Neutron Scattering In Colloid Science
Because of the intrinsically small size of particles found in colloids, it is difficult to determine the molecular organisation within them. This is an important aspect when studying relationships between physical properties and molecular structure. However, information on the molecular organistation can still be obtained if small enough particles probe a colloidal system, i.e. they interact with the system, and as a result they are scattered. Scattering techniques provide the most obvious methods for obtaining quantitative information on size, shape and structure of colloidal particles, since they are based on interactions between incident radiation (e.g., light, X-ray or neutrons) and particles. The size range of micelles, microemulsions, or other typical colloidal particles is approximately 10 – 104 Å, so valuable information can be obtained if the incident wavelength, λ, falls within this range. Therefore, microemulsion droplets or micelles, in the order of 102 Å in size, can be characterized by beams of X-rays (λ = 0.5 – 2.3 Å) and neutrons (λ = 0.1 – 30 Å), while for larger colloidal particles, light scattering (λ = 4000 – 8000 Å) can be used.
Neutron scattering techniques provide the ideal tools for studying colloidal systems as the size of the aggregates and particles often fall within the resolution offered by neutrons. Here in the Eastoe group we make extensive use of neutron scattering facilities and regularly visit two of the most heavily subscribed institutes in the world (the Institut Laue-Langevin (ILL) in Grenoble, France, and the ISIS Facility at the Rutherford Appleton Laboratory in Didcot, U.K.).
These sections provide some brief details about the institutes and the sort of techniques we commonly use for our experiments on these field trips.