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Physical Sciences and Mathematics Commons™
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- Nanoparticles (2)
- Active biological transport (1)
- Air quality -- Mathematical models (1)
- Amines (1)
- Atmospheric aerosols -- Mathematical models (1)
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- Chalcogenides (1)
- Charge exchange reactions (1)
- Climatic changes (1)
- Columbia River -- Tidal currents (1)
- Columbia River Estuary (Or. and Wash.) (1)
- Compound semiconductors (1)
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- Graphene -- Electric properties -- Analysis (1)
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- Physics Faculty Publications and Presentations (10)
- Civil and Environmental Engineering Faculty Publications and Presentations (1)
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- Undergraduate Research & Mentoring Program (1)
Articles 1 - 14 of 14
Full-Text Articles in Physical Sciences and Mathematics
Confined Photonic Mode Propagation Observed In Photoemission Electron Microscopy, Theodore Stenmark, Robert Campbell Word, Rolf Konenkamp
Confined Photonic Mode Propagation Observed In Photoemission Electron Microscopy, Theodore Stenmark, Robert Campbell Word, Rolf Konenkamp
Physics Faculty Publications and Presentations
Using photoemission electron microscopy (PEEM) we present a comparative analysis of the wavelength dependence of propagating fields in a simple optical slab waveguide and a thin film photonic crystal W1-type waveguide. We utilize an interferometric imaging approach for light in the near-ultraviolet regime where a 2-photon process is required to produce photoelectron emission. The typical spatial resolution in these experiments is < 30 nm. Electromagnetic theory and finite element simulations are shown to be in good agreement with the experimental observations. Our results indicate that multiphoton PEEM is a useful sub-wavelength characterization technique in thin film optics.
Entropy Production And Volume Contraction In Thermostated Hamiltonian Dynamics, John D. Ramshaw
Entropy Production And Volume Contraction In Thermostated Hamiltonian Dynamics, John D. Ramshaw
Physics Faculty Publications and Presentations
Patra et al. [Int. J. Bifurcat. Chaos 26, 1650089 (2016)] recently showed that the time-averaged rates of entropy production and phase-space volume contraction are equal for several different molecular dynamics methods used to simulate nonequilibrium steady states in Hamiltonian systems with thermostated temperature gradients. This equality is a plausible statistical analog of the second law of thermodynamics. Here we show that those two rates are identically equal in a wide class of methods in which the thermostat variables z are determined by ordinary differential equations of motion (i.e., methods of the Nosé-Hoover or integral feedback control type). This …
Mixing Times Of Organic Molecules Within Secondary Organic Aerosol Particles: A Global Planetary Boundary Layer Perspective, Adrian M. Maclean, Christopher L. Butenhoff, James W. Grayson, Kelley Barsanti, Jose L. Jimenez, Allan K. Bertram
Mixing Times Of Organic Molecules Within Secondary Organic Aerosol Particles: A Global Planetary Boundary Layer Perspective, Adrian M. Maclean, Christopher L. Butenhoff, James W. Grayson, Kelley Barsanti, Jose L. Jimenez, Allan K. Bertram
Physics Faculty Publications and Presentations
When simulating the formation and life cycle of secondary organic aerosol (SOA) with chemical transport models, it is often assumed that organic molecules are well mixed within SOA particles on the timescale of 1 h. While this assumption has been debated vigorously in the literature, the issue remains unresolved in part due to a lack of information on the mixing times within SOA particles as a function of both temperature and relative humidity. Using laboratory data, meteorological fields, and a chemical transport model, we estimated how often mixing times are < 1 h within SOA in the planetary boundary layer (PBL), the region of the atmosphere where SOA concentrations are on average the highest. First, a parameterization for viscosity as a function of temperature and RH was developed for α-pinene SOA using room-temperature and low-temperature viscosity data for α-pinene SOA generated in the laboratory using mass concentrations of ∼ 1000 µg m−3. Based on this parameterization, the mixing times within α-pinene SOA are < 1 h for 98.5 % and 99.9 % of the occurrences in the PBL during January and July, respectively, when concentrations are significant (total organic aerosol concentrations are > 0.5 µg m−3 at the surface). Next, as a starting …
Ion Transport Across Biological Membranes By Carborane-Capped Gold Nanoparticles, Marcin P. Grzelczak, Stephen P. Danks, Robert C. Klipp, Domagoj Belic, Adnana Zaulet, Casper Kunstmann-Olsen, Dan F. Bradley, Tatsuya Tsukuda, Clara ViñAs, Francesc Teixidor, Jonathan J. Abramson, Mathias Brust
Ion Transport Across Biological Membranes By Carborane-Capped Gold Nanoparticles, Marcin P. Grzelczak, Stephen P. Danks, Robert C. Klipp, Domagoj Belic, Adnana Zaulet, Casper Kunstmann-Olsen, Dan F. Bradley, Tatsuya Tsukuda, Clara ViñAs, Francesc Teixidor, Jonathan J. Abramson, Mathias Brust
