A superbright X-ray laboratory microsource empowered by a novel restoration algorithm

The properties of nanoscale materials vary with the size and shape of the building blocks, which can be measured by (grazing-incidence) small-angle X-ray scattering along with the mutual positions of the nanoparticles. The accuracy in the determination of such parameters is dependent on the signal-to-noise ratio of the X-ray scattering pattern and on the visibility of the interference fringes. Here, a first-generation-synchrotron-class X-ray laboratory microsource was used in combination with a new restoration algorithm to probe nanoscale-assembled superstructures. The proposed algorithm, based on a maximum likelihood approach, allows one to deconvolve the beam-divergence effects from data and to restore, at least partially, missing data cut away by the beam stopper. It is shown that the combination of a superbright X-ray laboratory microsource with the data-restoring method allows a virtual enhancement of the instrument brilliance, improving signal-to-noise ratio and fringe visibility and reaching levels of performance comparable to third-generation synchrotron radiation beamlines.

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Neutron Scattering in Materials Science: Small-Angle Neutron Scattering Studies of Polymers

MRS Bulletin ◽

10.1557/s0883769400058395 ◽

1990 ◽

Vol 15 (11) ◽

pp. 73-77

Author(s):

George D. Wignall ◽

Frank S. Bates

Keyword(s):

Neutron Scattering ◽

Small Angle ◽

Small Angle Neutron Scattering ◽

Signal To Noise Ratio ◽

Signal To Noise ◽

X Ray ◽

X Ray Scattering ◽

Bulk Polymers ◽

Noise Ratio ◽

Ray Scattering

Before the application of small-angle neutron scattering (SANS) to the study of polymer structure, chain conformation studies were limited to light scattering and small-angle x-ray scattering (SAXS) techniques. These experiments were usually conducted in dilute solution, and the methodology to measure radii of gyration, virial coefficients, molecular weights, etc., was well established in the classical works of Guinier, Zimm, Debye and Kratky, who pioneered these techniques during the 1940s and 1950s. This methodology could not be applied to concentrated solutions or bulk polymers because of the difficulty of separating the intra- and inter-molecular components of the scattering function. One attempt to circumvent this difficulty was the experiment by Krigbaum and Godwin, who end-labeled polystyrene molecules with Ag atoms. When dispersed in unlabeled polystyrene, the excess x-ray scattering could in principle be analyzed to provide the end-to-end distance, though in practice the signal-to-noise ratio of the experiment was insufficient for accurately determining this parameter. To our knowledge the first suggestion to use the difference in coherent scattering lengths of deuterium (bD = 0.66 × 10−12cm) and hydrogen (bH = −0.37 × 10−12cm) to create scattering contrast between deuterated and normal (hydrogenous) molecules and provide a direct determination of molecular dimensions was made independently by at least two groups in the late 1960s. By deuterating the whole molecule, as opposed to end-labeling, this proposal increased the signal-to-noise ratio of the experiment by several orders of magnitude and made possible for the first time the practical analysis of molecular conformations in bulk polymers. Even so, such experiments could not be undertaken until the completion in Europe of the first instruments employing long wavelength neutrons and large distances between the entrance slit, sample and detector, which allowed deuterium labeling methods to be successfully applied to polymers in the early 1970s.

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Grazing incidence small angle X-ray scattering from nanoparticles: beyond classical analysis approximations

Acta Crystallographica Section A Foundations of Crystallography ◽

10.1107/s0108767305082607 ◽

2005 ◽

Vol 61 (a1) ◽

pp. c411-c411

Author(s):

R. Lazzari ◽

G. Renaud ◽

F. Leroy

Keyword(s):

Small Angle ◽

Grazing Incidence ◽

Classical Analysis ◽

X Ray ◽

X Ray Scattering ◽

Ray Scattering

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Strain Analysis in Thin La1−xCaxMnO3 Films by Grazing Incidence X-ray Scattering

MRS Proceedings ◽

10.1557/proc-602-195 ◽

1999 ◽

Vol 602 ◽

Author(s):

M. Petit ◽

L. J. Martinez-Miranda ◽

M. Rajeswari ◽

A. Biswas ◽

D. J. Kang ◽

...

Keyword(s):

Film Thickness ◽

Lattice Mismatch ◽

Compressive Strain ◽

Strain Analysis ◽

Grazing Incidence ◽

Relaxation Processes ◽

Near Surface ◽

X Ray ◽

X Ray Scattering ◽

Ray Scattering

AbstractWe have performed depth profile analyses of the lattice parameters in epitaxial thin films of La1−xCaxMno3 (LCMO), where x = 0.33 or 0.3, to understand the evolution of strain relaxation processes in these materials. The analyses were done using Grazing Incidence X-ray Scattering (GIXS) on films of different thicnesses on two different substrates, (100) oriented LaAlO3 (LAO), with a lattice mismatch of ∼2% and (110) oriented NGO, with a lattice mismatch of less than 0.1%. Films grown on LAO can exhibit up to three in-plane strained lattice constants, corresponding to a slight orthorhombic distortion of the crystal, as well as near-surface and columnar lattice relaxation. As a function of film thickness, a crossover from a strained film to a mixture of strained and relaxed regions in the film occurs in the range of 700 Å. The structural evolution at this thickness coincides with a change in the resistivity curve near the metalinsulator transition. The in-plane compressive strain has a range of 0.2 – 1.5%, depending on the film thickness for filsm in the range of 400 - 1500 A.

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