Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session J46: Focus Session: X-ray and Neutron Instruments and Measurement Science |
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Sponsoring Units: GIMS Chair: Albert Migliori, Los Alamos National Laboratory Room: Hilton Baltimore Holiday Ballroom 5 |
Tuesday, March 19, 2013 2:30PM - 3:06PM |
J46.00001: Coherent Imaging Invited Speaker: Stefano Marchesini |
Tuesday, March 19, 2013 3:06PM - 3:18PM |
J46.00002: Coherent Diffraction Imaging of Device Nanostructures Edwin Fohtung, Jong Woo, Martin Holt, Stephan Hruszkewycz, Na Lei, Dafine Ravelosona, Ross Harder, Eric Fullerton, Ian McNulty, Oleg Shpyrko We employ x-ray coherent diffraction imaging to map the lattice strain distribution, elastic properties and device responses to external stimuli such as magnetic and electric field in a host of device nanostructures. For the case isolated Ni (001) nanowire grown vertically on an amorphous SiO2 /Si substrate we utilize the retrieved projection of lattice distortion to predict the Young's Modulus of the wire based on the elasticity theory [1]. We also image for the first time, the evolution of magnetostriction in these wires in the presence of an external magnetic field. For extended ferroelectric thin films, we utilized the recently developed Bragg Ptychography [2] to image the evolution of ferroelectricity [3].\\[4pt] [1] E. Fohtung et al., Appl. Phys. Lett. 101, 033107 (2012).\\[0pt] [2] S. O. Hruszkewycz et al., Nano Lett. 12, 5148 (2012).\\[0pt] [3] E. Fohtung et al., in preparation (2012). [Preview Abstract] |
Tuesday, March 19, 2013 3:18PM - 3:30PM |
J46.00003: Development of a 10 nm spatial resolution Hard X-ray Microscope for the Nanoprobe beamline at NSLS-II Evgeny Nazaretski, Hanfei Yan, Jungdae Kim, Kenneth Lauer, Kazimierz Gofron, Deming Shu, Yong Chu We present recent progress on the development of an x-ray microscope for the Hard X-ray Nanoprobe (HXN) beamline at NSLS-II. We discuss design approach suitable for achieving sub-10 nm spatial resolution x-ray fluorescence and diffraction measurements. Different types of focusing optics e.g. Multilayer Laue Lenses (MLL) and Zone Plates (ZP) will be implemented in the microscope yielding diverse scientific applications for the targeted spatial resolutions of 10 nm and 30 nm respectively. We discuss modular design of the microscope that enables multi-functionality and includes the possibility to regulate temperature at the sample location. The design of the microscope is greatly based on our in-depth evaluation of numerous commercially available components; detailed studies of their performance in terms of mechanical stability, resolution, and thermal characteristics. Also, our design approach greatly relies on extensive experience acquired during construction and subsequent using of a prototype scanning MLL-based microscope. [Preview Abstract] |
Tuesday, March 19, 2013 3:30PM - 3:42PM |
J46.00004: Application of ultra-small-angle X-ray scattering / X-ray photon correlation spectroscopy to relate equilibrium or non-equilibrium dynamics to microstructure Andrew Allen, Fan Zhang, Lyle Levine, Jan Ilavsky Ultra-small-angle X-ray scattering (USAXS) can probe microstructures over the nanometer-to-micrometer scale range. Through use of a small instrument entrance slit, X-ray photon correlation spectroscopy (XPCS) exploits the partial coherence of an X-ray synchrotron undulator beam to provide unprecedented sensitivity to the dynamics of microstructural change. In USAXS/XPCS studies, the dynamics of local structures in a scale range of 100 nm to 1000 nm can be related to an overall hierarchical microstructure extending from 1 nm to more than 1000 nm. Using a point-detection scintillator mode, the equilibrium dynamics at ambient temperature of small particles (which move more slowly than nanoparticles) in aqueous suspension have been quantified directly for the first time. Using a USAXS-XPCS scanning mode for non-equilibrium dynamics incipient processes within dental composites have been elucidated, prior to effects becoming detectable using any other technique. [Preview Abstract] |
Tuesday, March 19, 2013 3:42PM - 3:54PM |
