Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session Y24: Instrumentation and Measurements |
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Sponsoring Units: GIMS Chair: Ricardo Jimenez-Matinez, National Institute of Standards and Technology Room: 504 |
Friday, March 7, 2014 8:00AM - 8:12AM |
Y24.00001: Use of Atomic Layer Deposition to create homogeneous SRXF/STXM standards Nicholas Becker, Jeffrey Klug, Steve Sutton, Anna Butterworth, Andrew Westphal, John Zasadzinski, Thomas Proslier The use of Standard Reference Materials (SRM) from the National Institute of Standards and Technology (NIST) for quantitative analysis of chemical composition when analyzing samples using Synchrotron based X-Ray Florescence (SR-XRF) and Scanning Transmission X-Ray Microscopy (STXM) is common. However, these standards can suffer from inhomogeneity in chemical composition and often require further corrections to obtain quantitative results. This inhomogeneity can negatively effect the reproducibility of measurements as well as the quantitative measure itself, and the introduction of assumptions for calculations can further limit reliability. Atomic Layer Deposition (ALD) is a deposition technique known for producing uniform, conformal films of a wide range of compounds on nearly any substrate material. These traits make it an ideal deposition method for producing thin films to replace the NIST standards and create SRM on a wide range of relevant substrates. Utilizing Rutherford Backscattering, STXM, and SR-XRF we will present data proving ALD is capable of producing films that are homogenous over scales ranging from 100$\mu$m to 1nm on TEM windows. [Preview Abstract] |
Friday, March 7, 2014 8:12AM - 8:24AM |
Y24.00002: Experimental Platform for Studying Thermoelectric Properties in Vacuum Gaps and Molecular Junctions Wonho Jeong, Youngsang Kim, Kyeongtae Kim, Woochul Lee, Pramod Reddy Electromigrated break junction (EBJ) based molecular devices have enabled many research groups to study nanoscale charge transport. Although EBJ devices have been extensively used due to the advantages of a three terminal configuration in tuning the electronic structure, it has not been possible to use them to study thermoelectric properties. This is because creating temperature differentials across the nanogap of EBJs is technically challenging. In order to overcome this experimental limitation, we carefully designed and created a new experimental platform (EBJIH, EBJ with integrated heater) that enables us to study thermoelectric properties in vacuum gaps and molecular junctions. To prove that temperature differentials can be established in these three terminal devices, we performed nanometer resolution thermal imaging using scanning thermal microscopy under UHV conditions. The results clearly show that temperature differentials can indeed be established in the devices. Further, we have used these devices to study the thermoelectric properties of vacuum gaps between gold electrodes and found that the thermoelectric properties were very sensitive to gap dimensions. We are also currently adopting this platform to study thermoelectric properties in molecular junctions. [Preview Abstract] |
Friday, March 7, 2014 8:24AM - 8:36AM |
Y24.00003: Temperature Dependent Behavior of Near Field Radiative Heat Transfer Robert Joachim We have designed and implemented an apparatus capable of measuring near field radiative heat transfer (NFRT) from room temperature down to cryogenic temperatures in vacuum. Utilizing a bimaterial cantilever with a 20 $\mu $m glass sphere attached to the end in the pendulum geometry as a thermal detector and an optical fiber interferometer as a displacement detector we were able to measure the heat flux between a substrate and the glass sphere. The apparatus was sensitive enough to measure displacements of 1 nm and heat fluxes of 50 pW. NFRT was observed at temperatures ranging from 300K to 100K and at displacements down to 100nm. These measurements were performed for various combinations of Si, SiO$_{2}$ and sapphire. The thermodynamic formulation of Lifshitz's theory for attraction between dielectrics [1] predicts that NFRT will scale as T$^{2}$ while far field radiative transfer will scale as T$^{4}$ and that the crossover between these two regimes will occur at a distance given by (1/2$\pi )(\hbar $c/k$_{b}$T). Our data confirms these predictions. \\[4pt] [1] J. Loomis and H. Maris. Phys Rev. B. 50, 18517 (1994). [Preview Abstract] |
Friday, March 7, 2014 8:36AM - 8:48AM |
