Image result for oregon state universityDepartment of Physics Yunker Lecture Poster Session

Welcome to the Oregon State Department of Physics,
April 20th 3:30-4:30 pm, Weniger 328

[Light refreshments will be served]

Technical Program

Experimental Physics Labs (Primarily Lab-Based Groups)

LAB Poster Technical Information
1) Qiu
Single molecule characterization of an orphan kinesin AtPAKRP2
[Biophysics] Allison Gicking, Pan Wang, Keith Mickolajczyk, William O. Hancock, Lijun Guo and Weihong Qiu
Kinesins are microtubule-based motor proteins that play important roles in intracellular transport. Orphan kinesins outside the 14 well-recognized subfamilies (kinesin-1 through kinesin-14) are poorly studied. Here, we show using single-molecule fluorescence microscopy that PAKRP2 – an orphan kinesin that putatively transports vesicles for cell plate formation in the model plant Arabidopsis thaliana – can take many sequential steps to microtubule plus-ends without the aid of clustering or a non-motor microtubule binding domain. Furthermore, using high-resolution nanoparticle tracking we find that PAKRP2 achieves processive motility by frequently stepping laterally to adjacent microtubule protofilaments, likely due to its long neck linker. Collectively, our study reveals PAKRP2 as the first orphan kinesin to demonstrate processive plus-end-directed motility as a homodimer and thus, broadens our understanding of the diverse kinesin stepping mechanisms
2) Graham

Controlling interlayer electronic pathways in stacked van der Waals materials

Kyle Vogt, Hiral Patel, Sufei Shi, Matt W. Graham

[Optics, cond matter] ABSTRACT: We use novel ultrafast probes to discover new interlayer electronic extraction pathways in graphene-like systems including twisted bilayer graphene (tBLG) and transition metal dichalcogenides (TMD).  In tBLG, we show the emergence of twist angle-tunable absorption peaks result from rehybridization of constrained interlayer 2p orbitals to form bound exciton states. Specifically, we use one and two-photon transient absorption microscopy and photoluminescence to directly image strongly-bound exciton states that arise from a prominent ghost-Fano resonance effect. This observation of strongly bound excitons is unusual for a metallic system and substantially increases boths graphene’s carrier lifetime, and photocurrent extraction efficiency.   Unlike graphene, semiconducting 2D TMDs like WSe2, have long carrier lifetimes, but challenging mobility and exciton dissociation bottlenecks that inhibit photocurrent extraction.  By combining femtosecond resolved photocurrent microscopy with ultrafast transient absorption microscopy, we have selectively imaged the rate-limiting exciton-dissociation bottlenecks that intrinsically inhibit photocurrent production in stacked TMD devices.  We demonstrate our unique ultrafast methods selectively isolate the ultrafast dynamics relevant to ‘on-chip’ photocurrent generation, and are being extended to measure coherent exciton dynamics using a near-field four-wave-mixing microscopy approach
  Fun Group Fact: Our lab enjoys making fundmental optical physics practical by looking at 'on-chip' devices, sensors and solar cells. Industry appreciates our novel approach; awarding us the most corporate-backed grants of any new-PI assistant prof OSU Lab. group link
3) Lee Ultrafast Photocarrier Dynamics in Single-Layer Graphene Driven by Strong Terahertz Pulses
[Optics, cond matter]
Ali Mousavian, Byounghwak Lee, Andrew D. Stickel, and Yun-Shik Lee
  ABSTRACT: Strong THz fields and photoexcitation simultaneously enhance the THz transmission of graphene mainly due to the increase of carrier scattering rates. The relaxation of photocarriers, on the other hand, shows opposite effects of the THz fields and photoexcitation. Photoexcitation increases the relaxation time via the reabsorption of optical phonons by photocarriers, while strong THz fields reduce the relaxation time because the field induced redistribution of electrons opens up unoccupied states in the conduction band and consequently enhances the relaxation and the phonon emission.
4) Ostroverkhova

Molecular packing-dependent exciton and polariton dynamics in anthradithiophene organic crystals

Jonathan Van Schenck, Gregory Giesbers, Akash Kannegulla, Li- Jing Cheng, John E. Anthony, Oksana Ostroverkhova

