When To Utilize SAXS Everything You Ever Wanted To Know .
Everything You Ever Wanted to Know AboutWhenXtoUtilizeSAXSSButWereAfraidto AskASJohn A PopleStanford Synchrotron Radiation Laboratory,Stanford Linear Accelerator Center, Stanford CA 94309
When should I use theScattering Technique?
Ideal Studies for ScatteringScattering good for: Global parameters,distributions; 1st order Different sample states In-situ transitional studies Non destructive samplepreparationSolidMelted & ShearedRecrystallized
Ideal Studies for MicroscopyMicroscopy good for: Local detail Surface detail Faithfully representslocal complexitiesE.g. if objective is tomonitor the degree towhich Mickey’s nose(s)and ears hold to a circularmicromorphology usemicroscopy not scattering
Complementary Scattering and MicroscopyAg-Au dealloyed in 70% HNO 35 minsin concHNO31 min5 min15 min60 min720 min1000.00100.00200 nm60 minsL o g In t10.001.000.010.10.100.01Log Q1Forming a bi-continuousporous network withligament width on thenanoscale by removingthe less noble elementfrom a binary alloy, inthis case Ag-Au
Scattering: Neutrons or Photons?X-raysSensitive to electron densitycontrastNeutronsSensitive to nuclearscattering length contrastNeutron scattering: Deuteration allows species selectionAdvantages of X-ray scattering: Relatively small sample quantities required Relatively fast data acquisition times - allows timeresolved effects to be characterized
Scattering: Neutrons or Photons?Neutrons: Deuteration allows species selectionThis essentially permits a dramaticalteration to the ‘visibility’ of the taggedelements in terms of their contribution tothe reciprocal space scattering patternAtom1H2DScattering length Incoherent scattering(x 1012 cm2)(x 1024 cm2)-0.374800.6672
Scattering: Neutrons or Photons?Photos of deformationSANS patternsλ 0%λ 300%
Scattering: Neutrons or Photons?X-rays:Order of magnitude better spatial resolutionFast data acquisition times for time resolved dataOscillatory Shearing of lyotropic HPC – a liquid crystal polymer
X-ray Scattering: Transmission or Reflection?Need to be conscious of:Constituent elements, i.e. absorption cutoffsMultiple scatteringArea of interest: surface effect or bulk effectTransmission geometry appropriatefor: Extracting bulk parameters,especially in deformation Weakly scattering samples:can vary path length
X-ray Scattering: Transmission or Reflection?Reflection geometry appropriate for: Films on a substrate (whether opaque or not) Probing surface interactions
X-ray Scattering: SAXS or WAXS?No fundamental difference in physics: a consequence of chemistryWAXS patterns contain dataconcerning correlations on an intramolecular, inter-atomic level (0.1-1 nm)SAXS patterns contain data concerningcorrelations on an inter-molecular level:necessarily samples where there ismacromolecular or aggregate order(1-100 nm)As synthesis design/control improves,SAXS becomes more relevant thanever before
X-ray Scattering: SAXS or WAXS?Experimental consequencesWAXS: Detector close to sample, consider: Distortion of reciprocal space mapping Thermal effects when heating sample No ion chamber for absorptionSAXS: Detector far from sample, consider: Absorption from intermediate space Interception of appropriate q range
What can I Learn from aSAXS Pattern?
Recognizing Reciprocal Space Patterns: IndexingFace centered cubic pattern from diblock copolymer gel
Recognizing Reciprocal Space Patterns: IndexingRealspacepackingFace centered cubicBody centered ns)Normalized 1; 4/3; 8/3peak positions 1; 2; 3 1; 3; 4
Recognizing Reciprocal Space Patterns: RgJames L HedrickIBM Almaden, 650 Harry Road,San Jose, CA 95120F 48D 53E 45A 51Dendrimers designedas poragens for nanoporous media: interestin monodispersity anddensity distribution perporagenC 42B 50Rg2 α ln I(q) / q2
Modeling Radial Density of Isomer ArchitecturesRelate the internal density (and thus functionality as nano-electronicapplication) of dendrimer isomer to the design architecture, modelling asa star with f arms. Can predict size and density of sphere fromarchitectural model.FModel:Dρ(r) f (3ν-1)/2ν r (1-3ν)/ν dr0.8ERg/RhCABC0.5EBF DA1/ρ
Recognizing Reciprocal Space Patterns:Preferential imagealigned rodsPreferentiallyaligned rodsHydrated DNA
Extracting Physical Parameters from X-ray dataqφI(q)I(φ)qφ
Extracting Physical Parameters from X-ray dataln I(q)Molecular size: Radius of gyration (Rg)I(q) I(0) exp [-q2Rg2 / 3]q2Guinier plotRg2 α ln I(q) / q2Guinier region: q 1 / Rg
Extracting Physical Parameters from X-ray dataMolecular conformation: Scaling exponentln I(q)Guinier plateauIntermediateregionln qGradient of profile inintermediate regionimplies fractal dimensionof scattering unitRodq-1Coil ingood solventq-5/3Sphereq-4
Molecular Conformation in DentinJohn H KinneyDepartment of Preventive and Restorative Dental Sciences,University of California, San Francisco, CA 94143qΘDEJpulpSAXS pattern
Molecular Conformation in Dentin2.216G21316G224Scaling exponent217G2461.81.61.41.2100.511.5Distance from pulp (mm)2
Molecular Conformation in DentinScaling exponentShape change of mineral crystallites from needle-like to plate-like from pulp todentin-enamel junction 11.52Distance from pulp (mm)35330Dentinogenesis imperfecta (DI) teethshown to exhibit impaired developmentof intrafibrillar mineral: characteristicscattering peaks are absent from thediseased tooth.I(q)2520Control tooth4 5615310DI tooth5000.20.4q / nm-10.60.8
Extracting Physical Parameters from X-ray dataMolecular conformation: Persistence length of coiled chainI(q) q2Kratky plotq*qpersistence length 6 / (π q*)
Extracting Physical Parameters from X-ray dataMolecular orientation: Orientation parameter P2 P2n(cos φ) I(s,φ) P2n(cos φ) sin φ dφ I(s,φ) sin φ dφI(φ)Normalized:-0.5 P2 1qφ00Azimuthal profileφ
Molecular Orientation in Injection MoldingsMeasuring the degree and inclination of preferential molecularorientation in a piece of injection molded plastic (e.g. hip replacementjoints). 1500 WAXS patternsMarks the injection pointOrientation parameters: 0 P2 0.3Axis of orientation
What can the SAXS beamlineat SSRL do?
