Larmor science
11 Sep 2009




What science can larmor do?


Many of the soft matter themes relevant to LOQ and SANS2D today will be extended to significantly longer length scales by SESANS, but retaining good count rates and the advantages of neutron contrast variation. For larger particles the shape of S(Q), or rather the long range correlations in g(z), are decoupled from the particle shape, allowing the nature of interactions (attractive or repulsive) and the local packing to be easily revealed. Thus SESANS would allow, for example, detailed studies of long-range structure and interparticle interactions in colloidal dispersions, foams, lamellar fragments, supramolecular conjugates, complex mixtures, composites, ‘templated’ and phase segregated systems. These have potential applications in areas such as photonics, drug delivery, gene therapy, catalysis, separation science, and next-generation materials.

An important factor here is that SESANS would provide information in real space allowing direct comparison with complementary results from conventional microscopy and imaging.

The ability, unlike microscopy, of SESANS to facilitate bulk averaging of particle size and interactions on micron scales in opaque samples may be of interest to the food processing industry. Dairy products are increasingly ‘engineered’, and cooking, freezing, enzyme degradation and the processing of starches all have physico-structural consequences for foodstuffs. Ice cream and chocolate are very complex systems indeed! Similarly, SESANS might provide important new insights into the transport of pollutants in the aquatic environment by providing a better understanding of the natural particles and agglomerates in soils, effluents and river sediments to which pollutants sorb. The porosity of rocks is also relevant to pollutant diffusion and to (oil) reservoir engineering. Both could be investigated by SESANS and MISANS.

Picosecond timescales are characteristic of the stochastic dynamics of simple and small liquids at thermodynamic equilibrium, and these are well within the reach of current neutron instrumentation. To explore the motions of larger entities, access to longer timescales is mandatory, and could be provided by NRSE & MIEZE Spectroscopy. Such motions are not only found in biomolecules, polymers, and supramolecular assemblies of nanometre dimensions, but also in metastable states of matter (glasses) or fluids under extreme confinement. In the latter case, much remains to be learnt about how dynamical properties such as viscosity or diffusitivity are modified by the confining substrate, as well as how this new paradigm in Materials Science will be exploited in the design of novel composite materials.

Below is a summary of some potential science areas that might be addressed by LARMOR:

Soft Matter & Complex Fluids:

  • SESANS: structure of concentrated colloids; studies of colloidal crystallisation, photonic crystals, emulsions, foams, lamellar fragments & liquid crystals; studies of segregation in polymer blends.
  • MIEZE: slow motions in macromolecular systems, including glass-forming polymers (for direct comparison to coarse-grained simulations); nanosecond correlations in ferrofluids.
  • MISANS: colloid dynamics; nanofluidics.
  • NRSE: reptation and diffusion in polymers; interfacial bending and deformation studies in microemulsions and micelles; studies of micellar exchange processes. 

Food Science:

  • SESANS: the physical chemistry underlying the cooking, freezing & digestion of dairy products; the structure of ice cream!
  • MISANS: the mechanisms of bio- and cryo-preservation.

Molecular Biology:

  • MIEZE: structure-mobility relationships in biomolecules.
  • MISANS: the kinetics & thermodynamics of enzyme activity.
  • MIEZE & MISANS: studies of cell membranes and their components, including lipid bilayers.

Bio-materials & Pharmacy:

  • SESANS: studies of giant vesicles and polymer-DNA conjugates.

Advanced Materials & Engineering:

  • SESANS: large-scale structural studies of composites, ceramics, semi-crystalline fibres, and templated silicalites/zeolites.
  • MIEZE: relaxation phenomena in polymer electrolyte materials; proton conduction in fuel-cell materials; studies of ferroelectric materials.
  • MISANS & Larmor Diffraction: transitions in shape-memory alloys.
  • Larmor Diffraction: residual stress studies; investigations of isobaric thermal expansion, isothermal compressibility, and dielectric hysteresis; measurement of elastic constants; temperature dependence of linewidths. 

Environmental & Earth Science:

  • SESANS: structure of soils and sediments; floc structure in aquatic colloids.
  • MIEZE: molecular mobility (viz microrheology) in nanoporous materials (e.g., clays).
  • MISANS: percolation studies.

Liquids & Glasses:

  • NRSE: dynamics of glasses.
  • MIEZE & MISANS: exploring the glass transition in dynamically arrested matter.

Magnetism & Superconductivity:

  • SESANS: structure of granular magnetic materials; flux-line lattices in superconductors.
  • MIEZE: fast magnetization processes in multilayered materials (spin valves, etc).
  • MISANS: ferrofluidics.
  • Larmor Diffraction: high-resolution magnetic diffraction.

Granular Materials:

  • SESANS: structure of powders.
  • MIEZE & MISANS: supramolecular chemistry.
  • MISANS: percolation in porous media.