Non-rigid molecule of copper(II) diiminate Cu[CF<inf>3</inf>C(NH)C(F)C(NH)CF<inf>3</inf>]<inf>2</inf>, its conformational polymorphism in crystal and structure in solutions (Raman, UV-vis and quantum chemistry study)

Calculation of potential energy surface (PES) of isolated molecule of copper(II) diiminate Cu[CF3C(NH)C(F)C(NH)CF3]2 (1) resulted a double-well curve with the minima corresponding to equivalent screwed conformations. The low barrier leads to molecular non-rigidity which seems to be the reason of conformational polymorphism in crystals, reported in [1]. For one of newly found polymorphs, the X-ray structure was determined. The differences in the Raman and UV-vis spectra between differently colored species and their solutions were revealed, they are determined by different geometries of Cu(II) coordination polyhedron and different systems of intermolecular interactions in crystals. Transformations of the polymorphs under thermal, mechanical and photo exposures were studied. © 2015 Elsevier B.V. All rights reserved

Non-rigid molecule of copper(II) diiminate Cu[CF<inf>3</inf>C(NH)C(F)C(NH)CF<inf>3</inf>]<inf>2</inf>, its conformational polymorphism in crystal and structure in solutions (Raman, UV-vis and quantum chemistry study)

Calculation of potential energy surface (PES) of isolated molecule of copper(II) diiminate Cu[CF3C(NH)C(F)C(NH)CF3]2 (1) resulted a double-well curve with the minima corresponding to equivalent screwed conformations. The low barrier leads to molecular non-rigidity which seems to be the reason of conformational polymorphism in crystals, reported in [1]. For one of newly found polymorphs, the X-ray structure was determined. The differences in the Raman and UV-vis spectra between differently colored species and their solutions were revealed, they are determined by different geometries of Cu(II) coordination polyhedron and different systems of intermolecular interactions in crystals. Transformations of the polymorphs under thermal, mechanical and photo exposures were studied. © 2015 Elsevier B.V. All rights reserved

Internal strains and crystal structure of the layers in AlGaN/GaN heterostructures grown on sapphire substrate

In this paper, we investigate the structural properties of AlGaN/GaN heterostructures grown by metal organic chemical vapor deposition on sapphire substrates with different thicknesses using high-resolution x-ray diffraction and Raman scattering methods. We discuss the microscopic nature of spatial-inhomogeneous deformations and dislocation density in the structures. Microdeformations within mosaic blocks and the sizes of regions of coherent diffraction are determined. We reveal a gradient depth distribution of deformations in the mosaic structure of nitride layers, as well as at the interface regions of the sapphire substrate on the microscale level using confocal micro-Raman spectroscopy. We determine that an increase in substrate thickness leads to a reduction in dislocation density in the layers and an increase in the elastic deformations. The features of the block structure of nitrides layers are shown to have a significant influence on their elastic properties