Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session X23: Novel Sensors and Instrumentation |
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Sponsoring Units: GIMS Room: BCEC 158 |
Friday, March 8, 2019 8:00AM - 8:12AM |
X23.00001: Mass and Stiffness Spectrometry of 20-nm Gold Nanoparticles by Nanoelectromechanical Systems Ezgi Orhan, Mert Yuksel, Atakan Ari, Cenk Yanik, Utku Hatipoglu, Mustafa Kara, Selim Hanay Nanoelectromechanical systems are highly sensitive to adhered particles, and by using frequency shifts caused by particle adhesion on the surface of the resonator, it is possible to obtain stiffness of the adsorbate in addition to its mass and position on the resonator. In order to conduct our experiments, we fabricated NEMS resonators using top-down fabrication techniques. We have measured their multimode resonance response using electrothermal actuation and piezoresistive detection. Matrix Assisted Laser Desorption and Ionization (MALDI) is implemented to deliver particles towards the resonator. We have detected and characterized, in-real time, 20-nm gold nanoparticles using the first four out-of-plane modes. Simultaneous measurements of multiple modes were accomplished using phase-locked loop circuits running in parallel. By using the frequency shifts of resonance frequencies, we propose a method in which we assume the analytes adhered on the beam are hemispherical to obtain mass and stiffness, size and positions of the analytes. The size and position values for individual nanoparticles obtained were verified with independent characterization under SEM. The measurements provided here confirms the utility of multimode NEMS detection technique with analytes down to 20 nm radius. |
Friday, March 8, 2019 8:12AM - 8:24AM |
X23.00002: Nonlinear Interferometer for Complex Spectral Measurement: a Sensitive Probe of Complex Interfaces Mary Shultz, Joam Marmolejos, Patrick Bisson Soft interfaces are common in biology, the environment, and technological applications. Probing these, particularly when the interface is buried between two condensed phases presents many challenges. The only current method available for probing such interfaces with molecular specificity is the vibrational spectroscopy, sum frequency generation (SFG). SFG attains surface sensitivity due to its nonlinear nature. Due to nonlinearity, separating overlapping signals is difficult, usually leading to nonunique separation. This problem has long been recognized by SFG practitioners and several methods for determining the complex components of the signal have been devised. None produce an absolute measurement of the complex signal. This contribution reports a nonlinear interferometer, that not only addresses this issue but also complex measurement issue, but also detects even low concentration interfacial species. The nonlinear interferometer has been demonstrated in both scanning and broadband SFG systems. This contribution reports on results from thin film and other interfaces. Specifically, we show that the conformation of molecules in a hydrophobic interface are significantly altered by water in the film. |
Friday, March 8, 2019 8:24AM - 8:36AM |
X23.00003: Project Mjolnir: High efficiency real time mass spearator and ion trap Jason Burke, Barbara Alan, Aaron Hellinger A low energy mass separator and ion trap for the real time separation and trapping of radioactive isotopes has been developed. The apparatus consists of an ultra-high purity helium buffered electrostatic recoil gas stopper and RF carpet to guide ions from a radioactive source to the exit aperture. A natural helium jet created at the exit imparts momentum to the ions. The ions enter a large acceptance radio-frequency quadrupole ion guide which has a DC gradient applied to it. The ions are cooled in the residual helium buffer gas are damped and collimated and continuously injected into a quadrupole mass separator (QMS). Ions are mass and charge selected in the QMS and exit into another RFQ for further beam collimation before being injected into a linear ion trap. The entire apparatus has been designed to be able to continuously load the ion trap. The ion trap is physically small allowing a large solid angle to be covered by detectors to study of short-lived isomers. Project Mjolnir latest status will be presented. |
Friday, March 8, 2019 8:36AM - 8:48AM |
X23.00004: Effective Realtime Data Processing using LabJack T-Series DAQs Benjamin Montgomery, Paul Nakroshis The ability to accurately collect and computationally process data from sensors in real time is crucial to many scientific experiments. This generally leads to cost-ineffective solutions from well-known manufacturers, usually tied to proprietary analysis software, or oft-crude home-built alternatives. In light of this issue, we have created an open-source python API for the LabJack T-series of DAQs as a powerful, cost-effective alternative that is extensible and accessible to users with varying backgrounds in programming. We demonstrate the efficacy of this interface in the context of gathering and processing data from a quadrant-cell photodiode used to monitor a torsion pendulum in real time, as well as highlighting a few notable advantages found processing data with the LabJack. |
Friday, March 8, 2019 8:48AM - 9:00AM |
X23.00005: Measuring Hall Conductivity Using a Cantilever Torque Magnetometer Tiffany Paul, Samuel Mumford, Amir Yacoby, Aharon Kapitulnik We present Hall conductivity measurements of Corbino-disk patterned thin film samples on a cantilever-based torque magnetometer. When a voltage is applied across the sample and a magnetic field is applied through the sample plane, the Hall current provides a magnetic moment that interacts with the external magnetic field and yields a torque on the end of the cantilever. The symmetry of this technique eliminates contributions from longitudinal resistance, making Hall conductivity measurements of previously inaccessible materials possible. Following a demonstration of how we determine the elastic properties of the cantilever system, we discuss various realizations of the technique, including for transverse thermoelectric currents, and show preliminary results on simple electronic systems. |
