Bulletin of the American Physical Society
18th Annual Meeting of the APS Northwest Section,
Volume 62, Number 7
Thursday–Saturday, June 1–3, 2017; Forest Grove, Oregon
Session H1: Materials & Applications |
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Room: Price Hall 203 |
Saturday, June 3, 2017 1:30PM - 2:05PM |
H1.00001: Extreme High-Field Electron Dynamics in Nanomaterials Invited Speaker: Yun-Shik Lee Light-matter interactions and the dynamics of charged particles are of fundamental scientific interest. In the widely applicable semiclassical theory of light-matter interactions, a Hamiltonian for the light-matter interaction would, in general, take the form, $H=H_0+H_I(t)$, where the Hamiltonian for the matter $H_0$ is independent of time, whereas the interaction Hamiltonian $H_I(t)$ is time-dependent. Under normal circumstances the interaction energy is much smaller than the internal Coulomb energy (1-10 eV for a typical semiconductor), and the time-dependent perturbation theory is sufficient to describe the dynamical processes of light-matter interactions. The perturbation treatment, however, becomes invalid when the light field strength is comparable or even greater than that of the internal Coulomb field of the material. The ultrafast electron dynamics in condensed matter driven by strong electromagnetic waves are largely unknown, even though high-field charge transport and many-body interactions are of great importance for modern science and technology. Understanding and controlling the high-field electron dynamics is indispensable for next-generation high-speed electronic and photonic applications, for which the operating frequency of devices goes beyond 100 GHz and the electric field inside the devices exceeds 100 kV/cm. Recent advances in high-field terahertz (THz) spectroscopy provide unprecedented opportunities to explore the electron dynamics under the extreme conditions. THz radiation lies in the gap between the infrared band and the microwave band in the electromagnetic spectrum. The THz interactions undergo significant qualitative changes in the high-field regime, in which the interaction energy ($H_I=d\cdot E_{THz}$ for electric dipole interactions) is comparable to or even greater than the internal Coulomb energy (e.g., $H_0$~1 eV for a band gap and ~1 meV for intersubband energy level spacing). Furthermore, the relatively long acceleration time in a THz field allows another possibility of extreme light-matter interactions unique in the THz band: the kinetic energy gained by charge acceleration becomes comparable to the unperturbed Coulomb energy of the material. In this strong interaction regime, intense THz pulses excite electrons far from equilibrium and give rise to qualitative changes in optical and electronic properties. The THz excitation and subsequent relaxation takes place on a picosecond time scale, which can be mapped out in the time domain with sub-picosecond resolution by time-resolved THz spectroscopy. High-field electron dynamics in condensed matter is largely influenced by the properties of the material system. We present a few examples of distinctive phenomena of extreme light-matter interactions in different nanomaterial systems: (i) THz control of light-matter coupling in quantum-well microcavities, (ii) High-field THz responses in graphene, (iii) Anisotropic high-field THz response of free-standing carbon nanotubes, and (iv) THz triggered insulator-to-metal transition in a nanoantenna patterned vanadium dioxide film. [Preview Abstract] |
Saturday, June 3, 2017 2:05PM - 2:17PM |
H1.00002: High Field Terahertz Electron Dynamics in Optically excited Carbon Nanotubes Ali Mousavian, Lee Byounghwak, Michael J. Paul, Zachary J. Thompson, Andrew D. Stickel, Yun-Shik Lee Carbon nanotubes (CNTs) have exceptional electrical and optical properties which have inspired unique applications in nanoscale optoelectronics. We present an experimental study demonstrating anisotropic nonlinear THz transmission in free standing multi-walled carbon nanotubes (MWNTs). Unidirectionally aligned free-standing MWNTs form a quasi-one-dimensional semi-metallic structure and exhibit highly anisotropic linear and nonlinear THz responses. Unlike a typical conducting medium in which strong THz pulses