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ABSTRACT: As an increasingly important structural-characterization technique, grazing-incidence X-ray scattering (GIXS) has found wide applications for in situ and real-time studies of nanostructures and nanocomposites at surfaces and interfaces. A dedicated beamline has been designed, constructed and optimized at beamline 8-ID-E at the Advanced Photon Source for high-resolution and coherent GIXS experiments. The effectiveness and applicability of the beamline and the scattering techniques have been demonstrated by a host of experiments including reflectivity, grazing-incidence static and kinetic scattering, and coherent surface X-ray photon correlation spectroscopy. The applicable systems that can be studied at 8-ID-E include liquid surfaces and nanostructured thin films.
Journal of Synchrotron Radiation 07/2012; 19(Pt 4):627-36. · 2.73 Impact Factor
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Carlee E Ashley,
Darren R Dunphy,
Zhang Jiang,
Eric C Carnes,
Zhen Yuan,
Dimiter N Petsev,
Plamen B Atanassov,
Orlin D Velev, Michael Sprung,
Jin Wang,
David S Peabody,
C Jeffrey Brinker
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ABSTRACT: The rapid assembly of icosohedral virus-like particles (VLPs) into highly ordered (domain size > 600 nm), oriented 2D superlattices directly onto a solid substrate using convective coating is demonstrated. In-situ grazing-incidence small-angle X-ray scattering (GISAXS) is used to follow the self-assembly process in real time to characterize the mechanism of superlattice formation, with the ultimate goal of tailoring film deposition conditions to optimize long-range order. From water, GISAXS data are consistent with a transport-limited assembly process where convective flow directs assembly of VLPs into a lattice oriented with respect to the water drying line. Addition of a nonvolatile solvent (glycerol) modified this assembly pathway, resulting in non-oriented superlattices with improved long-range order. Modification of electrostatic conditions (solution ionic strength, substrate charge) also alters assembly behavior; however, a comparison of in-situ assembly data between VLPs derived from the bacteriophages MS2 and Qβ show that this assembly process is not fully described by a simple Derjaguin-Landau-Verwey-Overbeek model alone.
Small 03/2011; 7(8):1043-50. · 8.35 Impact Factor
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ABSTRACT: A method is developed for calculating the small-angle x-ray scattering originating from within the interior of a thin film under grazing incidence illumination. This offers the possibility of using x-ray scattering to probe how the structure of polymers is modified by confinement. When the diffuse scattering from a thin film is measured over a range of incident angles, it is possible to separate the contributions to scattering from the interfaces and the contribution from the film interior. Using the distorted-wave Born approximation the structure factor, S(q), of the film interior can then be obtained. We apply this method to analyze density fluctuations from within the interior of a silicon supported molten polystyrene (PS) film. Measurements were made as a function of film thickness ranging from one to ten times the polymer radius of gyration (Rg). The compressibility, calculated by extrapolating the measured S(q) to q=0, agrees well with that of bulk PS for thick films, but thinner films exhibit a peak in S(q) near q=0. This peak, which grows with decreasing thickness, is attributed to a decreased interpenetration of chains and a consequent enhanced compressibility.
Physical Review E 07/2010; 82(1 Pt 1):011804. · 2.26 Impact Factor
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ABSTRACT: We have observed a sharp slowing down of the relaxation of the liquid meniscus for poly(n-alkyl acrylate) at temperatures where there are no abrupt changes in bulk viscosity or surface tension. This slowing down is due to the formation of a surface-ordered monolayer above the bulk melting temperatures. X-ray photon correlation spectroscopy measurements reveal that the surface capillary fluctuations are also significantly slower due to the formation of the ordered monolayer for film thicknesses comparable to that of the precursor films. The slowing down of the precursor film dynamics is responsible for slower meniscus relaxation below the surface ordering transition temperature.
Physical Review Letters 04/2010; 104(13):137801. · 7.37 Impact Factor
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ABSTRACT: Critical photonic, electronic, and magnetic applications of two-dimensional nanocrystal superlattices often require nanostructures in perfect single-crystal phases with long-range order and limited defects. Here we discovered a crystalline phase with quasi-long-range positional order for two-dimensional nanocrystal superlattice domains self-assembled at the liquid-air interface during droplet evaporation, using in situ time-resolved X-ray scattering along with rigorous theories on two dimensional crystal structures. Surprisingly, it was observed that drying these superlattice domains preserved only an orientational order but not a long-range positional order, also supported by quantitative analysis of transmission electron microscopy images.
Nano Letters 03/2010; 10(3):799-803. · 13.20 Impact Factor
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ABSTRACT: The thermal stability of highly ordered two-dimensional superlattices consisting of dodecanethiol-ligated Au nanoparticles has been investigated using in situ grazing incidence small-angle x-ray scattering in air and in vacuum. In the lower temperature region (<70 °C), annealing in air results in a minimal change of superlattice structure, whereas annealing in vacuum leads to a considerable lattice contraction and a decrease in long-range order. At higher temperatures (>100 °C), ligand desorption causes nanocrystals to sinter locally, destroying quasi-long-range order. The sintering process is significantly enhanced in vacuum compared to the case in air due to the increased desorption rate of thiol ligands under low pressure.