Friday, March 8, 2019 9:00AM - 9:12AM |
X23.00006: Increase the sensitivity of magnetoelastic sensors by modifying the sensor geometry Paula Gonzalez, David Gandia, Andoni Lasheras, Iban Quintana, Jon Gutierrez, Maria Isabel Arriortua, Ana Catarina Lopes
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Friday, March 8, 2019 9:12AM - 9:24AM |
X23.00007: Optimal Optical Systems for Collecting Photoluminescence of Point Emitters Juan Lizarazo Ferro, Rashid Zia Many applications that leverage optics, and explorations in fundamental physics, are limited by the experimenter’s ability to collect luminescence from point emitters embedded in solid state hosts. Here we explore the limitations imposed by the common type of optical systems used for this purpose, and we compare them against proposed alternative designs. In addition to comparing their collection efficiency, these new designs are also analyzed for tolerance in the lateral and axial position of the emitters with respect to reference auxiliary surfaces or alignment guides. Ray-optics and FDTD simulations will be used to quantify the proposed alternatives. Both an objective composed of spherical surfaces and a metalens implementation will be presented. |
Friday, March 8, 2019 9:24AM - 9:36AM |
X23.00008: Fast Reflective Optic-Based Rotational Anisotropy Nonlinear Harmonic Generation Spectrometer Jason Dinh Tran, Baozhu Lu, Darius Torchinsky Rotational anisotropy second harmonic generation (RA-SHG) has emerged as effective probe of structural and electronic symmetry of hard condensed phase systems, as well as a spectrocsopic tool for investigating the energy-dependent nonlinear electronic properties of solids. A common implementation of this technique has involved sample rotation to obtain the maximal number of nonlinear susceptibility coefficients, leading to signficiant challenges in experimental alignment which have recently been overcome by diffractive optic-based approaches. However, the same diffractive optics that have opened up this metrology to a variety of new sample configurations have also restricted the RA-SHG spectrometer in both data acquisition speed and broadband spectroscopic capability. We describe the design and application of an RA-SHG spectrometer based almost entirely upon reflective optics that overcomes the wavelength-dependent shortcomings of current state of the art RA-SHG devices and provide examples of the apparatus' application to a variety of test samples. |
Friday, March 8, 2019 9:36AM - 9:48AM |
X23.00009: Fourier Domain Rotational Anisotropy Second Harmonic Generation Baozhu Lu, Darius Torchinsky We describe a novel scheme of detecting rotational anisotropy second harmonic generation (RA-SHG) signals using a lock-in amplifier referenced to a fast scanning RA-SHG apparatus. The method directly measures the nth harmonics of the scanning frequency corresponding to SHG signal components of Cn symmetry that appear in a Fourier series expansion of a general RA-SHG signal. We will present measurements on a GaAs test sample to compare point-by-point averaging with the lock-in based method. We will discuss how, when divided by the C∞ signal component, the lock-in detected data allow for both self-referenced determination of ratios of Cn components of up to 1 part in 104 and significantly more sensitive measurement of the relative amount of different Cn components when compared with conventional methods. |
Friday, March 8, 2019 9:48AM - 10:00AM |
X23.00010: High-Pressure Laser Floating Zone Furnace Julian Schmehr, Michael Aling, Eli Zoghlin, Stephen Wilson The floating zone technique is one of the most established methods in growing single crystals for materials research applications, due to its propensity to produce large, extremely high quality specimens. However, limitations in the ultimate pressures of growth atmospheres in standard furnace designs renders many compounds not suitable for crystal growth employing the floating zone technique, either due to excessive volatility or metastability. Here we demonstrate a high pressure laser floating zone system which pushes the envelope of processing pressure for this technique. Focused laser light allows for extremely sharp heating gradients, uniform radial heating profiles and high processing temperatures. In turn this allows for the implementation of a high strength metal growth chamber, allowing for greatly enhanced processing pressures. We demonstrate successful single crystal growths of a range of oxide compounds up to 10 kpsi applied gas pressures, a more than two-fold increase in processing pressures compared to commercially available floating zone systems. |
Friday, March 8, 2019 10:00AM - 10:12AM |
X23.00011: Advancing Silicon Atomic-Scale Applications Roshan Achal, Mohammad Rashidi, Jeremiah Croshaw, David Churchill, Marco Taucer, Taleana Huff, Martin Cloutier, Jason Pitters, Robert A Wolkow Dangling bonds (DBs) on the surface of hydrogen-terminated silicon present an attractive basis for next generation atomic scale devices as they possess both ideal electronic properties and high thermal stability. One of the ultimate applications of DBs is the creation of atomic scale logic circuitry, where designs may reduce power consumption by several orders of magnitude. We use a Scanning Tunneling Microscope (STM) to fabricate proto-devices and other DB-based structures. Recent developments in the precise fabrication of DBs have enabled significant progress towards this goal. With these developments, new applications of DBs are also emerging. In one such application we demonstrate the use of DBs to store information at the atomic scale, including the ability to read out the information. Further, we demonstrate the potential to advance site selective chemistry on the surface through the reliable creation of reactive sites. |
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