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S. L. Morelhao

Publications and source records attributed to S. L. Morelhao.

2 recordsLinked to original sources

Simulation of bright and dark diffuse multiple scattering lines in high-flux synchrotron X-ray experiments

We present a theoretical framework for understanding diffuse multiple scattering (DMS) in single crystals, focusing on diffuse scattering-Bragg (DS-Bragg) channels. These channels, when probed with high-flux, low-divergent monochromatic synchrotron X-rays, provide well-defined visualizations of Kossel lines. Our main contribution lies in modeling the intensity distribution along these lines by considering DS around individual reciprocal lattice nodes. The model incorporates contributions from both general DS and mosaicity, elucidating their connection to second-order scattering events. This comprehensive approach advances our understanding of DMS phenomena, enabling their use as probes for complex material behavior, particularly under extreme conditions.

physics.optics

On the high accuracy lattice-parameters determination by n-beam diffraction: Theory and application to the InAs quantum dots grown over GaAs(001) substrate system

Ultra-precise lattice parameter measurements in single crystals are achievable, in principle, by X-ray multiple diffraction (XMD) experiments. Tiny sample misalignments have hindered the systematic usage of XMD in studies where accuracy is an important issue. In this work, theoretical basement and methods for correcting general misalignment errors are presented. As a practical demonstration, the induced strain of buried InAs quantum dots grown on GaAs (001) substrates is determined. Such a demonstration confirms the possibility to investigate epitaxial nanostructures via the strain field that they generate in the substrate crystalline lattice. This work was supported by the Brazilian founding agencies FAPESP (grant numbers 02/10185-3 and 02/10387-5), CNPq (proc. number 301617/95-3 and 150144/03-2) and LNLS (under proposal number D12A-XRD1 2490/03).

cond-mat.mtrl-sci