Y24.00004: Nanoscale volumetric chemical imaging by soft x-ray laser ablation mass spectrometry Ilya Kuznetsov, Jorge Filevich, Mark Woolston, Gerald Gasper, David Carlton, Weilun Chao, Erik Anderson, Elliot Bernstein, Dean Crick, Jorge Rocca, Carmen Menoni Mass Spectrometry Imaging (MSI) has played an important role in the direct examination of the chemical composition of complex inorganic and organic samples. Typically a visible/ultraviolet laser is used to ablate the sample and create ions that when detected enables the identification of molecular composition. We report the use of soft x-ray (SXR) lasers in the implementation of a novel laser ablation mass spectrometry (XLAMS) nanoprobe that can probe chemical composition from sample regions of a few attoliters volume and with high sensitivity. The concept exploits: i) high focusability, ii) low penetration depth and iii) high photo-ionization efficiency of the 46.9 nm wavelength SXR laser light. In this work we demonstrate the capabilities of XLAMS to realize chemical contrast imaging with $\sim$ 140 nm lateral and $\sim$ 50 nm depth resolution and high sensitivity. The high lateral and depth resolution and high sensitivity of XLAMS imaging method offer great potential for composition imaging of nanofilms and nanostructures and imaging the chemical distribution of dopants and trace elements. [Preview Abstract] |
Friday, March 7, 2014 8:48AM - 9:00AM |
Y24.00005: A Scanning, All-Fiber Sagnac Interferometer for High Resolution Magneto-Optic Measurements at 820 nm Alexander Fried, Aharon Kapitulnik, Martin Fejer The Sagnac Interferometer, has historically been used for detecting non-reciprocal phenomena, such as rotation. Here we demonstrate a method by which the technique is used as a high resolution method for measuring the Magneto-Optical Polar Kerr effect--a direct indicator of magnetism. Previous designs have incorporated free-space components which are bulky and difficult to align. We improve upon this technique by using strictly fiber-optic coupled optical components and demonstrate operation at a new wavelength, 820 nm, with which we can achieve better than 1 $\mu$rad resolution. Mounting the system on a piezo-electric scanner allows us to acquire diffraction limited images with 1.5 $\mu$m spatial resolution. We also provide extensive discussion on the details and of the SI's construction. [Preview Abstract] |
Friday, March 7, 2014 9:00AM - 9:12AM |
Y24.00006: Measuring shear modulus of individual fibers Herbert Behlow, Deepika Saini, Luciana Oliviera, Malcolm Skove, Apparao Rao Fiber technology has advanced to new heights enabling tailored mechanical properties. For reliable fiber applications their mechanical properties must be well characterized at the individual fiber level. Unlike the tensile modulus, which can be well studied in a single fiber, the present indirect and dynamic methods of measuring the shear properties of fibers suffer from various disadvantages such as the interaction between fibers and the influence of damping. In this talk, we introduce a quasi-static method to directly measure the shear modulus of a single micron-sized fiber. Our simple and inexpensive setup yields a shear modulus of 16 and 2 GPa for a single IM7 carbon fiber and a Kevlar fiber, respectively. Furthermore, our setup is also capable of measuring the creep, hysteresis and the torsion coefficient, and examples of these will be presented. [Preview Abstract] |
Friday, March 7, 2014 9:12AM - 9:24AM |
Y24.00007: Tuning to fast changing phenomena with real-time digital processing Fedor Balakirev A new crop of computationally-intensive digital signal detection techniques brought to light the need for speedier data processing approaches, where conventional data acquisition techniques fall short. We review recent advances in real-time solutions which enable sophisticated fast-feedback detection schemes with sub-microsecond tuning to rapidly changing physical phenomena. The apparatus is particularly suitable for pulsed magnetic field measurements of superconducting critical currents and high-frequency oscillatory signals, among others. [Preview Abstract] |
Friday, March 7, 2014 9:24AM - 9:36AM |
