ppt-小角光散射(SLS)精要.pdfVIP

INTRODUCTION TO SMALL-ANGLE SCATTERING Elliot Gilbert Project Leader, SANS Instrument Replacement Research Reactor Outline What size range ? From atomic scattering to particle (assembly of atoms) scattering How is experiment performed and what is measured ? Scattering from dilute particles Form Factors Model independent analysis (NB - not obtain structure directly) Guinier’s Law; Porod’s Law; P(r) function Scattering from non-dilute systems Model dependent analysis Crystallography Microstructure Structure Viruses Proteins Bacteria Micelles Polymers Atomic Structures Porous Media Precipitates Grain Structures TEM USANS DIFFRACTION SANS/SAXS X-ray, n, e 10-1000 ? Optical microscopy DLS Light scattering 10-11 m10-9 10-7 10-5 10-3 Biology and Medicine: Proteins (folding, degradation) Complexes (incl. DNA) Amyloid plaque (Alzheimer’s) /education/feature/TMV/Images/ Polymer Physics, Materials Science and Engineering: Self-assembly and templating Physics, Geology, Metallurgy: Emulsions and Microemulsions Phase separation mechanisms Ferrofluids Demixing Kinetics Drug encapsulation Fractal Growth Materials under shear Bragg’s Law λ = 2d sinθ Scattering Vector, q kf = 2π/λ q/2 = ki,f sinθ θ q -ki Bragg’s Law λ = 2d sinθ q = kf - ki = (4π/λ)sinθ INVERSE DISTANCE Small angle = ‘large’ distance λ = 2d sinθ q = kf - ki = (4π/λ)sinθ sinθ = qλ/4π = λ/2d → d = 2π/q Small angle → sma