NEW CORRECTION PROCEDURE FOR X-RAY SPECTROSCOPIC FLUORESCENCE DATA: SIMULATIONS AND EXPERIMENT

摘要

X-ray fluorescence spectroscopy is a widely used method for determining the electronicrnconfiguration and local structure of dilute species with high sensitivity. In the dilute limit, andrnfor thin films, the X-ray fluorescence signal is directly proportional to the atomic sub-shellrnabsorption coefficient. However, for concentrated samples, the well-documented self-absorptionrneffect often leads to the severe suppression of XANES (X-ray Absorption Near-Edge Structure)rnand EXAFS (Extended X-ray Absorption Fine-Structure) amplitudes. Thus to recover the realrnvalue of the sub-shell absorption coefficient, it is important to apply correction procedures to thernmeasured fluorescence spectra. In this paper, we describe a new straightforward method torncorrect for self-absorption effects (the difference in the measured fluorescence signal comparedrnto that of the true sub-shell photoabsorption coefficient) in XANES and EXAFS fluorescencernmeasurements. Using a variety of sample and detector configurations, this method is used tornextract the sub-shell absorption coefficient on elemental nickel and thick single-crystals ofrnGd_3Ga_5O_(12) and LaAlO_3.