Neutron scattering length determination by means of total scattering

2018 ◽  
Vol 51 (3) ◽  
pp. 854-866 ◽  
Author(s):  
Alex C. Hannon ◽  
Alexandra S. Gibbs ◽  
Hidenori Takagi
Keyword(s):  
Correlation Function ◽  
Neutron Diffraction ◽  
Neutron Scattering ◽  
Cross Sections ◽  
Scattering Length ◽  
Neutron Diffraction Pattern ◽  
Average Density ◽  
A Value ◽  
Oxide Crystal ◽  
Scattering Lengths

A new method for the measurement of bound coherent neutron scattering lengths is reported. It is shown that a relative measurement of the neutron scattering length, {\overline b}, of an element can be made by analysis of the neutron correlation function of a suitable oxide crystal powder. For this analysis, it is essential to take into account the average density contribution to the correlation function, as well as the contributions arising from distances between atoms in the crystal. The method is demonstrated and verified by analysis of the neutron correlation function for the corundum form of Al2O3, yielding a value {\overline b} = 3.44 (1) fm for Al, in good agreement with the literature. The method is then applied to the isotopes of iridium, for which the values of the scattering lengths were unknown, and which are difficult to investigate by other methods owing to the large cross sections for the absorption of neutrons. The neutron correlation function of a sample of Sr2IrO4 enriched in 193Ir is used to determine values {\overline b} = 9.71 (18) fm and {\overline b} = 12.1 (9) fm for 193Ir and 191Ir, respectively, and these are consistent with the tabulated scattering length and cross sections of natural Ir. These values are of potential application for obtaining improved neutron diffraction results on iridates by the use of samples enriched in 193Ir, so that the severe absorption problems associated with 191Ir are avoided. Rietveld refinement of the neutron diffraction pattern of isotopically enriched Sr2IrO4 is used to yield a similar result for Ir. However, in practice the Rietveld result is shown to be less reliable because of correlation between the parameters of the fit.

The crystal structure of tricaesium tetrabromocobaltate(II) bromide, Cs3CoBr5, at 4.2 K by neutron diffraction

1981 ◽  
Vol 34 (12) ◽  
pp. 2495 ◽  
Author(s):  
BN Figgis ◽  
PA Reynolds
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Neutron Scattering ◽  
Single Crystal ◽  
Bond Length ◽  
Least Squares ◽  
Metal Ion ◽  
Scattering Length ◽  
Scattering Lengths ◽  
The Stability

The crystal structure of Cs3CoBr5 [I4/mcm, a 946(1), c 1504(2) pm, U 1.346(7) nm3, Z 4] has been determined at 4.2 K by single-crystal neutron diffraction methods. The Co-Br bond length is 239.8(2) pm, and the Br-Co-Br angles of the distorted tetrahedral cobalt environment are 107.58(9) and 110.43(9)�. The neutron scattering lengths of cobalt and bromine were found, by least-squares refinement, to be 2.46(2) × 10-15 and 6.78(2) × 10-15 m respectively, relative to a caesium scattering length of 5.38 × 10-l5 m. The contact distances and thermal parameters of Cs3CoBr5, when compared with those from Cs3CoCl5, provide further evidence on the stability of M3CoX5 salts. The metal ion must be sufficiently large to adequately fill the large holes in the lattice whose size is determined by X-...X- contacts.

Neutron diffraction, inelastic scattering and the structure of amphiphiles and macromolecules in solution

1975 ◽  
Vol 345 (1640) ◽  
pp. 119-144 ◽  
Keyword(s):  
Neutron Diffraction ◽  
Inelastic Scattering ◽  
Cross Sections ◽  
Biological Molecules ◽  
Variation Method ◽  
Contrast Variation ◽  
Structure And Dynamics ◽  
Spin Resonance ◽  
Scattering Lengths ◽  
Scattering Cross Sections

The methods by which neutron diffraction and inelastic scattering may be used to study the structure and dynamics of solutions are reviewed, with particular reference to solutions of amphiphile and biological molecules in water. Neutron methods have particular power because the scattering lengths for protons and deuterons are of opposite sign, and hence there exists the possibility of obtaining variable contrast between the scattering of the aqueous medium and the molecules in it. In addition, the contrast variation method is also applicable to inelastic scattering studies whereby the dynamics of one component of the solution can be preferentially studied due to large and variable differences in the scattering cross sections. Both applications of contrast variation are illustrated with examples of amphiphile-water lamellar mesophases, diffraction from collagen, viruses, and polymer solutions. Inelastic scattering observations and the dynamics of water between the lamellar sheets allow microscopic measurements of the water diffusion along and perpendicular to the layers. The information obtained is complementary to that from nuclear magnetic resonance and electron spin resonance studies of diffusion.