[Optical materials physics] The Organic Photonics and Electronics Lab
Organic semiconductors have long been an incising alternative to inorganic SC because of the relative ease with which OSCs can be processed and their lower costs. Recent developments in the field have made OSC even more useful in the context of organic devices with demonstrations like charge carrier mobility exceeding 10 cm2/Vs and power conversion efficiencies exceeding 10%. In addition to these material property improvements, recent attempts to couple organic excitons to photon modes have reached the strong (and in some cases the ultra-strong) coupling regime—leading to the development of organic-based polaritonic devices. These hybridized light-matter states have opened up a host of new and exciting phenomena to study, like low-threshold polariton lasing and polariton Bose-Einstein condensation. While these exotic phenomena have been investigated, there are still many unanswered questions about organic polaritons. One such question revolves around the interplay between intermolecular coupling in organic crystals and light-exciton coupling. We present an analysis of how intermolecular coupling affects the coupling between photon modes and excitons in the context of functionalized antradithiophene (ADT) derivatives.

Many of these ADT derivatives have identical optical properties in solution, but by attaching different side groups to the molecular backbone, one can change the crystal packing structure. In this way, ADT derivatives are a perfect set of test systems to isolation the crystal-induced effects on excitons. The shift from solution to crystal phase is characterized by the effective intermolecular coupling (J0). The traditional categories for types of coupling are J (for negative J0) and H (for positive J0) aggregates. Recently, we have shown that the effective intermolecular coupling in crystalline ADT molecules is strongly anisotropic. In polarization-dependent absorption spectra of molecules like diF-ADT-TES and diF-ADT-TDMS, the sign of this effective coupling can reversed along different crystal axes. This allows us to freely switch between J- and H-like aggregation signals within the same crystal. This newly discovered J/H aggregate switching has important implications for OSC devices in general, but is especially interesting in the context of polaritonic devices.
5) Ostroverkhova

Fungi-Derived Pigments for Sustainable Organic (Opto)Electronics

Gregory Giesbers, Jonathan Van Schenck, Sarath Vega Gutierrez, Sara Robinson, Oksana Ostroverkhova

[Optical materials physics]

Organic Photonics and Electronics Group
ABSTRACT: Organic semiconductor materials are becoming more of interest for use in optoelectronic applications due to their low cost, solution processability, and tunable properties. We present a study of the optical and electronic properties of a novel class of material, fungi-derived pigments. Fungi-derived pigments are a naturally sourced, sustainable class of materials that are completely unexplored as organic semiconductor materials. One such pigment is xylindein, which is secreted from the fungus Chlorociboria Aeruginascens.
HOMO LUMO energies of xylindein are determined from electrochemical measurements and related to previous DFT calculations performed using Gaussian 09. I-V characteristics of xylindein are measured using a Keithley 237 source-measure unit. Looking at the space-charge-limited current (SCLC) regime of the I-V curve, where the curve transitions from linear to quadratic, we determine the charge carrier mobility, expanding upon previous estimates.


6a) Minot

[Cond matter physics]

Stretchable Graphene Transistors for High Signal, High Channel Count Neural Recording

Morgan A. Brown, Kathryn L. McGill, Micheal Crosser, Paul L. McEuen, Jesse H. Goldberg, Ethan D. Minot
6b) Minot

[Cond matter physics]

Highly efficient carbon nanotube photodiodes enabled by field-enhanced exciton dissociation

Daniel McCulley, Mitchell Senger, Ethan Minot


Nanoelectronics Lab
ABSTRACT: Pristine, defect-free, suspended carbon nanotubes (CNTs) are an ideal system to study photocurrent
generation in the limit of strong Coulomb interactions. Photon-to-electron conversion efficiencies exceeding 100%
have already been shown in quantum dot solar cells, and carrier multiplication effects have been reported in CNT
photodiodes. However, measurements of CNT photodiodes have so far yielded disappointing internal quantum
efficiencies (< 70%). Our experiments utilize fully-suspended dual-gated carbon nanotubes with axial electric fields up
to ~ 15 volts per micron. Building on our past results (Aspitarte, Nano Letters 2016), we use stronger electric fields to
increase the exciton dissociation rate and unlock the possibility of harnessing carrier multiplication. We present our
recent progress toward demonstrating internal quantum efficiencies greater than 100%.

7) Sun

Decoding Cellular Body Language

Chris Eddy, Bo Sun


Cell Biophysics Group
ABSTRACT: Cell morphology has long been a crucial biomarker of cellular pathology, markedly so in cancer. We study the morphology of highly invasive MDA-MB-231 GFP cells in varying densities of 3D type I collagen matrices by first investigating the geometrical properties of cells. Then, using machine-learning and deep-learning techniques, we classify the cells into distinct phenotypes based on protrusion formations to investigate how cell phenotypes assist in real-space migration. We find that the observed population geometric features are not affected by varying environment density but do display different dynamic characterizations. Using support-vector machine learning we reveal unique depictions of cell phenotype dynamics in different collagen densities.