Journal of Physics Condensed Matter 07/2009; 21(26):264011. · 2.55 Impact Factor
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Darren R Dunphy,
Todd M Alam,
Michael P Tate,
Hugh W Hillhouse,
Bernd Smarsly,
Andrew D Collord,
Eric Carnes,
Helen K Baca,
Ralf Köhn, Michael Sprung,
Jin Wang,
C Jeffrey Brinker
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ABSTRACT: The nanostructure of silica and hybrid thin film mesophases templated by phospholipids via an evaporation-induced self-assembly (EISA) process was investigated by grazing-incidence small-angle X-ray scattering (GISAXS). Diacyl phosphatidylcholines with two tails of 6 or 8 carbons were found to template 2D hexagonal mesophases, with the removal of lipid from these lipid/silica films by thermal or UV/O3 processing resulting in a complete collapse of the pore volume. Monoacyl phosphatidylcholines with single tails of 10-14 carbons formed 3D micellular mesophases; the lipid was found to be extractable from these 3D materials, yielding a porous material. In contrast to pure lipid/silica thin film mesophases, films formed from the hybrid bridged silsesquioxane precursor bis(triethoxysilyl)ethane exhibited greater stability toward (both diacyl and monoacyl) lipid removal. Ellipsometric, FTIR, and NMR studies show that the presence of phospholipid suppresses siloxane network formation, while actually promoting condensation reactions in the hybrid material. 1D X-ray scattering and FTIR data were found to be consistent with strong interactions between lipid headgroups and the silica framework.
Langmuir 07/2009; 25(16):9500-9. · 4.19 Impact Factor
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ABSTRACT: The design and performance of a novel ultra-high-vacuum-compatible artificial channel-cut monochromator that has been commissioned at undulator beamline 8-ID-I at the Advanced Photon Source are presented. Details of the mechanical and optical design, control system implementation and performance of the new device are given. The monochromator was designed to meet the challenging stability and optical requirements of the X-ray photon correlation spectroscopy program hosted at this beamline. In particular, the device incorporates a novel in-vacuum sine-bar drive mechanism for the combined pitch motion of the two crystals and a flexure-based high-stiffness weak-link mechanism for fine-tuning the pitch and roll of the second crystal relative to the first crystal. The monochromator delivers an exceptionally uniform and stable beam and thereby improved brilliance preservation.
Journal of Synchrotron Radiation 02/2008; 15(Pt 1):12-8. · 2.73 Impact Factor
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ABSTRACT: As an increasingly important structural‐characterization technique, grazing‐incidence small‐angle scattering (GISAXS) finds vast applications in nanostructures and nanocomposites at surfaces and interfaces for in situ and real‐time studies because of its probing q‐range (10−3 – 1 nm−1) and temporal resolution (10−3 – 1 s). At the Advanced Photon Source (APS), GISAXS techniques under thin‐film waveguide‐based resonance conditions were developed to study the diffusion phenomena in nanoparticle/polymer nanocomposites. Also, the kinematics of nanoparticle crystal formation at air/liquid interfaces has been obtained by the similar method in real time during the liquid droplet evaporation. To meet the strong demand from the nanoscience community, a dedicated GISAXS beamline has been designed and constructed as a part of the 8‐ID‐E beamline at the APS. This dedicated GISAXS setup was developed based on a 4‐circle diffractometer so that precise reflectivity of the sample can be measured to complement the GISAXS analysis under the dynamical refection conditions. © 2007 American Institute of Physics
AIP Conference Proceedings. 01/2007; 879(1):1387-1390.
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ABSTRACT: Multispeckle x-ray photon correlation spectroscopy measurements, carried out at beamline 8-ID at the Advanced Photon Source at Argonne National Laboratory, of opaque suspensions of silica nanoparticles in water and lutidine-water binary mixtures are presented.
MRS Proceedings. 12/2006; 1027.
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ABSTRACT: We present design and characterization results of a novel ultra-high-vacuum-compatible artificial channel-cut monochromator that has been installed at the undulator beamline 8-ID-I at the Advanced Photon Source. The monochromator has been designed to meet the challenging stability and optical requirements of the x-ray photon correlation spectroscopy program hosted at this beamline. In particular, the device incorporates a novel in-vacuum sinebar drive mechanism for the combined pitch motion of the two crystals and a flexure-based high-stiffness weak-link mechanism for fine tuning the pitch and roll of the second crystal relative to the first crystal.
Advances in X-Ray/EUV Optics, Components, and Applications, San Diego, CA, United States; 01/2006