induce transparency, intense THz fields enhance absorption in MWNTs, which suggests that strong THz fields efficiently generate charge carriers in MWNTs. We carry out THz time-domain spectroscopy of the MWNT samples for the parallel polarization configuration. We obtain the complex refractive index of the MWNT samples analyzing the amplitude and phase spectra of the transmitted THz pulses and the results agree well with Drude model. Surprisingly, the THz induced absorption does not monotonically increase when the MWNTs are optically excited. THz fields induce transparency at intermediate field strengths (~600 kV/cm), indicating that exotic quantum effects such as resonant quantum tunneling govern the photocarrier dynamics in MWNTs. [Preview Abstract] |
Saturday, June 3, 2017 2:17PM - 2:29PM |
H1.00003: Calculating impacts of fracking proppants through the Port of Olympia E.J. Zita, Zephyra Burt, Tom Crawford Fracking proppants (or fracking sands) are injected into oil and gas fields to enhance recovery of fossil fuels. What are costs and benefits of this process? Manufactured fracking proppants are imported from China through the Port of Olympia to the Bakken oil fields. Scope 3 impacts include carbon due to manufacturing and transporting proppants, fracking operations, and burning the fuels produced. These are not considered by the Port of Olympia, which focuses on Scope 1 and Scope 2 impacts. We calculate select Scope 3 impacts of these fracking proppants, to generate a more complete dataset for evaluating costs and benefits of Port operations. Our calculations may serve to inform future decisions about cargoes at the Port of Olympia. Business goals include financial sustainability, environmental stewardship, and community benefit. This work may assist other Ports and businesses in aligning practices with goals. [Preview Abstract] |
Saturday, June 3, 2017 2:29PM - 2:41PM |
H1.00004: An Integral Equation Coarse-graining Method for Polymer Blends Mohammadhasan Dinpajooh, Marina Guenza We use the variable-level coarse-grained description of polymer melts and the polymer reference interaction site model formalism to study binary polymer blends. In this description, each polymer chain is represented by a single soft sphere or as a collection of multi-blob soft connected blobs. The relation between the center of mass of blobs and real monomer sites is derived by solving a generalized Ornstein Zernike equation. We address the necessity of using an appropriate molecular closure for polymer blends in this formalism. [Preview Abstract] |
Saturday, June 3, 2017 2:41PM - 2:53PM |
H1.00005: Discovery of a Substantial Mathematical and Physical Error in Albert Einstein's Paper 1904 Entitled ``On The General Molecular Theory of Heat'' and Calculating the New Order of Magnitude of the Radiation Wavelengths (black-body radiation) M. Khoshnevisan I have recently discovered a mathematical error in Albert Einstein's derivation [Einstein 1904] $\sqrt[3]{v}=2(\frac{\sqrt[3]{k}}{\sqrt[3]{c}})\frac{1}{T}.$ Einstein's prediction (0.420/T) for the order of magnitude $\lambda { }_{m}$is incorrect. I have derived the correct form of equation 28, and calculated the new value for the order of magnitude of the radiation wavelengths as (0.263/T). This new value is based on the solution of the first order differential equation, $\int {\frac{d\overline E }{\left( {\overline E } \right)^{2}}} (2k)=\int {\frac{dT}{T^{2}}} $. Einstein's has also made a physical error by not applying the correct laws of physics. Correcting this mathematical error shows that Einstein's prediction is more accurate than he thought during his life time.\\ \\I would like to express my appreciation to Dr Stefan Hildebrandt, Editor-in-Chief of Annalen der Physik for his very useful comments via e-mail. I also would like to express my gratitude to Professor Lyman Page, Chair of the Department of Physics at Princeton University, Professor David J. Gross, Nobel Laureate in Physics and Vice President of the American Physical Society, and Professor Homer Neal, former President of the American Physical Society and Professor of Physics at University of Michigan for their time and helpful oral suggestions. [Preview Abstract] |
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