Page 15 - ILLS Annual Report 2018

SCIENTIFIC HIGHLIGHTS
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Electric field effects on the spin structure of multiferroics are addressed using a newly available electric-field set-up for SANS. Two Highlight articles demonstrate the continued interest in superconductivity and magnetic nanoparticles. Polarised neutron reflectometry explores the structural and magnetic integrity of thin layers, while science cases range from proximity effects of superconductivity on ferromagnetism to magnetic nanoparticles assemblies under alternating fields.
COLLEGE 6 – STRUCTURE AND DYNAMICS OF DISORDERED SYSTEMS
M.M. Koza (College 6 Secretary)
Over the past few years, experiments on water and ionic liquids have become the two supporting columns of College 6’s activities. The broadening of the College’s sphere of action to confined
and porous systems consolidated this trend in 2018. With this consolidation, the complexity of materials has increased and
the experimental protocols have become more refined. Pressure experiments, polarisation analysis and multiple instruments are requested for the majority of projects, for complementary studies
of structure and dynamics and extensive coverage of structure
and dynamic ranges. Two Highlights reflect the wide spread of College 6 interests. In the first, inelastic polarisation analysis is exploited to quantitatively determine the magnitude of quantum effects in the dynamics of H2O and D2O — essential information for confronting inconsistent data in the literature and improving widely employed water potentials. In the second, layered structures of halogen-free ionic liquids and propylene carbonate are examined for their practicality as actively friction-controlled lubricants, highlighting the potential of ionic liquids beyond their application in batteries, solar cells, super-capacitors and electrochemical devices.
COLLEGE 7 – SPECTROSCOPY IN SOLID STATE
PHYSICS AND CHEMISTRY
T. Weber (College 7 Secretary)
College 7 deals with non-magnetic spectroscopy in solid-state systems, encompassing a broad range of topics that include the determination of phonon dispersion relations and densities of states, phonon softening effects due to anharmonic interactions, and structural and orbital-ordering phase transitions. Additional topics include ionic relaxation and diffusion, as well as the dynamics of molecular and physio-/chemisorbed systems.
While College 7 has a wide variety of cold- and thermal-
neutron spectrometers and diffractometers at its disposal, in the recent proposal round most days of beamtime were awarded
to experiments on the high-flux, thermal-neutron, three-axis spectrometer IN8, the IN1-LAGRANGE spectrometer, the high-resolution spin-echo instrument IN11 and the time-of-flight spectrometers IN6-SHARP and IN5. The complexity of both the investigated systems and the instrumental resolution functions typically require sophisticated theoretical models and data analysis
tools. Assistance in these fields is provided by the ILL’s Theory and Software groups.
COLLEGE 8 – STRUCTURE AND DYNAMICS OF
BIOLOGICAL SYSTEMS
N. Coquelle (College 8 Secretary)
College 8 focuses on biological samples, using a large palette of techniques and instruments to unravel molecular structure and link it to their function and/or dynamics. Neutron crystallography (D19, LADI and soon DALI) provides a unique technique for visualising hydrogen/ deuterium atoms of proteins and finely understanding their catalytic mechanism or binding of small molecules. Studies in solutions are performed using the SANS machines (D11, D22 and D33); taking advantage of the deuteration, signals from a molecular type (DNA vs protein, for example) can be masked out. Reflectometers (Figaro, D17) as well as the diffractometer D16 are excellent instruments for studying the properties of bio-mimicking surfaces (model lipidic bilayers) and how some macromolecules can interact with and/or modify these surfaces. Finally, the set of neutron spectrometers (IN15, IN13, IN11) is used to gain insight into the dynamics of these biological system over a large range of time and q.
Multiple laboratories are available on the EPN campus to help with sample preparation, e.g. the D-lab for the perdeuteration of biological molecules as well as the EMBL biology laboratories for specific sample preparation. Also, the PSB platform and the PSCM offer a large variety of complementary techniques to further characterise samples.
COLLEGE 9 – SOFT CONDENSED MATTER
I. Hoffmann (College 9 Secretary) and Ph. Gutfreund (focus
group Secretary)
More than 200 proposals in the last two proposal rounds underline both the high level of overall activity in the field of soft condensed matter and the great demand for neutrons. In 2018 we saw a sustained trend in
the use of custom-made sample environments, allowing the study of ever more complex systems. For example, a new confinement sample cell
for the reflectometer FIGARO and the small-angle scattering instrument D22 has been commissioned. Additionally, a project to combine
neutron reflectometry with infrared spectroscopy and ellipsometry was approved by the College. Recently, microfluidic-SANS measurements have been performed on D22. This opens up the possibility of using SANS as a fast and efficient tool for screening large areas of the phase diagram in complex multicomponent systems. This will be very useful for industrial applications, where a quick overview of many different sample compositions is often required. Soft matter experiments continue to benefit from the facilities provided by the Partnership for Soft Condensed Matter (PSCM) which allow users to obtain a preliminary characterisation of their samples, thereby ensuring optimal use of their neutron beamtime.
More information on the support facilities cited here can be found on p.106.
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