Physics Faculty Publications and Presentations
Carborane-capped gold nanoparticles (Au/carborane NPs, 2–3 nm) can act as artificial ion transporters across biological membranes. The particles themselves are large hydrophobic anions that have the ability to disperse in aqueous media and to partition over both sides of a phospholipid bilayer membrane. Their presence therefore causes a membrane potential that is determined by the relative concentrations of particles on each side of the membrane according to the Nernst equation. The particles tend to adsorb to both sides of the membrane and can flip across if changes in membrane potential require their repartitioning. Such changes can be made either with …
An Analysis Of The Optimal Mix Of Global Energy Resources And The Potential Need For Geoengineering Using The Ceagom Model, John George Anasis, M. A. K. Khalil, George G. Lendaris, Christopher L. Butenhoff, Randall Bluffstone
An Analysis Of The Optimal Mix Of Global Energy Resources And The Potential Need For Geoengineering Using The Ceagom Model, John George Anasis, M. A. K. Khalil, George G. Lendaris, Christopher L. Butenhoff, Randall Bluffstone
Systems Science Faculty Publications and Presentations
Humanity faces tremendous challenges as a result of anthropogenic climate change caused by greenhouse gas emissions. The mix of resources deployed in order to meet the energy needs of a growing global population is key to addressing the climate change issue. The goal of this research is to examine the optimal mix of energy resources that should be deployed to meet a forecast global energy demand while still meeting desired climate targets. The research includes the unique feature of examining the role that geoengineering can play in this optimization. The results show that some form of geoengineering is likely to …
An Spm Stage Driven By 3 Stepper Motors, Jianghua Bai, Andres H. La Rosa
An Spm Stage Driven By 3 Stepper Motors, Jianghua Bai, Andres H. La Rosa
Physics Faculty Publications and Presentations
A Scanning Probe Microscope (SPM) stage controlled by 3 stepper motors is designed in this project. The SPM stage controlled by 3 steppers is more versatile than a stage controlled by one motor, but the control of the system is more complicated. In this project, we build the stage actions in an Arduino microcontroller. A finite state machine (FSM) is also built in Arduino to communicate with a PC and an RF controller. A special displaying scheme which has 5 states, is also employed to indicate the operation of the stage. Finally, the SPM stage is fully tested and has …
A Finite Difference Method For Off-Fault Plasticity Throughout The Earthquake Cycle, Brittany A. Erickson, Eric M. Dunham, Arash Khosravifar
A Finite Difference Method For Off-Fault Plasticity Throughout The Earthquake Cycle, Brittany A. Erickson, Eric M. Dunham, Arash Khosravifar
Mathematics and Statistics Faculty Publications and Presentations
We have developed an efficient computational framework for simulating multiple earthquake cycles with off-fault plasticity. The method is developed for the classical antiplane problem of a vertical strike-slip fault governed by rate-and-state friction, with inertial effects captured through the radiationdamping approximation. Both rate-independent plasticity and viscoplasticity are considered, where stresses are constrained by a Drucker-Prager yield condition. The off-fault volume is discretized using finite differences and tectonic loading is imposed by displacing the remote side boundaries at a constant rate. Time-stepping combines an adaptive Runge-Kutta method with an incremental solution process which makes use of an elastoplastic tangent stiffness tensor …
Low-Dose And In-Painting Methods For (Near) Atomic Resolution Stem Imaging Of Metal Organic Frameworks (Mofs), B. Layla Mehdi, A. J. Stevens, Peter Moeck, Alice Dohnalkova, A. Vjunov, John L. Fulton, Donald M. Camaioni, Omar K. Farha, Joseph T. Hupp, Bruce C. Gates, Johannes A. Lercher, Nigel D. Browning
Low-Dose And In-Painting Methods For (Near) Atomic Resolution Stem Imaging Of Metal Organic Frameworks (Mofs), B. Layla Mehdi, A. J. Stevens, Peter Moeck, Alice Dohnalkova, A. Vjunov, John L. Fulton, Donald M. Camaioni, Omar K. Farha, Joseph T. Hupp, Bruce C. Gates, Johannes A. Lercher, Nigel D. Browning
Physics Faculty Publications and Presentations
Metal-organic Frameworks (MOFs) are a group of crystalline and highly porous materials consisting of inorganic metal ions/clusters (nodes) that are coordinated by organic linkers. The ability to create a wide range of porous structures, where the pore size can be easily changed in size and shape offers the potential for many applications in gas storage/separation and catalysis. The presence of the organic linkers or “struts” in the sample creates challenges for high resolution microscopy as the sample itself is very sensitive to beam damage. A key challenge for understanding the structures of MOFs and how the applications can be modified …
The Effect Of Plasma On Graphene Quality In An Inductively Couple Plasma Chemical Vapor Deposition Reactor, Brendan Coyne
The Effect Of Plasma On Graphene Quality In An Inductively Couple Plasma Chemical Vapor Deposition Reactor, Brendan Coyne
Undergraduate Research & Mentoring Program
