Sandals science

Confined water (blue) in a silica (red and yellow) pore. Water near

Confined water (blue) in a silica (red and yellow) pore. Water near the pore edge has reduced density, caused by the strong orientational surface interaction.
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SANDALS is a neutron diffractometer optimised for amorphous hydrogen containing samples.

Fundamental research has been performed on simple and molecular liquids and glasses, contributing to the understanding of the disordered states of matter. In addition fluids at extreme conditions (supercooled and supercritical) have been investigated.

Recently  the focus of our scientific community has been enlarged by the addition of studies on complex systems, of interdisciplinary and applied interest, such as: 

  • Biomolecules in solution
  • Polymers
  • Ionic liquids
  • Gas absorbed on solid catalysts
  • Nanotechnology
  • Clays

Cover articles:

Structure of Ionic Liquid−Benzene Mixtures

"The drive toward cleaner industrial processes has led to the emergence of ionic liquids as an alternative solvent for reactions. Ionic liquids possess low vapour pressures; therefore, they release effectively no volatile organic solvents. Ionic liquids have been extensively studied for applications in, for example, clean synthesis, electrochemistry, and liquid crystals. (...) Despite the large number of reactions performed in ionic liquids, little is known about the interaction of solutes with the solvent even though these contacts can strongly affect the reaction selectivity and kinetics."

Solvation of Fulleride Anions in Potassium Ammonia Solution

"Since its discovery in 1985, Buckminsterfullerene (C60) has been the subject of intensive scientific and technological activity. Many of the greatest challenges of fullerene science are posed by the low solubility of these molecules in most common solvents. This limits our ability to manipulate fullerenes and their derivatives and restricts their characterization by solution techniques. (...) Nevertheless, an important route to fulleride dissolution involves metal-ammonia solutions. These liquids contain solvated electrons, which allow us to exploit the redox chemistry of fullerene in solution via sequential reduction of C60 fullerite crystals to soluble C60n- anions (n = 1 to 5). In addition to providing a unique arena in which to study fulleride anions, concentrated fulleride-metal-ammonia solutions are showing great promise for purification, charge storage, and thin film deposition." 

Case studies in Chemistry:

Catalysts revealed

Real catalysts are generally nano-crystalline and there are no experimental methods available for structure determination of hydrogenous adsorbed species on such materials. Neutron diffraction has been used to show that it is possible to obtain structural information for adsorbed hydrogenous species on off-the-shelf real catalysts.

Liquid assets

Tetrahydrofuran (THF) is a small ring-shaped molecule consisting of four carbon atoms and an oxygen atom, with two hydrogen atoms attached to each carbon. It is a favourite of chemists who use it as a solvent to carry out both chemical and biochemical reactions important to the pharmaceutical industry. It is particularly relevant in the growing area of nanoscience, whereby liquids with a complex nanostructure are being designed to have highly controlled properties.

Case studies in Biology:

The structure of amino acids in solution

Understanding how the self-organisation of a protein in solution is affected by its aqueous environment is a major challenge which has a long history. Unlike recent studies which have determined atomic-scale structural information in solid state proteins, the application of diffraction techniques to the study of protein hydration and conformation in solution at atomic-scale resolution is limited. 

Case studies in Water and Aqueous Solutions:

Water at the leading edge: interfacial fluids

An investigation of the structure of confined water, using vycor, a silica glass with a random network of ~40 Å pores, as the confining medium.

Isotopes effects on the water structure

In a classical world the structure of D2O should be identical to H2O, but quantum mechanics dictates this cannot be, due to the mass difference between H and D. Those differences are explored using a combination of neutron and x-ray diffraction, and computer simulation.

Geometric structure of Ion hydration shells

Neutron scattering has been employed in conjunction with isotopic substitution of hydrogen for deuterium in the water. This has then been combined with Extended X-ray Absorption Fine Structure (EXAFS) spectral information using computational techniques.

Perturbation of water structure by dissolved ions

Whilst there is plenty of information available about how ions in solution strongly orientate the water molecules that hydrate them, there is surprising paucity of information – and controversy – about how water structure itself (the relative arrangement of one water molecule to another) is affected by the presence of dissolved ions.

 

 

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