also, several possible types of geometrical arrangement of the sample and detector were examined to establish whether an improvement in excitation or detection conditions is possible. Samples were of evaporated droplets of aqueous or acidic solutions of several elements at various concentrations. Spectra were evaluated and the data used to extrapolate the detection limits (DL). Monochromatization of the synchrotron radiation in combination with a sample carrier positioned in the vertical plane and a side-looking detector in the plane of polarization turned out to give the best results with a DL of 15 fg for Ni.