GENERIC SYNCHROTRON LAYOUTLINACRadius 5mE 2.5GeVhνE 0.01GeVe-BOOSTERSTORAGERINGRadius 10mE 3 GeVI 200 mA (10-19.1016.102)e- velocity cElectron framee-hνLaboratory frameBEAMLINE
Beamline 1-4: Materials Science ScatteringSi [1 1 1] R 0.9; Δλ/λ 2 e-4;mono α -7 D 2.7 mSampleMIRRORR 0.9SLITSDetectorOptical chamber: The “Coffin”Unfocused φ 4e11 hν s-1 mA-1Source size: 8 000 μm2Min q 0.015 nm-1Max d 400 nmSLITBent mirror, V focusBent, offcut Xtl mono,H focusSPEAR3 bend magnetI 500 mA, E 8333 eVσ(x), σ(y) 160 x 50 μm
Beamline 1-4 upstream optics: The ‘Coffin’Helium filleddrift tank:The ‘Coffin’Beamline 1-4(early design)Beamline 1-5X-rays
Inside the ‘Coffin’:Three jaw slitX-raysX-raysCu side shieldingCu Upper slitCu Side slitCu Lower slit
Inside the ‘Coffin’: Cu cooled Bent Mirror M0Finger comb pressingcontact onto M0Copper contact barBending rodsCu terminus blockX-raysM0 SiO2 blockCu braid, welded to bar
M0 coolingCu terminusHelium exit forMono coolingInside the ‘Coffin’:He Cooled Si MonoSi [111]crystal1-4 monoassemblyM0 coolingCu braid
Monochromatorcooling assemblyHe Outletonto monoCu coilsaroundHe illed‘Coffin’
Beamline 1-4‘Coffin’Beamline 1-5X-raysBeamline 1-4stopper tankBeamline 1-4
Beamline 1-4 Tankstopper 2stopper 1Inside 1-4 stopper tankMonocrystalEach stopper1.25” Cu 2 x3/16” Pb
SSRL Beamline 1-4: SAXS Materials ScienceN2 supplyionchambersshuttersamplestageCCD detectorguardslitsoptical rail & tableX-raysbeamdefiningslits
Experimental HutchIon chamber readoutMotor position encodersHutch stopper controlElectronics control chassisMotor control chassisBeamline control computerSample temperaturecontrol
Sample Environments: GoniometerUsed for Reflection X-ray geometriesHuber 410 GoniometerTwo axesangular translationTwo axeslinear translation
Sample Environments: X-Y drivable flat mountFour sample positionsx and y drives 2.25µmx and y throw 100mmAdaptor to hold fluid cellsFluid cell with flow feeds
Sample Environments: OvenTemp T: 25 C T 450 Cstability 2 CFit for fluidFeed for inert gasholdercells10 soldering ironcore heaters
Sample Environments: OvenFluid holder cells: assemble as three parts with windowsSample volume 2.5 ccOptical path length 1 mmMaterial: 5 each ofPolytetrafluoroethylene (Teflon); Aluminum & SteelTeflon cellshave flowcouplingsfor in-situtitration
Sample Environments: TensiometerDrive motorExtension rate E:0.001 mm s-1 E 25 mm s-1Oven Temp T: 25 C T 100 C OvenTemp stability 2 CExternalInternal heater tapesheater tapeElastomericPolypropylenesample at300% extension
Principal Parameters for Scattering Experimentsqmin: 0.03 nm-1 (c.f. pre 2004 qmin 0.07 nm-1)Can observe features dmax 200 nm (c.f. pre-2004 dmax 90 nm)Focused Flux Φ 1 x 1010 hν s-1 mA-1pre 2004 source sizeCurrent source sizeSource size 18 nm/rad(c.f. pre 2004 130 nm/rad)Sample to detector distanceD 3 m (c.f. pre 2004 D 1.2m)
John A Pople Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Center, Stanford CA 94309 Everything You Ever Wanted to Know About S A X S But Were Afraid to Ask. When should I use the Scattering Tec
W. Wiyatno, J. A. Pople, A.P. Gast, R.M. Waymouth, G.G. Fuller Under tensile stretching, high-tacticity fractions contribute to the equatorial and off-axis diagonal scatterings, revealing molecular-scale orientation parallel to the strain axis and crystalline phase
Answers Small-Angle X-Ray Scattering 14 The SAXS Technique SAXS Data from a Protein Complex . Modern improvements of this technique include . complex fluids, biology and materials science. It has been ever-growing since its inception some 35 years ago. The
Big Protein Small Protein Intensity Mica Windows. (small SAXS signal) Sample Requirements: 15 μL volume of 1-15 mg ml-1 protein. Protein solution must be homogeneous (monodisperse). Buffer solution—electron density should not exceed protein electron density. Degrees SAXS Data Collection
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