関: small-angle X-ray scattering

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/11/26 09:43:45」(JST)

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Concepts common to small-angle X-ray scattering and small-angle neutron scattering are described in the overarching lemma small-angle scattering.

Small-angle X-ray scattering (SAXS) is a small-angle scattering (SAS) technique where the elastic scattering of X-rays (wavelength 0.1 ... 0.2 nm) by a sample which has inhomogeneities in the nm-range, is recorded at very low angles (typically 0.1 - 10°). This angular range contains information about the shape and size of macromolecules, characteristic distances of partially ordered materials, pore sizes, and other data. SAXS is capable of delivering structural information of macromolecules between 5 and 25 nm, of repeat distances in partially ordered systems of up to 150 nm.^[1] USAXS (ultra-small angle X-ray scattering) can resolve even larger dimensions.

SAXS and USAXS belong to a family of X-ray scattering techniques that are used in the characterization of materials. In the case of biological macromolecules such as proteins, the advantage of SAXS over crystallography is that a crystalline sample is not needed. Nuclear magnetic resonance spectroscopy methods encounter problems with macromolecules of higher molecular mass (> 30-40 kDa). However, owing to the random orientation of dissolved or partially ordered molecules, the spatial averaging leads to a loss of information in SAXS compared to crystallography.

Applications

SAXS is used for the determination of the microscale or nanoscale structure of particle systems in terms of such parameters as averaged particle sizes, shapes, distribution, and surface-to-volume ratio. The materials can be solid or liquid and they can contain solid, liquid or gaseous domains (so-called particles) of the same or another material in any combination. Not only particles, but also the structure of ordered systems like lamellae, and fractal-like materials can be studied. The method is accurate, non-destructive and usually requires only a minimum of sample preparation. Applications are very broad and include colloids of all types, metals, cement, oil, polymers, plastics, proteins, foods and pharmaceuticals and can be found in research as well as in quality control. The X-ray source can be a laboratory source or synchrotron light which provides a higher X-ray flux.

SAXS instruments

In an SAXS instrument a monochromatic beam of X-rays is brought to a sample from which some of the X-rays scatter, while most simply go through the sample without interacting with it. The scattered X-rays form a scattering pattern which is then detected at a detector which is typically a 2-dimensional flat X-ray detector situated behind the sample perpendicular to the direction of the primary beam that initially hit the sample. The scattering pattern contains the information on the structure of the sample. The major problem that must be overcome in SAXS instrumentation is the separation of the weak scattered intensity from the strong main beam. The smaller the desired angle, the more difficult this becomes. The problem is comparable to one encountered when trying to observe a weakly radiant object close to the sun, like the sun's corona. Only if the moon blocks out the main light source does the corona become visible. Likewise, in SAXS the non-scattered beam that merely travels through the sample must be blocked, without blocking the closely adjacent scattered radiation. Most available X-ray sources produce divergent beams and this compounds the problem. In principle the problem could be overcome by focusing the beam, but this is not easy when dealing with X-rays and was previously not done except on synchrotrons where large bent mirrors can be used. This is why most laboratory small angle devices rely on collimation instead. Laboratory SAXS instruments can be divided into two main groups: point-collimation and line-collimation instruments:

Point-collimation instruments have pinholes that shape the X-ray beam to a small circular or elliptical spot that illuminates the sample. Thus the scattering is centro-symmetrically distributed around the primary X-ray beam and the scattering pattern in the detection plane consists of circles around the primary beam. Owing to the small illuminated sample volume and the wastefulness of the collimation process — only those photons are allowed to pass that happen to fly in the right direction — the scattered intensity is small and therefore the measurement time is in the order of hours or days in case of very weak scatterers. If focusing optics like bent mirrors or bent monochromator crystals or collimating and monochromating optics like multilayers are used, measurement time can be greatly reduced. Point-collimation allows the orientation of non-isotropic systems (fibres, sheared liquids) to be determined.
Line-collimation instruments confine the beam only in one dimension so that the beam profile is a long but narrow line. The illuminated sample volume is much larger compared to point-collimation and the scattered intensity at the same flux density is proportionally larger. Thus measuring times with line-collimation SAXS instruments are much shorter compared to point-collimation and are in the range of minutes. A disadvantage is that the recorded pattern is essentially an integrated superposition (a self-convolution) of many pinhole adjacent pinhole patterns. The resulting smearing can be easily removed using model-free algorithms or deconvolution methods based on Fourier transformation, but only if the system is isotropic. Line collimation is of great benefit for any isotropic nanostructured materials, e.g. proteins, surfactants, particle dispersion and emulsions.

References

^ Glatter O, Kratky O, ed. (1982). Small Angle X-ray Scattering. Academic Press. ISBN 0-12-286280-5.