J46.00005: Solution measurements yield atomic scale resolution Derek Mendez, Jongmin Sung, Daniel Ratner, Clement Levard, Marc Michel, Gordon Brown, Sebastian Doniach A conventional measure on a solution of identical non-interacting particles (e.g. a dilute solution of proteins) is the scattering averaged over all particle orientations. Such scattering results in a 1-D profile, e.g. the standard powder diffraction rings. Here, we aim to recover information that is averaged out in such a measurement. By recording many short, bright X-ray pulses one can obtain the scattering fluctuation, i.e. the 2-photon correlation function. Intensity correlations arise from double scattering events in which two photons from an incoming beam scatter off the same particle, belonging to an ensemble of randomly oriented particles. The double scattering must occur during a single exposure, and before the scatterer has undergone significant diffusion. At wide angles, such correlations have the potential to yield {\AA}-scale single-particle structural information. The problem is to extract correlated events from a background of uncorrelated single-photon scattering events. This is done by forming statistics over an ensemble of correlation measurements and comparing to correlations between uncorrelated pairs of exposures. Samples range from naturally occurring nano-minerals measured using focused synchrotron X-rays, to biomolecules measured using a free electron laser. [Preview Abstract] |
Tuesday, March 19, 2013 3:54PM - 4:06PM |
J46.00006: Interpreting SAXS spectra of non-spherical nonane-water nanodroplets using a new particle form factor Abdalla Obeidat, Fawaz Hrahsheh, Gerald Wilemski, Harshad Pathak, Barbara Wyslouzil The structure of nanodroplets plays a critical role in many natural phenomena involving atmospheric nucleation and aerosol formation. Here, we review our theoretical efforts to interpret experimental measurements of small angle x-ray scattering (SAXS) from nonane/water nanodroplets formed in supersonic nozzles. We simulated nonane/water nanodroplets using classical molecular dynamics (MD) and found that they have a nonspherical Russian-Doll (RD) structure consisting of a roughly spherical water droplet partially wetted by a large nonane lens. We have developed an exact analytical expression for the particle form factor P(q) of a lens-on-sphere droplet with sharp interfaces and uniform lens and sphere densities for use in fitting the experimental data. The model was validated by comparing it with exact results for P(q) based on the MD simulations. Excellent agreement was found. The fits of the measured SAXS spectra generated with this model are good and generally better than those based on simpler structural models, but the resulting particle size distributions do not produce mass balance for either water or nonane. Further work is needed to resolve this discrepancy. [Preview Abstract] |
Tuesday, March 19, 2013 4:06PM - 4:18PM |
J46.00007: Radiation Induced Defect Clusters in Fe and Fe-alloys Investigated by X-Ray Diffuse Scattering Measurements and Molecular Dynamics and Monte Carlo Simulations Ben Larson, Jon Tischler, Hongbin Bei, Roger Stoller, Haixuan Xu, Yanwen Zhang We have initiated fundamental investigations of 15 MeV Ni-ion induced defect clusters in single crystal Fe and Fe-Cr using diffuse scattering measurements near Bragg reflections combined with molecular dynamics (MD) and self-evolving atomistic kinetic Monte Carlo (SEAK-MC) simulations. Synchrotron x-ray diffuse scattering measurements performed near the (002) reflection of \textless 001\textgreater oriented Fe and Fe(30{\%})Cr single crystals are analyzed within the so-called asymptotic regime using scattering cross-sections based on MD simulated local lattice distortions and SEAK-MC generated interstitial and vacancy cluster configurations. Measurements for Ni-ion irradiations of Fe and Fe-Ni with doses corresponding to 0.2 and 1 displacements per atom (DPA) at ambient temperature will be presented and discussed in connection with the local Bragg scattering interpretation of defect cluster diffuse scattering in ion-irradiated Cu. Methods for calculating diffuse scattering cross sections directly from MD simulations of atomic displacements around vacancy and interstitial loops within the single defect approximation will be considered and the importance of such approaches for complex defect clusters will be addressed. [Preview Abstract] |
Tuesday, March 19, 2013 4:18PM - 4:30PM |