Fun Lab facts: What makes our group special is we integrate many different experimental techniques to solve complex biological problems, rather than being confined to one domain of research. Our work uses optical and magnetic tweezers, various fluorescence microscopy methods, clean-room fabrication of microfluidic devices, machining, computational modeling, image analysis, and state-of-the-art machine-learning and deep-learning techniques. This breadth is arguably unique to our research group and is necessary for the types of questions we seek to answer in our lab.

8a) Tate

The effect of amorphous precursors on the crystallinity of TiO2 thin films using Pulsed Laser Deposition

James E.S. Haggerty, Bethany Matthews, Janet Tate, Laura T. Schelhas, Kevin H. Stone, Michael F. Toney, Lauren Garten, John Perkins, David S. Ginley, Vladan Stevanovic, Brian P Gorman, Kirill Popov, Daniil Kitchaev, Wenhao Sun, Gerbrand Ceder

[Materials physics] ABSTRACT: Polymorphism is the ability of a material to adopt a different crystal structure while maintaining stoichiometry.  Titania (TiO2) is a well-known transparent metal oxide with three primary polymorphs, rutile, anatase, and brookite.  It is used in many applications ranging from photocatalysts, cosmetics, gas sensors, and the biomedical industry.  We aim to understand the pathways by which TiO2 transforms into the metastable brookite polymorph and how it is affected by the presence of the metastable anatase and stable rutile polymorphs.  We study theoretically helper-ion incorporation, substrate matching, and chemical transformation to guide synthesis of brookite thin films.  Amorphous thin films are deposited on SLS-glass, ThOx on Si, and YSZ(110) substrates by pulsed laser deposition under different conditions to explore the nature of different amorphous precursors on the crystallization of the polymorphs.  Structural characterization by X-ray diffraction is performed in-situ during rapid and conventional annealing and reveals the formation of brookite upon heating to 340°C and subsequent partial conversion to anatase upon cooling.  Micro-Raman spectroscopy and atomic force microscopy together map the micron scale regions of the pure polymorphs.  TEM is used to examine whether ion incorporation from the substrate contributes to the formation of brookite. 
  Fun Group Fact: Our group collaborates with scientists from all over the country.  Also, we like to blow things up in vacuum chambers.
8b) Tate

Amorphous to Crystalline Polymorphic Behaviors of TiO2 Thin Films Deposited Under Various Pressures by Pulsed Laser Deposition

Okan Agirseven, James E.S. Haggerty, Janet Tate, Laura T. Schelhas, Michael F. Toney, Lauren Garten, John Perkins, David S. Ginley, Brian P Gorman, Daniil Kitchaev, Wenhao Sun, Gerbrand Ceder

[Materials physics] ABSTRACT: TiO2 is a versatile wide bandgap transparent semiconducting oxide with three well known polymorphs; anatase, rutile and brookite. TiO2 thin films deposited at room temperature with PLD (Pulsed Laser Deposition) have amorphous precursors that can transform into these crystalline TiO2 polymorphs by proper annealing; thus allowing us to control and investigate the polymorphic behaviors and phase progression in detail. These crystalline end products are desired for many industrial applications mainly for their photocatalytic activity, such as degradation of organic wastes. Our research aims to understand the formation behavior of these metastable polymorphs of TiO2 as related to the precursor structure. In this study, TiO2 thin films are deposited at room temperature on fused silica substrates by pulsed laser deposition under different pressures with various oxygen gas concentraions. Microstructural properties of the films are investigated by XRD, Raman spectroscopy, SEM, XPS, and optical transmission and reflection spectroscopy. We found that both total pressure and the relative oxygen concentration during deposition have different impacts on the end products with variable phase fractions and phase structures containing rutile, anatase and brookite.
  Fun Group Facts: Our group mainly focuses on deposition and modification of materials in thin film form. For our research, we use lasers, plasma, x-rays, electrons, high vacuum, high temperature, optics, electronics and many other interesting processes that let us work as frontiers on physical possibilities in materials.


