Evgenia N. Kolesnik

A comparative study of the anisotropy of lattice strain induced in the crystals of L-serine by cooling down to 100 K or by increasing pressure up to 4.4 GPa

Abstract The anisotropy of lattice strain in the crystals of L-serine (P212121, at ambient conditions a = 5.615(1) Å, b = 8.589(2) Å, c = 9.346(2) Å) on cooling down to 100 K and with increasing hydrostatic pressure up to 4.4 GPa was compared with each other and also with the results previously obtained for the polymorphs of glycine. On cooling, the structure expanded slightly along the crystallographic a-direction, compression along the crystallographic b- and c-directions (normal to the chains of the serine zwitter-ions) was very similar. With increasing pressure, the same structure compressed in all the crystallographic directions, linear strain along c-axis was the largest, linear strain along a-axis — the smallest, linear compression along the b-axis with increasing pressure was slightly larger than that along the a-axis. The different anisotropy of lattice strain of the same structure on cooling and under pressure could be correlated with different response of intermolecular hydrogen bonds to these two scalar actions.

A comparative study of the anisotropy of lattice strain induced in the crystals of DL-serine by cooling down to 100 K, or by increasing pressure up to 8.6 GPa. A comparison with L-serine

Summary The anisotropy of lattice strain in the crystals of DL-serine (P21/n) on cooling down to 100 K and with increasing hydrostatic pressure up to 8.6 GPa was studied by single-crystal X-ray diffraction. In contrast to L-serine undergoing pressure-induced phase transitions at about 5 and 8 GPa, no phase transitions were observed in DL-serine at least up to 8.6 GPa (the highest pressure reached in the experiment). The anisotropy of strain in DL-serine on cooling was shown to be radically different from that with increasing pressure. The response of the crystal structure of DL-serine to cooling and to increasing pressure was considerably different from that of L-serine.

Pressure-induced phase transitions in organic molecular crystals: a combination of X-ray single-crystal and powder diffraction, Raman and IR-spectroscopy

The contribution summarizes the results of recent studies of phase transitions induced by high pressure in a number of molecular organic crystals, such as polymorphs of paracetamol, chlorpropamide, polymorphs of glycine, L- and DL-serine, β-alanine. The main attention is paid to the following topics: (1) Reversible / irreversible transformations; (2) Different behavior of single crystals / powders; (3) The role of pressure-transmitting liquid; (4) The role of the kinetic factors: phase transitions on decompression, or after a long storage at a selected pressure; (5) Isosymmetric phase transitions; (6) The role of the changes in the hydrogen bond networks / intramolecular conformational changes in the phase transitions; (7) Superstructures / nanostructures formed as a result of pressure-induced phase transitions.

Variable temperature (100—295 K) single-crystal X-ray diffraction study of the α-polymorph of glycylglycine and a glycylglycine hydrate

Summary The crystal structures of the α-polymorph of glycylglycine (glygly) and of its hydrate (glygly × 1.5 H2O) were refined by single-crystal X-ray diffraction at 100, 150, 220, and 295 K (glygly) and at 100, 200, 295 K (glygly × 1.5 H2O). The values of the volume thermal expansions of glygly and its hydrate were shown to be larger than for the three polymorphs of glycine. The anisotropy of strain on cooling was analyzed. Despite a smaller bulk thermal expansion measured for glygly, linear strain (both compression and expansion) along the axes of the strain ellipsoids was larger for the structure of glygly, than for the structure of glygly × 1.5 H2O. The contributions of the distortion of the intermolecular hydrogen bonds and of the conformational changes of the zwitter-ions to the lattice strain are considered.

Multilayer Optic Based Components for Synchrotron Sources

The response of crystal structures of L-serine and DL-serine to an increase in hydrostatic pressure was shown to be radically different: reversible phase transitions were observed in L-serine at 5.3 GPa (reverse transition at 4.0 GPa) and 7.8 GPa, whereas the crystal of DL-serine was stable at high pressures up to 8 GPa. Structural distortion and phase transitions were followed by Raman spectroscopy, X-ray single-crystal X-ray diffraction (a laboratory radiation source), high-resolution X-ray diffraction (synchrotron radiation). The structures of the two high-pressure phases were solved and refined from single-crystal and highresolution powder diffraction data; the results were in a good agreement. The anisotropy of strain within the range of stability of the same phases was compared for L - and DL -serine. Pressure-induced changes were radically different from those on cooling. Phase transitions in single crystals of L-serine were shown to proceed in a single-crystal-to-single-crystal mode, via a rapid propagation of an interface after a pronounced induction period. In powder samples, the two phases - a low-pressure and a high pressure phase - co-exist from about 5 up to 10 GPa, and this shows, that the phase transitions in the powder samples are to a large extent kinetically controlled. Acknowledgments: Financial support has been obtained from Alexander von Humboldt Foundation, RFBR (05-03-32468), BRHE Program, and a grant from SB RAS.

X-ray diffraction and Raman spectroscopy studies of high-pressure polymorphs of l- and dl-serine

In the last 20 years, multilayer optics for x-ray and EUV applications have revolutionized the measurement capabilities and the experimental set ups of synchrotron beamlines. Rigaku Innovative Technologies (formerly Osmic) has pioneered these technologies by designing, engineering and manufacturing of distinctive multilayer coatings. We are experienced and internationally recognized for our innovative technologies.We control our production of specified internal roughness on the atomic level while creating layered materials of defined thickness. These multilayers have d-spacings, synonymous for layer-pair thickness, which we can produce uniform, laterally graded, depth graded or even a combination of both gradients. We guarantee our specifications and we have a wide range of metrology technology in house, enabling us to keep our promised specifications and to expand the technical boundaries in our field of applications. Our core capabilities are the detailed knowledge of distinctive multilayer coating technology including the mounting and alignment of optics. We do direct coating on prefigured substrates or, mostly for applications in analytical laboratories, bonding of thin substrates to flat or curved backings. Having delivered thousands of multilayer structures to the analytical scientific market, we are able to design and engineer multilayers on the basis of numerical and analytical simulations of thickness, roughness, required densities and other optical parameters. This technology gives us the possibility to produce just as one example multilayers with a period of 15 Angstroms, a reflectivity of much better than 30% and an energy resolution of better than 0.4%. We also have coatings and multilayer structures for substrates up to 1400 mm length and 400 mm width. The number of chemically different coatings we are able to perform is very broad. This is starting with the classical W/Si through Mo/B4C to a lot of other material combinations. We also design and produce dual wavelength multilayers, narrowand broad-bandwidth multilayers for energy ranges from 40ev to 40 keV. Please see figure (1) for further details. Here we have shown our calculated values for two different multilayer sandwiches. Further material will be shown. Our actual production quality will also be presented.