X-RAY STANDING-WAVE EFFECTS IN GRAZING-INCIDENCE X-RAY DIFFRACTION FROM POLYCRYSTALLINE MULTILAYERS

J. Krčmář¹ and V. Holý²

¹Institute of Condensed Matter Physics, Masaryk University Brno, Czech Republic,

²Department of Electronic Structures, Charles University Prague, Czech Republic

Grazing-incidence geometry is frequently used in powder x-ray diffraction from thin polycrystalline layers, since it allows suppressing the diffraction from substrates. If this geometry is used for a polycrystalline periodic multilayer, the diffracted intensity is modulated by a standing wave created by the interference of the radiation transmitted through the multilayer stack with the wavefields specularly reflected from the superlattice interfaces. Similarly, the radiation being diffracted from the polycrystalline structures is reflected specularly from the interfaces and a standing-wave interference pattern results as well.

The standing-wave effects in diffraction from polycrystals have been analyzed theoretically in our previous work [1], this presentation demonstrates a series of experimental measurements obtained from Ni/C periodic multilayers. The measurements have been carried out at ESRF using x-ray energies far away and close to the NiK absorption edge, so that anomalous scattering effects were present. The experimental data have been modeled using a theoretical approach based on the distorted-wave Born approximation and a good fit to the theory was achieved.

The experimental data obtained demonstrate that the method can be used for the investigation of the polycrystalline multilayers, especially for studying the profiles of the grain sizes and strains across the multilayer stack.

The work has been supported by the Ministry of Education of the Czech Republic (Research project MSM0021622410).

[1] P. F. Fewster, N. L. Andrew, V. Holý, and K. Barmak, Phys, Rev. B 72 (2005), 174105.