Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session Z24: Neutron, Light, and X-ray Optics and Sources |
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Sponsoring Units: GIMS Chair: Ao Teng, University of Tennessee Room: 504 |
Friday, March 7, 2014 11:15AM - 11:27AM |
Z24.00001: Synchrotron X-ray Optics Testing at Beamline 1-BM at the Advanced Photon Source Albert Macrander, Naresh Kujala Beamline 1-BM at the Advanced Photon Source has been reconfigured, in part for testing of synchrotron optics with both monochromatic and white beams. Monochromatic energies between 6 and 30 keV are available. Primary agendas include both white beam and monochromatic beam topography, Talbot grating interferometry for measurement of coherence lengths and wavefronts, and micro-focusing. Recent examples will include topography of sapphire , tests of Kirkpatrick-Baez mirrors, and tests of multilayer Laue lenses. Analyzers for Inelastic X-ray Scattering has also been characterized by two user groups. [Preview Abstract] |
Friday, March 7, 2014 11:27AM - 11:39AM |
Z24.00002: A diffractive-optic based nonlinear optical generation spectrometer for measurement of crystallographic and magnetic point group symmetries David Hsieh, Darius Torchinsky Nonlinear optical generation from a crystalline material can provide information about both its crystallographic and magnetic point group symmetries and may therefore be exploited as a complementary technique to diffraction based scattering probes. However, this is challenging to put into practice because the experiment should ideally be sensitive to all elements of the nonlinear optical susceptibility tensor. This involves being able to measure the intensity of nonlinear optical generation either transmitted or reflected from a crystal as a function of oblique light incidence direction, polarization and frequency. These requirements are even more difficult to achieve under extreme sample environments such as ultrahigh vacuum, low temperatures, high magnetic fields or high pressures. Here we present a novel experimental setup using a diffractive optic to realize such measurements. We demonstrate the efficacy of our scheme by showing results for low temperature lattice and magnetic symmetries of selected samples using optical second harmonic generation. [Preview Abstract] |
Friday, March 7, 2014 11:39AM - 11:51AM |
Z24.00003: Lensless imaging of atomic surface structures using ptychography in reflection mode Chenhui Zhu, Ross Harder, Ana Diaz, Vladir Komanicky, Andi Barbour, Ruqing Xu, Xiaojing Huang, Yaohua Liu, Michael Pierce, Hoydoo You We propose that atomic structures on single crystal surfaces can be imaged using a variation of coherent x-ray diffractive imaging. This is a lensless ptychographic technique applied along the crystal truncation rod in reciprocal space. Simulations show that the highest sensitivity on the monolayer surface structure is obtained at the anti-Bragg condition. We demonstrate the feasibility of ptychographic reconstruction from experimental data collected in reflection mode by reconstruction of atomic steps on a crystal surface. This work and use of the Advanced Photon Source and the Electron Microscopy Center for Materials Research were supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The work at Safarik University is supported by Slovak grant VEGA 1/0782/12 and ERDF EU grant under contract No. ITMS 26220120005 [Preview Abstract] |
Friday, March 7, 2014 11:51AM - 12:03PM |
Z24.00004: Hanbury Brown and Twiss interferometry at a free-electron laser Andrej Singer Measurements of second- and higher-order intensity correlation functions (so-called Hanbury Brown-Twiss experiment) performed at the free-electron laser (FEL) FLASH in the non-linear regime of its operation are presented. We demonstrate the high transverse coherence properties of the FEL beam with a degree of transverse coherence of about 80{\%} in the vertical direction and a degeneracy parameter on the order of 10$^{\mathrm{9}}$. Intensity correlation measurements in spatial and frequency domain yield an estimate of the FEL average pulse duration of 50 fs. These characteristics make the FEL similar to optical laser sources. Our measurements of the higher-order correlation functions indicate that FEL radiation obeys Gaussian statistics, which is characteristic to chaotic sources. A. Singer, U. Lorenz, F. Sorgenfrei, N. Gerasimova, J. Gulden, O. M. Yefanov, R. P. Kurta, A. Shabalin, R. Dronyak, R. Treusch, V. Kocharyan, E. Weckert, W. Wurth, and I. A. Vartanyants. Phys. Rev. Lett. \textbf{111}, 034802 (2013) [Preview Abstract] |
Friday, March 7, 2014 12:03PM - 12:15PM |