Theoretical & Computational Physics
Physics Education Research (PER) Groups

GROUP Poster Technical Information
1) Lazzati
Demystifying the Observed Gamma Ray Burst Tracking Between the Peak Energy and Luminosity
[Astrophysics] Tyler Parsotan,  Shigehiro Nagataki, and Davide Lazzati
  ABSTRACT: Long Gamma Ray Bursts (LGRBs) are extremely energetic and mysterious objects. When they are detected, thier light curves and time resolved peak energies are sometimes observed to follow, or track, one another. Alternatively, there can be a global hard-to-soft evolution of the peak energy or even no trend at all. This chacateristic can be emulated using Monte Carlo simulations of the radiation propagating through a LGRB jet, allowing us to investigate the cause of this observed, yet unexplained, behavior.
  Fun Group Fact: Our group hosts the Astronomy Open House outreach events where we invite the public to do demos that help explain astrophysical phenomenon.
2a) Gire
Student Sense-making on Homework in a Sophomore Mechanics Course

Kelby T. Hahn, Paul J. Emigh, MacKenzie Lenz, Elizabeth Gire
[PER] ABSTRACT: When students solve physics problems, physics instructors hope that they use and interpret algebraic symbols in coordination with their conceptual understanding, their understanding of geometric relationships, and their intuitions about the physical world. We call this process physics sense-making. ``Plug-and-chug'' and ``template'' problem solving strategies, which are common for many students, exclude sense-making. We have designed a mechanics course for sophomore, undergraduate students that emphasizes sense-making and traditional physics content in equal measure. Sense-making is supported in all aspects of the course: during in-class activities, on augmented homework assignments, and on exams. While sense-making prompts on homework assignments are strongly scaffolded at the beginning of the course, these supports fade as the course progresses. In this paper, we discuss an analysis of students' homework responses to open-ended sense-making prompts throughout the course.
2b) Gire

Student perspective of and experiences with sense-making: a case study

MacKenzie Lenz, Kelby T. Hahn, Paul J. Emigh, and Elizabeth Gire

[PER] OSU Physics Education Research Group
ABSTRACT: One difference between expert and novice problem-solvers is their use of sense-making strategies. Sense-making while solving physics problems involves coordinating the use of algebraic symbols with conceptual understandings, understandings of geometric relationships, and intuitions about the physical world. We have developed a new sophomore-level course that explicitly supports students in using various sense-making strategies in the context of classical mechanics and special relativity. This poster examines one student whose sense-making performance improved dramatically throughout the course. We present an analysis of a series of interviews with this student, his homework, and his pre- and post- sense-making assessments. While he reports having been familiar with many of the sense-making strategies emphasized in the course, he discusses several ways his use of these strategies was enriched. We see evidence of this shift in his written coursework.
2c) Gire, Manogue, Roundy
Paradigms in Physics
A Learning Progression for Partial Derivatives

Corinne A. Manogue, Tevian Dray, Paul J. Emigh, Elizabeth Gire, David Roundy
[PER] ABSTRACT: We describe a learning progression for partial derivatives spanning virtually all undergraduate courses in calculus and physics.  Our learning progression begins with an idealized trajectory for students to follow as they learn partial derivatives, based on extensive discussion with content experts.  The learning trajectory does not consist solely of the content that students learn, but details a particular sequence of experiences that build on each other as students move from one course to another.  The overall trajectory includes a broad set of classroom activities designed to foster student learning using various strategies for interactive engagement.  We then empirically evaluate the learning progression by researching student understanding of partial derivatives at key points along the trajectory.
2d) Gire, Roundy, Manogue

Analogues in Thermodynamics: Legendre Transformations and the Partial Derivative Machine

Michael Vignal, Corinne A. Manogue, David Roundy, and Elizabeth Gire

[PER] Physics Education Research Group

3) Schellman

Deep Underground Neutrino Experiment (DUNE) Near to Far Neutrino Beam

Amit Bashyal & Heidi Schellman on behalf of the DUNE collaboration

[High-Energy Computational] Neutrino Group
ABSTRACT: The DUNE near detector will be used to characterize the LBNF neutrino beam and to predict the neutrino fluxes at the DUNE far detector. Because of the different detector locations with respect to the beam-line, energy spectra at the two detectors will be slightly different, even in the absence of neutrino oscillations. A method known as  the beam matrix method attempts to improve on the simple near/far ratio method of flux extrapolation by using a two dimensional map of near detector spectra to far detector spectra. I will show the impact of this method on neutrino flux predictions at the DUNE far detector
  Fun group facts: Students in our group both help build the next large neutrino experiment (DUNE) and analyze data from the MINERvA neutrino cross section experiment 300 ft below Fermilab in Batavia IL.  See for updates on what we are doing.

Instructions to Presenters

Please setup your poster in 328 on easels provided. Alternatively your poster may be affixed to walls using approved tape provided.