In x-ray-excited surface spectroscopies one of the most relevant figures of merit is the overlayer versus substrate signal ratio. In this work we propose to utilize the Borrmann (or anomalous-transmission) effect, which takes place in perfect crystals, in order to have a weaker interaction of the incident beam with the substrate. In this way the overlayer versus substrate signal ratio can be enhanced, roughly by a factor varying between 3 and 20, depending on the kind of spectroscopy utilized. To demonstrate the feasibility of this method, the fluorescence signal intensity of a Ge overlayer (200 angstrom thick) is compared with the Si substrate scattering both in transmission and in reflection geometry. The synchrotron radiation from a wiggler insertion device was used as an x-ray source. An improvement of a factor about 3 is observed in the present experiment, in agreement with the expected value for this particular case. The monochromatization properties of such an arrangement are also presented.
Lagomarsino, S., Stefani, G., Castrucci, P., Letardi, P., Scarinci, F., Savelli, G., et al. (1992). APPLICATION OF THE BORRMANN EFFECT TO X-RAY MONOCHROMATIZATION AND TO THE OVERLAYER VERSUS SUBSTRATE SIGNAL-RATIO ENHANCEMENT RID G-7348-2011. PHYSICAL REVIEW. B, CONDENSED MATTER, 45(12), 6953-6956 [10.1103/PhysRevB.45.6953].
APPLICATION OF THE BORRMANN EFFECT TO X-RAY MONOCHROMATIZATION AND TO THE OVERLAYER VERSUS SUBSTRATE SIGNAL-RATIO ENHANCEMENT RID G-7348-2011
STEFANI, Giovanni;
1992-01-01
Abstract
In x-ray-excited surface spectroscopies one of the most relevant figures of merit is the overlayer versus substrate signal ratio. In this work we propose to utilize the Borrmann (or anomalous-transmission) effect, which takes place in perfect crystals, in order to have a weaker interaction of the incident beam with the substrate. In this way the overlayer versus substrate signal ratio can be enhanced, roughly by a factor varying between 3 and 20, depending on the kind of spectroscopy utilized. To demonstrate the feasibility of this method, the fluorescence signal intensity of a Ge overlayer (200 angstrom thick) is compared with the Si substrate scattering both in transmission and in reflection geometry. The synchrotron radiation from a wiggler insertion device was used as an x-ray source. An improvement of a factor about 3 is observed in the present experiment, in agreement with the expected value for this particular case. The monochromatization properties of such an arrangement are also presented.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