Z24.00005: An ultra-high energy resolution and wide energy range soft X-ray beamline in SSRF Y.-B. Shi, R. Ruben, L. Xue, Y. Zou, Y. Wang, R.-Z. Tai, H. Ding A new ultra-high energy resolution and wide energy range soft X-ray beamline is designed and is being constructed in Shanghai Synchrotron Radiation Facility (SSRF), which has two experimental stations: angle resolved photoemission spectroscopy (ARPES) and photoelectron emission microscopy (PEEM). The source is a pair of EPUs covering the evergy ranges 20 to 200 eV and 200 to 2000 eV with arbitrary polarized light. The beamline, based on a plane grating monochromator(PGM) and four variable line spacing gratings, will deliver flux higher than 1.0$\times10^{12}$ photons/s/0.01\%BW. A grating dedicated for high energies and very high resolution will provide more than 5$\times10^{10}$ photons/s at 1 keV with a resolution of 14 meV. The refocusing for both endstations is based on KB pairs with which the spot size will be 15$\times4.7 \mu m^{2}$ (hor.$\times$ver. FWHM) at ARPES and 9.9$\times4.8 \mu m^{2}$ (hor.$\times$ver. FWHM) at PEEM, respectively, with a 10 $\mu m$ exit slit. Owing to high thermal radiation from the source, a new method is used to eliminate the influence of the thermal deformation on mirrors in order to achieve ultra-high energy resolution. [Preview Abstract] |
Friday, March 7, 2014 12:15PM - 12:27PM |
Z24.00006: kHz tabletop coherent soft X-ray source enabled by single-stage 10 mJ Ti:sapphire amplifier Chengyuan Ding, Wei Xiong, Tingting Fan, Daniel Hickstein, Henry Kapteyn, Margaret Murnane We present a tabletop source of bright, broadband, soft X-rays with photon energies up to 300 eV. By driving the harmonic generation process using 1.3 $\mu $m light in a high-pressure, phase matched geometry, we significantly enhance the soft X-ray flux and stability. We achieve a photon flux \textgreater 10$^{8}$~photons/s/1{\%} bandwidth, which emerges as a soft x-ray supercontinuum. Utilizing this broad bandwidth, we can implement high-quality x-ray absorption spectroscopy of multiple elements and transitions in a single spectrum. Near edge fine structure is obtained from molecular samples (CS$_{2}$ and SF$_{6})$. Furthermore, we demonstrate the applicability of this source to transient absorption studies by measuring the transient soft X-ray absorption of xenon plasma with high spectral sensitivity and femtosecond temporal resolution. [Preview Abstract] |
Friday, March 7, 2014 12:27PM - 12:39PM |
Z24.00007: High average power, high repetition rate table-top soft x-ray lasers for applications in nanoscience and nanotechnology Brendan Reagan, Keith Wernsing, Cory Baumgarten, Leon Durivage, Mark Berrill, Alden Curtis, Federico Furch, Brad Luther, Mark Woolston, Dinesh Patel, Carmen Menoni, Vyacheslav Shlyaptsev, Jorge Rocca There is great interest in table-top sources of bright coherent soft x-ray radiation for nanoscale applications. We report the demonstration of a compact, high repetition rate soft x-ray laser operating at wavelengths between 10.9nm to 18.9nm, including the generation of 0.15mW average power at $\lambda =$18.9nm and 0.1mW average power at $\lambda =$13.9nm. These short wavelength lasers were driven by an all diode pumped, chirped pulse amplification laser based on cryogenically-cooled Yb:YAG amplifiers that produces 1 Joule, picosecond duration pulses at 100 Hz repetition rate. Irradiation of solid targets results in the production of plasmas with large transient population inversions on the 4d$^{\mathrm{1}}$S$_{\mathrm{0}}\to $4p$^{\mathrm{1}}$P$_{\mathrm{1}}$ transition of Ni-like ions. Optimization of this high repetition rate laser combined with the development of high shot capacity, rotating targets has allowed the uninterrupted operation of this soft x-ray laser for hundreds of thousands of consecutive shots, making it suitable for a number of applications requiring high photon flux at short wavelengths. Work was supported by the NSF ERC for Extreme Ultraviolet Science and Technology using equipment developed under NSF Award MRI-ARRA 09-561, and by the AMOS program of the Office of Basic Energy Sciences, US Department of Energy. [Preview Abstract] |
Friday, March 7, 2014 12:39PM - 12:51PM |
Z24.00008: ABSTRACT WITHDRAWN |
Friday, March 7, 2014 12:51PM - 1:03PM |