Y24.00008: Nuclear Magnetic Resonance Gyroscope Michael Larsen, Robert Griffith, Michael Bulatowicz The navigation grade micro Nuclear Magnetic Resonance Gyroscope (micro-NMRG) being developed by the Northrop Grumman Corporation (NGC) has concluded the fourth and final phase of the DARPA Navigation Grade Integrated Micro Gyro (NGIMG) program. Traditional MEMS gyros utilize springs as an inherent part of the sensing mechanism, leading to bias and scale factor sensitivity to acceleration and vibration. As a result, they have not met performance expectations in real world environments and to date have been limited to tactical grade applications. The Nuclear Magnetic Resonance Gyroscope (NMRG) utilizes the fixed precession rate of a nuclear spin in a constant magnetic field as an inertial reference for determining rotation. The nuclear spin precession rate sensitivity to acceleration and vibration is negligible for most applications. Therefore, the application of new micro and batch fabrication methods to NMRG technology holds great promise for navigation grade performance in a low cost and compact gyro. This presentation will describe the operational principles, design basics, and demonstrated performance of the NMRG including an overview of the NGC designs developed and demonstrated in the DARPA gyro development program. [Preview Abstract] |
Friday, March 7, 2014 9:36AM - 9:48AM |
Y24.00009: Resistive sensitivity functions for van der Pauw astroid and rounded crosses and cloverleafs Daniel Koon, Ole Hansen We have calculated the sensitivity of van der Pauw resistances to local resistive variations for circular, square and astroid discs of infinitesimal thickness, as well as for the families of rounded crosses and cloverleafs, as a function of specimen parameters, using the direct formulas of our recent paper (Koon \textit{et al}. 2013 \textit{J. Appl. Phys. }\textbf{114} 163710) applied to ``reciprocally dual geometries'' (swapped Dirichlet and Neumann boundary conditions) described by Mare\v{s}~\textit{et al. }(2012~\textit{Meas. Sci. Technol.}~\textbf{23}~045004). These results show that (a) the product of any such sensitivity function times differential area, and thus (b) the ratio of any two sensitivities, is invariant under conformal mapping, allowing for the pointwise determination of the conformal mapping function. The family of rounded crosses, which is bounded in parameter space by the square, the astroid and an ``infinitesimally thin'' cross, seems to represent the best geometry for focusing transport measurements on the center of the specimen while minimizing errors due to edge- or contact-effects. [Preview Abstract] |
Friday, March 7, 2014 9:48AM - 10:00AM |
Y24.00010: Squeeze Flow of Yield Stress Fluids David Pelot, Alexander Yarin The squeeze flow of yield stress materials are investigated using a non-invasive optical technique. In the experiments, cylindrically-shaped samples of Carbopol solutions and Bentonite dispersions are rapidly compressed between two transparent plates using a constant force and the instantaneous cross-sectional area is recorded as a function of time using a high speed CCD camera. Furthermore, visualization of the boundary reveals that the no-slip condition holds. In addition, shear experiments are conducted using parallel-plate and vane viscometers. The material exhibits first a fast stage of squeezing in which the normal stresses dominate and viscosity plays the main role. Then, the second (slow) stage sets in where the material exhibits a slow deformation dominated by yield stress. At the end, the deformation process is arrested by yield stress. The material response is attributed to the Bingham-like or Herschel-Bulkley-like rheological behavior. Squeeze flow is developed into a convenient and simple tool for studying yield stress materials. [Preview Abstract] |
Friday, March 7, 2014 10:00AM - 10:12AM |
Y24.00011: Developing high-resolution carbon-13 and silicon-29 MRI of solids in sedimentary rocks Robert Blum, Sean Barrett, Ravinath Viswanathan, Yi-Qiao Song Mapping pore structure and flow properties of sedimentary rock is directly relevant to current challenges in geophysics like carbon sequestration and oil/gas exploration. Such applications require detailed information about both structure and composition of porous rocks. However, existing scanning methods tend to be limited to gathering one or the other type of information. MRI could be used to measure both composition and structure simultaneously, but conventional MRI in such systems, which targets the proton signal of interstitial fluid, is severely limited by signal losses due to magnetic susceptibility inhomogeneity. Our lab has recently made advances in obtaining high spatial resolution (sub-400 $\mu$m)$^3$ three-dimensional $^{31}$P MRI of bone through use of the quadratic echo line-narrowing sequence (1). In this talk, we describe our current work applying these methods to sedimentary rock, targeting the isotopes $^{13}$C and $^{29}$Si. We describe the results of characterization of limestone and shale samples, and we discuss our progress with producing MRI of these systems. (1) M. Frey, et al. \textit{PNAS} \textbf{109}: 5190 (2012) [Preview Abstract] |
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