RESUMO
The X-ray back diffraction of (1240) in a monolithic two-plate silicon cavity occurs at photon energy 14.4388 keV, at which 24 beams are simultaneously excited. Based on the dynamical theory of X-ray diffraction, a theoretical approach has been developed for solving the fundamental equation of dynamical theory to investigate this back diffraction and the interference patterns generated by the Fabry-Perot-type resonance that produces intensity undulation in both transmitted and back-reflected beams. The section of dispersion surface and its associated linear absorption coefficients, wavefield intensities and excitation of mode are calculated. The calculated intensity distribution of the transmitted beam is in a good agreement with the observed one. Details about the interaction between the multiply diffracted X-rays and cavity resonant photons are also reported. Procedures of computer programming are also provided.
RESUMO
X-ray back diffraction from monolithic two silicon crystal plates of 25-150 microm thickness and a 40-150 microm gap using synchrotron radiation of energy resolution DeltaE = 0.36 meV at 14.4388 keV clearly show resonance fringes inside the energy gap and the total-reflection range for the (12 4 0) reflection. This cavity resonance results from the coherent interaction between the x-ray wave fields generated by the two plates with a gap smaller than the x-ray coherence length. This finding opens up new opportunities for high-resolution and phase-contrast x-ray studies, and may lead to new developments in x-ray optics.