Z24.00009: Determining Source Directionality from a Scattering Based Neutron Detector System Stephan Young, Cory Hoshor, James Currie, Tom Oakes, Joseph Crow, Paul Scott, William Miller, Anthony Caruso Three-dimensional directional resolve of neutrons over a wide energy range has proven to be a grand challenge. Various attempts to solve the problem, including neutron cameras and proton recoil based detectors have been met with limited success, with costs in efficiency as well as dimensional and field of view restrictions. To achieve true three dimensional directional resolution, empirical data and Monte Carlo N-Particle Transport Code (MCNP) modeling were used to explore response of a volumetrically sensitive scattering based system to a Cf source of varying angular orientation, then compared through three dimensional cross correlation analysis. [Preview Abstract] |
Friday, March 7, 2014 1:03PM - 1:15PM |
Z24.00010: ABSTRACT WITHDRAWN |
Friday, March 7, 2014 1:15PM - 1:27PM |
Z24.00011: Elimination of Optical Artifacts from Transmission FTIR Spectra for Quantitative Bond Density Analysis Milan Milosevic, Sean King Fourier transform infrared (FTIR) spectroscopy is a powerful technique for characterizing the chemical structure and the short range order in bulk solids and thin films. However, transmission FTIR spectra of thin films deposited on optically thick substrates are complicated by the presence of numerous ``optical effects'' that arise from reflections at the two surfaces and the interface of the film and substrate. The convolution of these ``optical effects'' with the true absorption spectrum of the film can cause quantitative analyses of FTIR spectra of the films on substrate to yield errors as large as 90{\%} in integrated absorbance and other quantitative parameters. In this report, we describe and demonstrate a method that enables such ``optical effects'' to be removed with complete rigor allowing the true absorption coefficient spectrum of the film to be obtained. Unlike prior methods that address the problem as a combination of coherent and incoherent reflections in the film and substrate respectively, we use the exact theoretical expression for the transmittance of a thin film on an optically thick substrate. We show that this allows us to naturally separate the undesired ``optical effects'' and desired thin film absorption spectrum into two separate terms. Using both simulated and experimental data we demonstrate that the term containing ``optical effects'' can be cleanly subtracted from the experimental FTIR spectra to yield the true absorption coefficient spectrum of the thin film allowing for rigorous quantitative bond density and, potentially, elemental composition of the films to be calculated from the thus corrected spectra. [Preview Abstract] |
Friday, March 7, 2014 1:27PM - 1:39PM |
Z24.00012: Low frequency all-optical thermoreflectance measurements of thin film thermal conductivities Kirby Myers, Hans D. Robinson We present an all-optical method for measuring the in-plane and cross-plane thermal conductivities in $\mu $m-thick films on substrates with dissimilar thermal conductivities. This method relies in thermooptically induced changes in reflectivity caused by a heating beam that is modulated with frequencies of up to 100 kHz. Because the method does not rely on ultrafast lasers, it is economical and can be incorporated in an experimental setup with a small footprint. Results from bulk samples and films with thermal conductivities ranging between about 1 Wm$^{\mathrm{-1}}$K$^{\mathrm{-1}}$and 100 Wm$^{\mathrm{-1}}$K$^{\mathrm{-1}}$will be presented. [Preview Abstract] |
Friday, March 7, 2014 1:39PM - 1:51PM |
Z24.00013: Bio-inspired Artificial Apposition Compound Eye Jianliang Xiao, Youngmin Song, Yizhu Xie, Viktor Malyarchuk, Yonggang Huang, John Rogers In arthropods, evolution has created a remarkably sophisticated class of imaging system, with wide angle field of view, low aberrations, high acuity to motion and infinite depth of field. A challenge in building digital cameras with the hemispherical, compound apposition layouts of arthropod eyes is that essential design requirements cannot be met with existing planar sensor technologies or conventional optics. We present ideas in materials, mechanics and integration schemes that enable scalable pathways to working, arthropod-inspired cameras in nearly full hemispherical shapes with surfaces densely populated by imaging elements (i.e. artificial ommatidia). The devices combine elastomeric compound optical elements with deformable arrays of thin silicon photodetectors, in co-integrated sheets that can be elastically transformed from the planar geometries in which they are fabricated, to hemispherical shapes for integration into apposition cameras. Experimental and theoretical studies reveal key aspects of the materials science and physics of these systems. Imaging results and quantitative ray-tracing based modeling illustrate essential features of their operation. [Preview Abstract] |
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