Home  About us  Contact
 

Polarized Neutrons (polarized + neutron)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

The electron-spin,nuclear-spin interaction studied by polarized neutron scattering

ACTA CRYSTALLOGRAPHICA SECTION A, Issue 6 2007
Heinrich B. Stuhrmann
Dynamic nuclear spin polarization (DNP) is mediated by the dipolar interaction of paramagnetic centres with nuclear spins. This process is most likely to occur near paramagnetic centres at an angle close to 45° with respect to the direction of the external magnetic field. The resulting distribution of polarized nuclear spins leads to an anisotropy of the polarized neutron scattering pattern, even with randomly oriented radical molecules. The corresponding cross section of polarized coherent neutron scattering in terms of a multipole expansion is derived for radical molecules in solution. An application using data of time-resolved polarized neutron scattering from an organic chromium(V) molecule is tested. [source]

Study of ferrite ferrofluids by small-angle scattering of polarized neutrons

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2007
Massimo Bonini
Nanoparticles consisting of a magnetic core (Fe3O4, CoFe2O4 and CuFe2O4) and a hydrophobic shell were prepared by chemical co-precipitation of the inorganic cores and by subsequently modifying the surface with dodecanoic acid. The nanoparticles were then dispersed in cyclohexane to form stable ferrofluids. These dispersions were investigated by small-angle scattering of polarized neutrons and the data were interpreted according to a `pearl-necklace' model, opportunely modified to account for the core,shell structure of the particles. Results of the fitting show that the particles consist of a magnetic core with a mean radius of 40,50,Å and an organic shell with a thickness of 7,8,Å. These nanoparticles assemble in fractal aggregates when a magnetic field is applied. [source]

Spin-echo small-angle neutron scattering in neutron reflectometry

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 6 2003
M. Theo Rekveldt
A new method to perform neutron reflectometry measurements is discussed. The method is based on Larmor precession of polarized neutrons in the spin-echo mode. Two different modes of application are discussed, giving successively information about the structure perpendicular to and parallel to the sample plane. After describing the method, simulated results of the perpendicular mode are compared with those obtained by conventional neutron reflectometry methods. In this comparison, first the results obtained by the SESANS method are translated to those obtained by conventional methods. After that, more specific applications of the new method are considered. In the comparison, attention is focused on measuring statistics and resolution as readily comparable quantities. [source]