J46.00008: Investigation of the experimental effects on the quality of the rapid acquisition pair distribution function (RA-PDF) data Ahmad S. Masadeh Series of experiments have been carried out to investigate the quality of the recently developed rapid acquisition atomic pair distribution function (RA-PDF) method, which combines the uses of high energy X-rays and an image plate area detector. Image plate data for simple elements (C, Mg, Al, Si, Ni, Cu, Zn, Ag, and Pb) have been analyzed, using (RA-PDF) technique. The affect of undiscriminated Compton and fluorescence is investigated for a wide range of materials with atomic Z numbers ranging from 6(Carbon) and 82 (Pb). We find the RA-PDF method is capable of obtaining high quality PDFs where quantitatively reliable structure information can be extracted. [Preview Abstract] |
Tuesday, March 19, 2013 4:30PM - 4:42PM |
J46.00009: Test of the Cross Correlation Method for Efficient Single Crystal Diffuse Neutron Scattering with Elastic Discrimination Stephan Rosenkranz, John Paul Castellan, Rich Vitt, Raymond Osborn, Rick Riedel, Mariano Ruiz-Rodriguez, Loren Funk Single crystal diffuse scattering provides a powerful probe of the complex disorder associated with many emergent phenomena of great interest. It provides a determination not only of the local distortions around a point defect but also of the length scale and morphology of short-range order on the nanoscale. However, obtaining accurate models of the local structure usually demands measurements over large volumes of reciprocal space with sufficiently high momentum and energy resolution. In order to overcome limitations of current instrumentation, we propose to utilize the cross-correlation method at pulsed neutron sources. This concept that combines the high efficiency of white-beam Laue diffraction for measuring large volumes of reciprocal space with energy discrimination produced by the use of a statistical chopper is currently being implemented in a dedicated instrument, { \it Corelli }, under construction at the Spallation Neutron Source. Here, we present our detailed investigation of the effectiveness of this method for measuring weak diffuse signals, based on full experiment simulations as well as actual measurements of the diffuse scattering from powder and single crystal samples obtained utilizing the cross correlation method on a prototype instrument. [Preview Abstract] |
Tuesday, March 19, 2013 4:42PM - 4:54PM |
J46.00010: Design of Ultra Small Angle Neutron Scattering (KIST-USANS) at HANARO Cold Neutron Guide, CG4B Man-Ho Kim The ultra small angle neutron scattering instrument can measure the lower limit of scattering vector to near Q $\sim$ 2.0x10$^{-5}$ {\AA}$^{-1}$ while the upper limit can reach to an intermediate scattering vector Q $\sim$ 10$^{-2}$ {\AA}$^{-1}$ of a typical small angle neutron scattering (SANS) depending on the contrast of sample. USANS is useful when measuring objects that are micron to submicron in size while SANS is useful when measuring objects that are micron to nano in size. When both USANS and SANS were used together, we could measure sizes from micron to nano scale, which is useful when studying the hierarchical structures in the wide scale of Q and total cross-section, d$\Sigma $/d$\Omega $(Q). Recently, KIST has developed the USANS (so called KIST-USANS) at HANARO cold neutron guide hall of KAERI. We will present the instrument design, performance, future plan, and some examples of measurements that cover approximately 11 orders of magnitude in the d$\Sigma $/d$\Omega $(Q) and 4 orders in the Q. [Preview Abstract] |
Tuesday, March 19, 2013 4:54PM - 5:06PM |
J46.00011: Photon Source Capabilities of the Jefferson Lab THz to VUV FEL G.P. Williams, S.V. Benson, D. Douglas, P. Evtushenko, F.E. Hannon, C. Hernandez-Garcia, J.M. Klopf, R.A. Legg, G.R. Neil, M.D. Shinn, C.D. Tennant, S. Zhang Jefferson Lab operates a sub-picosecond photon science R\&D facility with peak and average brightness values that are many orders of magnitude higher than storage rings in the THz - VUV range. It also has multiphoton capabilities that provide unique opportunities for out of equilibrium dynamical studies at time-scales down to $\sim$ 100 fs FWHM. The facility is based on a superconducting energy recovered linac which is operated with CW RF that powers oscillator-based IR and UV Free Electron Lasers (FELs) with diffraction limited sub-picosecond pulses with $>$ 10$^{13}$ photons per pulse (1.0\% BW) at pulse repetition frequencies up to 75 MHz. Details of the facility and its present performance will be presented along with some example science applications. In addition we will discuss on-going upgrades to the facility that will allow 10 eV lasing in the fundamental. Finally we will present two potential upgrades including the design of an oscillator-based VUV-FEL that would produce 6 $\times$ 10$^{12}$ coherent (0.5\% BW) 100 eV photons per pulse at multi-MHz repetition rates in the fundamental, and a dual FEL configuration that would allow simultaneous lasing at THz and UV wavelengths. [Preview Abstract] |
