Abstract
A new technique of re#ectance X-ray absorption ne structure (REFL-XAFS) utilizing waveguides where X-rays are re#ected many times along the waveguide surface is discussed. The multiple total re#ection (MTR) phenomenon highly increases X-ray interaction with the waveguide surface and hence o!ers higher sensitivity compared to conventional (single re#ection) REFL-XAFS. On the one hand, this technique is a direct structural method for characterizing waveguides (e.g. capillaries) where the application of other methods is very di$cult. On the other hand, the conventional thin wafer can be transformed to a whispering-gallery (WG) waveguide by bending to a curved mirror. Ray tracing calculations demonstrate that the WG waveguide is very suitable for REFL-XAFS measurements. This method was experimentally realized for a cylindrically bent silica wafer with the surface covered with a GeO 2 monolayer. The Ge K-edge REFL-XAFS measurements were performed using both MTR and conventional techniques. The MTR technique allows us to achieve about 20-fold gain in the signal-to-background ratio compared with the conventional technique. The MTR phenomenon discussed in this paper can provide new possibilities to study clean surfaces, ultrathin lms and adsorbed molecules. ( 2000 Published by Elsevier Science B.V. All rights reserved.
Published Version
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