Despite continued interest in research and application development, full scale graphene production is still limited by many factors including prohibitively high growth temperature requirements. Extremely high quality graphene growth is possible at high temperatures using chemical vapor deposition (CVD). Use of an inductively coupled plasma chemical vapor deposition (ICP CVD) reactor with the benefit of precursor gas decomposition through plasma generation, may provide possibility to reduce growth temperature. Herein, we report plasma’s effects on graphene growth by comparing growths of increasing power supplied to plasma generation and changes in precursor gas ratios. Plasma composition was characterized by ultraviolet and visible …
Essentials Of Building Virtual Instruments With Labview And Arduino For Lab Automation Applications, Jianghua Bai, Andres H. La Rosa
Essentials Of Building Virtual Instruments With Labview And Arduino For Lab Automation Applications, Jianghua Bai, Andres H. La Rosa
Physics Faculty Publications and Presentations
Four ways to improve the capabilities of a virtual instrument involving a microcontroller are covered in this paper. They are structural modeling and programming, real-time control, asynchronous communication between the microcontroller and the host PC, and system integration. This paper covers 4 common problems encountered by embedded developers and 5 solutions to the 4 problems. The solutions and examples demonstrated in this article will help readers build robust and reliable virtual instruments for crucial applications.
Remote Measurements Of Tides And River Slope Using An Airborne Lidar Instrument, Austin S. Hudson, Stefan A. Talke, Ruth Branch, Chris Chickadel, Gordon Farquharson, Andrew Jessup
Remote Measurements Of Tides And River Slope Using An Airborne Lidar Instrument, Austin S. Hudson, Stefan A. Talke, Ruth Branch, Chris Chickadel, Gordon Farquharson, Andrew Jessup
Civil and Environmental Engineering Faculty Publications and Presentations
Tides and river slope are fundamental characteristics of estuaries, but they are usually undersampled due to deficiencies in the spatial coverage of water level measurements. This study aims to address this issue by investigating the use of airborne lidar measurements to study tidal statistics and river slope in the Columbia River estuary. Eight plane transects over a 12-h period yield at least eight independent measurements of water level at 2.5-km increments over a 65-km stretch of the estuary. These data are fit to a sinusoidal curve and the results are compared to seven in situ gauges. In situ– and lidar-based …
Atomic Layer Growth Of Inse And Sb₂Se₃ Layered Semiconductors And Their Heterostructure, Robert Browning, Neal Kuperman, Bill Moon, Raj Solanki
Atomic Layer Growth Of Inse And Sb₂Se₃ Layered Semiconductors And Their Heterostructure, Robert Browning, Neal Kuperman, Bill Moon, Raj Solanki
Physics Faculty Publications and Presentations
Metal chalcogenides based on the C–M–M–C (C = chalcogen, M = metal) structure possess several attractive properties that can be utilized in both electrical and optical devices. We have shown that specular, large area films of y-InSe and Sb2Se3 can be grown via atomic layer deposition (ALD) at relatively low temperatures. Optical (absorption, Raman), crystalline (X-ray diffraction), and composition (XPS) properties of these films have been measured and compared to those reported for exfoliated films and have been found to be similar. Heterostructures composed of a layer of y-InSe (intrinsically n-type) followed by a layer of …
Electrical Properties Of Covalently Functionalized Graphene, Paul Plachinda, David Evans, Raj Solanki
Electrical Properties Of Covalently Functionalized Graphene, Paul Plachinda, David Evans, Raj Solanki
Physics Faculty Publications and Presentations
We have employed first-principle calculations to study transformation of graphene’s electronic structure under functionalization by covalent bonds with different atomic and molecular groups - epoxies, amines, PFPA. It is shown that this functionalization leads to an opening in the graphene’s band gap on order of tens meV, but also leads to reduction of electrical conductivity. We also discuss the influence of charge exchange between the functionalizing molecule and graphene’s conjugated electrons on electron transport properties.
General Approach To Quantum Channel Impossibility By Local Operations And Classical Communication, Scott M. Cohen
General Approach To Quantum Channel Impossibility By Local Operations And Classical Communication, Scott M. Cohen
Physics Faculty Publications and Presentations
We describe a general approach to proving the impossibility of implementing a quantum channel by local operations and classical communication (LOCC), even with an infinite number of rounds, and find that this can often be demonstrated by solving a set of linear equations. The method also allows one to design a LOCC protocol to implement the channel whenever such a protocol exists in any finite number of rounds. Perhaps surprisingly, the computational expense for analyzing LOCC channels is not much greater than that for LOCC measurements. We apply the method to several examples, two of which provide numerical evidence that …