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McMorran group March 1, 2016
Front row, left to right: Fehmi Yasin, Quin Konyn (undergrad), Eryn Cangi (undergrad), Saul Propp
Back row, left to right: Alice Greenberg, Tyler Harvey, Jordan Chess, Ben McMorran, Spencer Alexander, Jordan Pierce
Not shown: Galen Gledhill, Cameron Johnson

Prof. Benjamin McMorran, Principle Investigator

Assistant Professor of Physics
Oregon Center for Optical, Molecular, and Quantum Sciences
Materials Science Institute
Department of Physics

Curriculum Vitae

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Alice Greenberg

Graduate Student

I am interested in the parallels between physical optics and the electron phenomena that Ben McMorran studies. In particular, I want to explore interesting beam modes, such as Hermite-Gaussian and Laguerre-Gaussian modes, and their potential applications. Most of my experience is in optics; in the past I have developed optical systems for a scanning tunneling microscope and the electron spectrometer of the KATRIN experiment. Similarly, I am interested in projects developing new optical and electron wave techniques and systems.

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Cameron Johnson

Graduate Student

I am interested in studying the interaction of electron vortex beams with plasmonic nanostructures using energy loss spectroscopy. However, poor beam quality and the low signal to noise ratio of current spectroscopic studies with electron vortex beams have hindered progress in the field. As a result, I have been focused on pursuing different nanofabrication methods to create forked electron diffraction gratings which produce high quality electron vortex beams with a sufficient intensity to perform spectroscopic studies.

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Jordan Pierce

Graduate Student
Project: Electron Spin-to-Orbital Angular Momentum Transfer

My primary work is to develop methods and procedures for manufacturing high quality electron diffraction gratings. Within a Transmission Electron Microscope (TEM), direct control of the transverse beam profile is quite difficult, and traditional TEM regimes seek to have the beam be as plane-wave as possible, limited only by the diffraction through the selecting aperture. Directly controlling the beam profile with electromagnetic lenses is expensive and limited to only the lowest few modes. By utilizing diffractive holograms in the beam column, a wide variety of beam profiles are allowed and can be easily created. However, the process of diffracting an electron beam through a hologram brings with it a number of disadvantages, such as that the diffracted beams are not aligned with the same optical axis as the incident beam, that the energy spread might increase and coherence length decrease, that the intensity in diffracted orders is lowered, and so on. Thus, designing a grating which minimizes the disadvantages and maximizes the utility for a particular application is necessary.

Currently I am focusing on creating ‘apodized gratings’ which have spatially varying diffraction efficiency to better recreate pure modes (such as Laguerre Gaussian or Hermite Gaussian). Future work will be increasing the reliability and scalability of the production process while still improving on diffraction efficiency and beam quality. Below is an example of a binary amplitude fork dislocation grating. The fork dislocation produces beams which have an integer multiple of hbar orbital angular momentum in the diffracted orders.

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Fehmi Yasin

Graduate Student
Project: STEM Holography, Development of an Electron Interferometer

My research is focused on using transmission electron microscopes (TEM) in scanning (STEM) mode to perform electron interferometry experiments. As part of this work our group developed a new technique we call STEM-holography (see figure below), inspired by J.M. Cowley. In addition to working on this technique on the microscope, I spend many hours optimizing the theory and phase reconstruction code for two and three electron beam interference experiments. I will be continuing the development of this technique with Hitachi at their Central Research Laboratory in Hatoyama, Japan next year.

I was lucky enough to teach for my first two years of graduate school, both as a Graduate Employee and a Science Literacy Program (SLP) Fellow. As the latter, I worked with Dr. Ben McMorran to develop curricula and syllabus for a progressive version of PHYS 252-3. We worked towards incorporating a more active learning style during lecture and tutorials via clickers and updated worksheets. I also helped to develop at least half of the exam questions for each exam. Teaching matters!

Additionally, I have developed and coordinated Mad Duck Physics. Since 2014, multiple undergraduate students in the Society of Physics Students (SPS) as well as graduate student volunteers and I have been commuting to River Road Elementary School once a month during their school year to perform hands-on physics and chemistry demos with the students there (usually 3rd through 5th grade). These visits culminate in a field trip that they take to the University of Oregon Physics building, where we perform larger demo shows in addition to smaller hands-on demo stations. Please email me if you’d like to get involved!