Tuesday, March 19, 2013 5:06PM - 5:18PM |
J46.00012: Picosecond Time-Resolved Strain Rosette at Atomic Length Scale Maria I. Campana, G. Jackson Williams, Soo Heyong Lee, Donald Walko, Eric Landahl Ultrafast optical absorption in a crystalline solid generates coherent motions of strain, which propagate through the bulk at the speed of sound. Energy relaxation dynamics of the excited lattice system and the subsequent transport properties of the strains have been actively studied. Recently, these high-speed transient dynamics have been studied using laser based pump-probe techniques and time resolved x-ray diffraction (TRXD). However, the interpretation of these studies always assumes a uniaxial spatial profile for the strain (i.e. strain is exerted only along the direction of surface normal of the sample). This assumption comes from a symmetry argument originally given by Thomsen: if the illuminated area of the pump laser beam on the sample surface is much larger than the optical penetration depth, strain gradient along surface normal is expected to be much steeper than along lateral direction, and therefore, the strain generated is usually assumed to be one dimensional. While this assumption simplifies the analysis of the data, (and makes possible such applications as picosecond ultrasonics for the in-situ measurement of semiconductor heterostructure thickness), it overlooks any physical processes that take place along transverse direction. Here we report the experimental generation and detection of the transverse component of the impulsively generated strain in a single GaAs crystal using TRXD. Our analysis is based on a strain rosette applied to three non-collinear Bragg reflections. [Preview Abstract] |
Tuesday, March 19, 2013 5:18PM - 5:30PM |
J46.00013: A high-energy x-ray precession camera at the Advanced Photon Source A. Kreyssig, D.K. Pratt, M. Ramazanoglu, G. Tucker, D.S. Robinson, L.C. Lang, R.J. McQueeney, A.I. Goldman A key distinguishing feature of the APS is the capability for high-energy x-ray scattering, which has been exploited for numerous powder sample applications. The instrumentation for high-energy single-crystal diffraction measurements at the APS, however, remains underdeveloped. High-energy x-rays offer several advantages: (1) absorption effects are minimized and the entire bulk of the sample is probed and; (2) a large range of reciprocal space can be imaged when used together with even a modestly sized area detector. We have developed a high-energy x-ray precession camera (HEXPC) for imaging of reciprocal-space planes. This technique is highly suited to studies of Bragg and diffuse scattering with its flexibility in dynamic range, resolution and scattering vector range. These capabilities have been demonstrated by studies of single crystals and quasicrystals. \\[4pt] The work at the Ames Laboratory was supported by US DOE, Office of Basic Energy Sciences, DMSE, contract DE-AC02-07CH11358. [Preview Abstract] |
Tuesday, March 19, 2013 5:30PM - 5:42PM |
J46.00014: SESAME as a Model Project for Other Regions Herman Winick UNESCO became the umbrella organization for SESAME at its Executive Board 164th session, May 2002. The following comments about SESAME were made by this board: ``a quintessential UNESCO project combining capacity building with vital peace-building through science'' and ``a model project for other regions.'' Now that SESAME is well underway, other regions (e.g.; Africa and Central Asia) should be made aware of this progress, and they should be welcomed to join SESAME as a first step in developing similar projects in their region. Students and scientists from other regions should be encouraged to attend SESAME Users' meeting, schools, workshops, etc. where they can learn about synchrotron radiation sources, beamlines, and science. They should be invited to join SESAME scientists in designing and commissioning accelerators and beamlines, gaining relevant experience for their own projects and helping SESAME in the process. [Preview Abstract] |
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