Interaction of a biosurfactant, Surfactin with a cationic Gemini surfactant in aqueous solution.

The interaction between biosurfactant Surfactin and cationic Gemini surfactant ethanediyl-1,3-bis(dodecyldimethylammonium bromide) (abbreviated as 12-3-12) was investigated using turbidity, surface tension, dynamic light scattering (DLS) and small angle neutron scattering (SANS). Analysis of critical micelle concentration (CMC) values in Surfactin/12-3-12 mixture indicates that there is synergism in formation of mixed Surfactin/12-3-12 micelles. Although Surfactin and 12-3-12 are oppositely charged in phosphate buffer solution (PBS, pH7.

Complex chiral modulations in FeGe close to magnetic ordering.

We report on detailed polarized small-angle neutron scattering on cubic FeGe in magnetic fields applied either along (transverse) the scattering vector or parallel (longitudinal) to the neutron beam. The (H, T) phase diagrams for all principal axes contain a segmented A-phase region just below the onset of magnetic order. Hexagonal Bragg-spot patterns were observed across the entire A-phase region for the longitudinal geometry.

SANS analysis of opal structures made by the capillary deposition method.

Small angle neutron scattering (SANS) is used to analyze the structure of opals and inverse opals made by the capillary deposition method. We show that there is no deformation in special lattice directions such as the growth direction and the support plane direction. However, effects of twinning of the dense-packed structure and plane-like lattice perturbations have been observed.

Neutron optical beam splitter from holographically structured nanoparticle-polymer composites.

We report a breakthrough in the search for versatile diffractive elements for cold neutrons. Nanoparticles are spatially arranged by holographical means in a photopolymer. These grating structures show remarkably efficient diffraction of cold neutrons up to about 50% for effective thicknesses of only 200   μm.

Grain-boundary-induced spin disorder in nanocrystalline gadolinium.

Based on experimental magnetic-field-dependent neutron scattering data, we have calculated the autocorrelation function of the spin misalignment of nanocrystalline (160)gadolinium. The analysis suggests the existence of two characteristic length scales in the spin system: the smaller one is about 5 nm and is attributed to the defect cores of the grain boundaries, whereas the larger length scale is of the order of the average crystallite size D = 21 nm and presumably describes the response of the magnetization to the magnetic anisotropy field of the individual crystallites.

Crystal handedness and spin helix chirality in Fe1-xCoxSi.

We show, with the help of polarized neutrons, that the cubic magnets Fe1-xCoxSi with Dzyaloshinskii-Moriya interaction can be switched between left (for x=0.1, 0.15) and right (for x=0.

Small-angle neutron scattering of nanocrystalline terbium with random paramagnetic susceptibility.

We report magnetic small-angle neutron scattering (SANS) data for the nanocrystalline rare earth metal Terbium in its paramagnetic state. Whereas critical scattering dominates at large momentum transfer, q, the (magnetic-) field response of the scattering at small q arises from the spatial nonuniformity of the paramagnetic susceptibility tensor. The finding of an interrelation between SANS and the susceptibility suggests a way for characterizing the nonuniform magnetic interactions in hard magnets by neutron scattering.

Local structure of a phase-separating binary mixture in a mesoporous glass matrix studied by small-angle neutron scattering.

The mesoscopic structure of the binary system isobutyric acid + heavy water (D(2)O) confined in a porous glass (controlled-pore silica glass, mean pore width ca. 10 nm) was studied by small-angle neutron scattering at off-critical compositions in a temperature range above and below the upper critical solution point. The scattering data were analyzed in terms of a structure factor model similar to that proposed by Formisano and Teixeira [Eur.

De-mixing dynamics of a binary liquid system in a controlled-pore glass. A neutron spin-echo spectroscopy and small angle neutron scattering study.

The temperature-induced microphase separation of the binary liquid system iso-butyric acid+heavy water (iBA + D(2)O) in a mesoporous silica glass (CPG-10-75) of nominal pore width 7.5 nm was investigated by neutron spin-echo spectroscopy (NSE) and neutron small-angle scattering (SANS). Two mixtures of different composition were studied at different scattering angles at temperatures above and below the bulk phase transition temperature.