Total Reflection X-Ray Fluorescence
Published Online: 15 SEP 2006
Copyright © 2000 John Wiley & Sons, Ltd. All rights reserved.
Encyclopedia of Analytical Chemistry
How to Cite
Wobrauschek, P. and Streli, C. 2006. Total Reflection X-Ray Fluorescence. Encyclopedia of Analytical Chemistry.
- Published Online: 15 SEP 2006
Total reflection X-ray fluorescence (TXRF) analysis is an energy-dispersive (ED) X-ray fluorescence (XRF) technique using a special excitation geometry. The narrow collimated beam impinges at grazing incidence on a special sample carrier. This is a flat polished quartz plate on which the sample is deposited. The most significant advantages of TXRF over conventional XRF analysis are the improved detection limits achieved by inherent signal increase and reduced background. Detection limits are in the picogram range for X-ray tube excitation and even down to femtograms for excitation using synchrotron radiation (SR). The main application is the analysis of some microliters of a liquid sample deposited and dried on the quartz reflector or of some microliters of slurry or microgram grains of solid samples. The most widely used application is the quality control of contaminations on Si wafer surfaces. The detection limits demanded by the semiconductor industry can be reached today using X-ray tube excitation, but metrology shows that in the future SR is required or special preconcentration techniques. Straight TXRF is the only analytical technique offering nondestructive and spatial resolved analysis. A special ED detector with an ultrathin window is suitable for the detection of low atomic number, Z elements (C upwards) using TXRF. Another promising application is the characterization of thin layers on a reflecting surface or implanted atoms in Si by variation of the incidence angle and measurement of the fluorescence signal. It is possible to determine the elements forming the layer, the layer thickness and its density. For thin layered samples as well as implantations, thickness, depth and depth profile for implanted atoms can be evaluated by comparing experimental results with theoretical models.