2D reflectometry for the investigation of polymer interfaces: off-specular neutron scattering.

Specular and off-specular neutron reflectometry have been used in a combined approach to study thin polymer films. Our goal in this work is to illustrate the power of the off-specular scattering technique to probe the properties of the buried interface of immiscible polymer bilayers of deuterated polystyrene and protonated poly(methyl methacrylate) (h-PMMA). The diffuse scattering stemming from these systems is discussed in relation to thermal fluctuations at the polymer/polymer interface, providing a means to extract in-plane correlation lengths from buried interfaces.

Artificial Magnetic Pattern Arrays Probed by Polarized Neutron Reflectivity.

Traditionally, neutron scattering is an essential method for the analysis of spin structures and spin excitations in bulk materials. Over the last 30 years, polarized neutron scattering in terms of reflectometry has also contributed largely to the analysis of magnetic thin films and magnetic multilayers. More recently it has been shown that polarized neutron reflectivity is, in addition, a suitable tool for the study of thin films laterally patterned with magnetic stripes or islands.

Magnetic Structure of Ion-Beam Imprinted Stripe Domains Determined by Neutron Scattering.

We present a detailed analysis of the in-plane magnetic vector configuration in head-to-head/tail-to-tail stripe domain patterns of nominal 5 µm width. The patterns have been created by He-ion bombardment induced magnetic patterning of a CoFe/IrMn exchange bias thin-film system. Quantitative information about the chemical and magnetic structure is obtained from polarized neutron reflectometry (PNR) and off-specular scattering (OSS).

Nuclear Spin Incoherent Neutron Scattering from Quantum Well Resonators.

We report the detection and quantification of nuclear spin incoherent scattering from hydrogen occupying interstitial sites in a thin film of vanadium. The neutron wave field is enhanced in a quantum resonator with magnetically switchable boundaries. Our results provide a pathway for the study of dynamics at surfaces and in ultrathin films using inelastic and/or quasielastic neutron scattering methods.

Revealing the mechanism of passive transport in lipid bilayers via phonon-mediated nanometre-scale density fluctuations.

The passive transport of molecules through a cell membrane relies on thermal motions of the lipids. However, the nature of transmembrane transport and the precise mechanism remain elusive and call for a comprehensive study of phonon excitations. Here we report a high resolution inelastic X-ray scattering study of the in-plane phonon excitations in 1,2-dipalmitoyl-sn-glycero-3-phosphocholine above and below the main transition temperature.

Self assembly of magnetic nanoparticles at silicon surfaces.

Neutron reflectometry was used to study the assembly of magnetite nanoparticles in a water-based ferrofluid close to a silicon surface. Under three conditions, static, under shear and with a magnetic field, the depth profile is extracted. The particles have an average diameter of 11 nm and a volume density of 5% in a D2O-H2O mixture.

In-plane correlations in a polymer-supported lipid membrane measured by off-specular neutron scattering.

Polymer-supported single lipid bilayers are models to study configurations of cell membranes. We used off-specular neutron scattering to quantify in-plane height-height correlations of interfacial fluctuations of such a lipid bilayer. As temperature decreased from 37 °C to 25 °C, the polymer swells and the polymer-supported lipid membrane deviates from its initially nearly planar structure.

Development and application of setup for ac magnetic field in neutron scattering experiments.

We report on a new setup developed for neutron scattering experiments in periodically alternating magnetic fields at the sample position. The assembly consisting of rf generator, amplifier, wide band transformer, and resonance circuit. It allows to generate homogeneous ac magnetic fields over a volume of a few cm(3) and variable within a wide range of amplitudes and frequencies.