Search results for "Diffraction"

The Low Barrier Hydrogen Bond in the Photoactive Yellow Protein: A Vacuum Artifact Absent in the Crystal and Solution

2016

Journal of the American Chemical Society 138(51), 16620 - 16631 (2016). doi:10.1021/jacs.6b05609

Influence of chirality on the structure of phospholipid monolayers.

1993

Controlling the molecular diffusion in MOFs with the acidity of monocarboxylate modulators.

2021

The catalytic performance of metal-organic frameworks (MOFs) is related to their physicochemical properties, such as particle size, defect-chemistry and porosity, which synthetic control can be potentially achieved by coordination modulation. By combining PXRD, 1HNMR, FT-IR, N2 uptake measurements we have found insights that the different types of defects (missing linker or missing clusters consequence of the spatial distribution of missing linkers, and the combination of both) could be controlled by the type of modulator employed. We show that the molar percent of defects, either as missing linkers or as part of missing cluster defects, is related to the modulator’s acidity and subse…

A Bis(diazadiene) Adduct of MoCl 2 : Mononuclear, Octahedral, Undistorted and Diamagnetic

2004

The complex [MoCl2(iPr2dad)2] (iPr2dad = iPrN=CH−CH=N−iPr) is obtained in one step by reduction of [MoCl3(THF)3] in the presence of iPr2dad. The X-ray structure reveals a relatively undistorted octahedral coordination geometry with a relative cis configuration and points to a more appropriate description of the ligands as enediamides. The NMR investigation is in agreement with the same cis structure in solution and underlines the diamagnetism of the compound, at odds with previously reported very similar complexes. A bulk magnetic susceptibility measurement further confirms the compound’s diamagnetism. No equilibrium with a dinuclear, metal-metal bonded species is apparent from the solution…

X-ray diffraction measurements of Mo melting to 119 GPa and the high pressure phase diagram

2009

In this paper, we report angle-dispersive X-ray diffraction data of molybdenum melting, measured in a double-sided laser-heated diamond-anvil cell up to a pressure of 119 GPa and temperatures up to 3400 K. The new melting temperatures are in excellent agreement with earlier measurements up to 90 GPa that relied on optical observations of melting and in strong contrast to most theoretical estimates. The X-ray measurements show that the solid melts from the bcc structure throughout the reported pressure range and provide no evidence for a high temperature transition from bcc to a close-packed structure, or to any other crystalline structure. This observation contradicts earlier interpretation…

The influence of the raw material and production method on the morphology, microstructure, chemical and phase composition of tetrabasic lead sulfate …

1992

Abstract Tetrabasic lead sulfate (4BS) produced by two different methods (solution and paste) and from two different raw materials (tetragonal PbO and leady oxide) were charaterized by different analytical techniques. The techniques applied were wet-chemical methods, scanning electron microscopy, transmission electron microscopy and X-ray powder diffraction. The preparation method was observed to be the most decisive factor influencing the structure and the morphology of the 4BS pastes in this study.

Synthesis and characterization of indium oxide at high pressures

2018

Introducción: La naturaleza es sorprendente pero a la vez limitada. A mi entender, nada tiene más potencial que aplicar el ingenio humano para modificar lo que nos rodea y crear algo completamente nuevo. La Física de la Materia Condensada es un campo que actualmente está ganando importancia en la Física moderna. En virtud de los éxitos logrados en Física de la Materia Condensada se han producido enormes avances en el campo de la electrónica cuántica, de los semiconductores y de la ciencia de materiales, teniendo como resultado numerosas aplicaciones tecnológicas que han cambiado nuestras vidas drásticamente en los últimos 50 años. Una de las ramas de la Física de la Materia Condensada es el…

Unraveling the packing pattern leading to gelation using SS NMR and X-ray diffraction: direct observation of the evolution of self-assembled fibers

2010

A detailed understanding of the mode of packing patterns that leads to the gelation of low molecular mass gelators derived from bile acid esters was carried out using solid state NMR along with complementary techniques such as powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and polarizing optical microscopy (POM). Solid state 13C{1H} cross polarization (CP) magic angle spinning (MAS) NMR of the low molecular mass gel in its native state was recorded for the first time. A close resemblance in the packing patterns of the gel, xerogel and bulk solid states was revealed upon comparing their 13C{1H}CPMAS NMR spectral pattern. A doublet r…

One-step growth of isolated CdO nanoparticles on r-sapphire substrates by using the spray pyrolysis methodology

2014

In spite of the remarkable properties of CdO, there are only a few reports on CdO nanostructures, especially on isolated NPs. In this paper, we analyze the growth of isolated CdO nanoparticles (NPs) on 0.5° miscut r-sapphire substrates by using the spray pyrolysis methodology in its classical configuration. A systematic study has been performed to optimize the growth parameters such as precursor concentration, growth time, spray rate and growth temperature to obtain CdO NPs (size: 6–10 nm to 35–100 nm depending on the growth conditions). The study shows the control over the size and density of the CdO nanoparticles that can be achieved by adjusting the growth parameters. The CdO nanoparticl…

Electrochemical deposition of Ag2Se nanostructures

2017

Abstract AgSe based nanostructures (nanowires or nanotubes) were obtained by electrodeposition. A systematic investigation was carried out, varying concentration of the precursors, pH of the electrolytic solution, ligands, and deposition mode, to study the effect of all these parameters on the growth of nanostructures. Nanostructure morphology depends also on the type of metal that was used as support, due to the secondary reaction of hydrogen evolution. On Ni support, the H2 evolution reaction led to formation of only nanotubes, while on copper substrate also nanowires were obtained. Composition of nanostructures depends strongly on solution pH. X-ray diffraction and Raman spectroscopy sho…