Neutron scattering lengths and cross sections of the barium isotopes

1985 ◽  
Vol 322 (1) ◽  
pp. 105-113 ◽  
Author(s):  
L. Koester ◽  
K. Knopf ◽  
W. Waschkowski
Keyword(s):  
Neutron Scattering ◽  
Cross Sections ◽  
Scattering Lengths

scholarly journals A search for deviations from the inverse square law of gravity at nm range using a pulsed neutron beam

2019 ◽  
Vol 219 ◽  
pp. 05002
Author(s):  
Christopher Haddock ◽  
Katsuya Hirota ◽  
Takashi Ino ◽  
Masaaki Kitaguchi ◽  
Kenji Mishima ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Cross Sections ◽  
Noble Gases ◽  
Scattering Length ◽  
Slow Neutron ◽  
Inverse Square Law ◽  
Scattering Cross ◽  
Law Of Gravity ◽  
Neutron Momentum ◽  
Scattering Cross Sections

Recently published results and ongoing experimental efforts to search for deviations from the inverse square law of gravity at the nanometer length scale using slow neutron scattering from the noble gases are discussed. Using the pulsed slow neutron beamline BL05 at the Materials and Life Sciences Facility at J-PARC, we measured the neutron momentum transfer (q) dependence of the differential scattering cross section for the noble gases He, Ne, Ar, Kr, and Xe. By comparing to the distributions obtained using pseudo-experimental Monte Carlo simulations and forming ratios between Xe and He, we placed an upper bound on the strength of a new interaction as a function of interaction length λ which improved upon previous results in the region λ < 0.1 nm, and remains competitive in the larger λ region. Additionally we describe how we are using our technique to extract relative values of the total neutron scattering cross sections of the noble gases, as well as how we plan to measure the neutron-electron scattering length using the NOVA instrument on BL21 at J-PARC.

scholarly journals Small Angle Neutron Scattering from Nanophase Titanium As A Function of Oxidation

1988 ◽  
Vol 132 ◽  
Author(s):  
J. A. Eastman ◽  
J. E. Epperson ◽  
H. Hahn ◽  
T. E. Klippert ◽  
A. Narayanasamy ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Scattering Length ◽  
Contrast Variation ◽  
Gas Condensation ◽  
Pressure Oxygen ◽  
Scattering Centers ◽  
Scattering Lengths ◽  
Contrast Matching

ABSTRACTNanophase titanium, prepared by the gas-condensation method both as aggregated powder and in lightly compacted discs, has been studied by conventional small angle neutron scattering, and by use of contrast variation methods. The contrast has been changed (a), isotopically, by means of deuterated/protonated solvents distilled into the specimen and (b) by progressive incremental oxidation of the Ti particles using fixed doses of low-pressure oxygen. It was shown that some evolution of the small angle pattern for lightly compacted nanophase Ti occurred over a period of several months at 300 K. Contrast matching by external solvent works well and has allowed the scattering lengths of oxidized and unoxidized specimens to be followed. The results imply that the scattering from metal and oxide can be separated under suitable conditions. The partial oxidation experiments indicate that there is both a fast and slow oxidation at 300 K. Also, during slow oxidation, high scattering length density scattering centers were formed whose number increased, but whose size remained the same at about 2 nm; these centers are tentatively assumed to be TiO2.

A study of α -resorcinol by neutron diffraction

1956 ◽  
Vol 235 (1203) ◽  
pp. 552-559 ◽  
Keyword(s):  
Hydrogen Bonds ◽  
Neutron Diffraction ◽  
Oxygen Atom ◽  
Neutron Scattering ◽  
Benzene Ring ◽  
Unit Cell ◽  
The Other ◽  
Aromatic Molecule ◽  
Hydrogen Atoms ◽  
A Value

The first study of an aromatic molecule by neutron diffraction, leading to a Fourier projection of the neutron scattering density in the unit cell, gives a value of 1·08 ± 0·04 Å for the length of the C—H bonds which link hydrogen atoms to the benzene ring. The spirals of hydrogen bonds which bind together neighbouring molecules are found to consist of typical ‘long bonds’, with the proton much closer to one oxygen atom than to the other. The O—H distance is 1·02 Å, and it appears that the O, H, O atoms are not collinear.

