Inelastic neutron scattering sample preparation

N. Essayem, Y.Y. Tong, H. Jobic J.C. Vedrine (2000). Appl. Catal. A, 194/195, 109-122. Characterisation of the protonic sites in H3PW12O40 and Csi,9Hi,iPWi204o a solid-state H-1, H-2, P-31 MAS-NMR and inelastic neutron scattering study on samples prepared under reaction conditions.. 

CS1.9H1.1PW12O40 a solid-state H-1, H-2, P-31 MAS-NMR and inelastic neutron scattering study on samples prepared under standard reaction conditions. 

Fig. 23.3. Inelastic neutron scattering spectra of y-MnOj powder. The spectrum of the sample is recorded at 4 K and the spectrum of the same sample heated previously at 450 "C has been subtracted. Bonds are assigned to localized protons (OH .HjO) whereas the diffuse and broad continuum above 100cm seems related to a proton gap (proton lattice gap) (with courtesy ). The INS spectrum of Ho.ssMnOj prepared by chemical reduction of y-MnOj shows three peaks near 1120, 2200 and 3100 cm which are assigned to the 0 - 1, 0 - 2 and 0 — 3 transitions of an isotropic oscillator, respectively. This triplet may correspond to a non-specific bonded proton at the centre of the octahedral cavity .

Neutron Techniques. These include neutron diffraction (ND) and inelastic neutron scattering (INS). Both techniques provide complimentary structural information relative to XRD (44), since the sensitivity of the latter method is proportional to the number of electrons Z, whereas that of the neutron scattering is proportional to the nuclear cross section. Using neutrons makes it possible to detect light elements, such as deuterium, which has a large coherent scattering length In such a case, ND will be much more informative than XRD in the location of that element. In addition, ND allows a better discrimination between different elements with similar Z (45) and spin densities (46). When necessary, this contrast can even be enhanced by the use of specifically prepared samples with different isotopes (47). 

Vibrational spectroscopy is especially appropriate to investigate this type of system, since it allows the detection and characterization of both intra- and intermolecular interactions. It does not require any special sample preparation, thus avoiding mechanical influences which may alter the physicochemical properties of the drug-excipient formulation. Inelastic Neutron Scattering (INS), in particular, is quite suitable for the study of these kinds of interactions involving hydrogen atoms. 

PrPtBi Measurements were initially made on powder samples prepared by arc melting (Suzuki et al., 1997). The electrical resistivity ( 1 mf2cm at 300 K) and Hall coefficient ( 0.7 cm /C at low temperatures) are consistent with semiconductivity. The magnetic susceptibility follows the Curie-Weiss law above 50 K but tends to become temperature-independent below 50 K. The specific heat curve shows a prominent anomaly at 1.35 K. A crystalline electric field (CEF) level scheme was derived from inelastic neutron scattering... 

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