External links

Your portal to SAXS nanostructure analysis
The Small Angle Scattering Portal
SAXS at a Synchrotron
Looking At Nothing, a weblog about SAXS with much supplementary and introductory material
A movie explaining the workings of a pinhole collimated SAXS apparatus
A movie explaining the workings of a slit collimated SAXS apparatus
A movie demonstrating small-angle scattering using laserlight on a hair
Small-angle scattering special interest group at the Advanced Photon Source, Argonne National Laboratory, USA

List of SAXS beamlines

Risø, SAXS beamline Roskilde, Denmark
SAXS/WAXS Beamline, Australian Synchrotron Melbourne, Australia
SAXS/D, SSRL Beamline 4-2, SLAC USA
SAXS/WAXS-Non Crystalline Diffraction Beamline (NCD)-Sincrotrón ALBA, Cerdanyola del Vallès Spain
SAXS/WAXS/GISAXS Beamline, Advanced Light Source 7.3.3, LBNL USA
SAXS endstation at the SIBYLS Beamline, Advanced Light Source 12.3.1 USA
SAXS1 and SAXS2 beamlines at Brazilian Synchrotron Light Laboratory Brazil
ID02 SAXS/WAXS/USAXS beamline Grenoble, France
BM29 BioSAXS beamline Grenoble, France
SWING Beamline at Synchrotron SOLEIL Saint-Aubin, France
P12 Beamline at DESY (PETRA III) Hamburg, Germany
BL9 beamline of DELTA, Technical University of Dortmund Germany
SAXS Beamline at Elettra Trieste, Italy
cSAXS beamline, Swiss Light Source Villigen, Switzerland
I22 beamline at Diamond Light Source, Harwell Science & Innovation Campus England, UK
APS USAXS instrument, Advanced Photon Source, Argonne National Laboratory USA
BNL SAXS/WAXS X9 beamline, National Synchrotron Light Source, Brookhaven National Laboratory USA
D1 beamline (GISAXS/GIWAXS/SAXS), CHESS Cornell University USA
G1 beamline (SAXS/BioSAXS/GISAXS), CHESS Cornell University USA
SaxsWaxs, BM26B Dutch-Belgian beamline at ESRF Grenoble, France
3C, 4C, and 9A beamlines at PAL (SAXS I, SAXS II, and U-SAXS), POSTECH, Pohang, South Korea
I911-SAXS beamline, MAX IV Laboratory Lund, Sweden
APS CMS group (12-BM, 12-ID-B and 12-ID-C), Argonne National Laboratory IL, USA

SAXS Instrument Manufacturers

Anton Paar GmbH, Austria
Bruker AXS, Germany
Hecus X-Ray Systems Graz, Austria
PANalytical. The Netherlands
Rigaku Corporation, Japan
Xenocs, France
Saxslab, Denmark

English Journal

Comparative study of the AT(1) receptor prodrug antagonist candesartan cilexetil with other sartans on the interactions with membrane bilayers.

Fotakis C, Megariotis G, Christodouleas D, Kritsi E, Zoumpoulakis P, Ntountaniotis D, Zervou M, Potamitis C, Hodzic A, Pabst G, Rappolt M, Mali G, Baldus J, Glaubitz C, Papadopoulos MG, Afantitis A, Melagraki G, Mavromoustakos T.SourceChemistry Department, National and Kapodistrian University of Athens, Panepistimioupolis Zographou 15771, Greece; Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, Vas. Constantinou 48, Athens 11635, Greece.
Biochimica et biophysica acta.Biochim Biophys Acta.2012 Dec;1818(12):3107-20. doi: 10.1016/j.bbamem.2012.08.009. Epub 2012 Aug 18.
Drug-membrane interactions of the candesartan cilexetil (TCV-116) have been studied on molecular basis by applying various complementary biophysical techniques namely differential scanning calorimetry (DSC), Raman spectroscopy, small and wide angle X-ray scattering (SAXS and WAXS), solution (1)H and
PMID 22906712

Molecular and rheological characterization of carrageenan solutions extracted from Kappaphycus alvarezii.

Webber V, de Carvalho SM, Barreto PL.SourceDepartamento de Ciência e Tecnologia de Alimentos, Centro de Ciências Agrárias, Universidade Federal de Santa Catarina, Rod. Admar Gonzaga, 1346 Itacorubi, 88034-001 Florianópolis, SC, Brazil.
Carbohydrate polymers.Carbohydr Polym.2012 Nov 6;90(4):1744-9. Epub 2012 Jul 31.
This study evaluates and relates the molecular and rheological characteristics of native carrageenan obtained from Kappaphycus alvarezii seaweed. Native carrageenan was extracted by a differentiated methodology by atomization drying process, which reduces the time for obtaining carrageenan dry powde
PMID 22944442

Japanese Journal

Stability Conditions and Mechanism of Cream Soaps : Effect of Polyols

Sagitani Hiromichi,Komoriya Masumi
Journal of Oleo Science 64(8), 809-816, 2015-08
NAID 40020534900

β-1,3-グルカンを用いた薬物送達システムへの応用

Maegawa Yoshiya,Mochizuki Shinichi,Miyamoto Noriko [他]
Trends in glycoscience and glycotechnology 27(153-155), 13-29, 2015-01
NAID 40020571540

X線散乱法を用いた凝集粒子の構造評価

森康維,宮本竜馬,土屋活美 [他],Babick Frank,Stintz Michael,Steffen Werner,Butt Hans-Jürgen
同志社大学理工学研究報告 55(4), 335-340, 2015-01
… In this paper, we examined the fractal dimension analysis using small angles X-ray scattering (SAXS) could be useful to evaluate the structure of aggregated NPs. … The fractal dimension could be obtained by the scattering data by SAXS with the scaling approach. …
NAID 120005641783