Evidence of bayerite clusters within the AAO amorphous bulk alumina. Consequence for AAO SANS matching properties.

2008 ◽  
Vol 1074 ◽  
Author(s):  
Karine Lagrené ◽  
Jean-Marc Zanotti
Keyword(s):  
Neutron Diffraction ◽  
Neutron Scattering ◽  
Porous Structure ◽  
Small Angle ◽  
Large Scale ◽  
Scattering Length ◽  
Synthesis Process ◽  
Important Input ◽  
Contrast Matching ◽  
Anodic Synthesis

ABSTRACTSmall Angle Neutron Scattering (SANS) and neutron diffraction are used to probe the structure of Anodized Aluminium Oxide (AAO) in an extended Q range, from 7.10−3 to 16 Å−1. In the small angle region [7. 10−3 Å−1 − 7. 10−2 Å−1], impregnation of a D2O/H2O mixture within the AAO porous structure, leads to a dramatic decrease of the coherent SANS signal by two orders of magnitude, but perfect matching of the membrane cannot be reached. We explain such an imperfect matching by the presence of 1 nm in size Bayerite domains within the bulk of the amorphous Al2O3 matrix, as detected by Neutron diffraction in the [0.3 Å−1 − 4 Å−1] Q range. Traces of sulfur, probably incorporated during the anodic synthesis process in a H2SO4 solution, are also detected by Scanning Electron Microscopy with Energy Dispersive X-ray analysis (SEM-EDX). We estimate the AAO neutron scattering length to be 4.22 1010 cm−2. This value is an important input, when taking advantage of neutron contrast matching to probe the large scale filling homogeneity (adsorption of a liquid or deposition of a solid) within the porous structure of AAO membranes.

Direct Measurement of the Hydrogen-Hydrogen Correlations in Hydrogenated Amorphous Ni56 Dy44 by Neutron Diffraction

1998 ◽  
Vol 53 (9) ◽  
pp. 766-770
Author(s):  
P. Lamparter ◽  
Ma. Nuding ◽  
S. Steeb ◽  
R. Bellissent
Keyword(s):  
Neutron Diffraction ◽  
Neutron Scattering ◽  
Melt Spinning ◽  
Scattering Length ◽  
Pair Correlation ◽  
Main Peak ◽  
Neutron Diffraction Experiment ◽  
Isotopic Mixture ◽  
Nearest Neighbours ◽  
Hydrogenated Amorphous

Abstract From an isotopic mixture of dysprosium with zero neutron scattering length and an isotopic mixture of nickel with zero neutron scattering length ribbons of the amorphous alloy Ni56 Dy44 were produced by melt-spinning and loaded with 59 at% deuterium. A neutron diffraction experiment yielded directly the deuterium-deuterium partial structure factor SDD and the partial pair correlation function GDD . The incorporation of the D-atoms into the amorphous matrix shows an ordering up to five coordination shells at least. The main peak of GDD is split up into a contribution at 2.36 Å with 5.4 nearest neighbours and a contribution at 2.76 Å with 4 neighbours. The D-atoms are located preferentially in Dy4 -tetrahedra, where the occupation of two neighbouring face-sharing tetrahedra is avoided.

Wechselwirkung von Neutronen mit Wolfram und seinen Isotopen

1987 ◽  
Vol 42 (9) ◽  
pp. 909-916 ◽  
Author(s):  
K. Knopf ◽  
W. Waschkowski
Keyword(s):  
Neutron Scattering ◽  
Cross Sections ◽  
Coherent Scattering ◽  
Total Cross Sections ◽  
Resonance Parameters ◽  
Scattering Lengths

The coherent neutron scattering lengths and total cross sections of elemental and oxide samples of natural and isotopically enriched W are determined. From these results the following coherent scattering lengths, b, and absorptions at 0.0253 eV, σγ were deduced:b (natW) = 4.86±0.02 fm, σγ = 17.3 ±0.5 b ,b (182W) = 7.04±0.04 fm, σγ = 19.6±0.3 b ,b (183W) = 6.59±0.04 fm, σγ = 10.5±0.2 b ,b (184W) = 7.55±0.06 fm, σγ = 1.7±0.1 b ,b (186W) = -0 .7 3±0.04 fm, σγ = 38.5 ±0.8 b .By comparison with the resonance parameters, the incoherence and the potential radii are derived and discussed. The bound level on W-182 must be fitted with a scattering width of gI0n = 161 meV at E0 = - 94 eV.

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