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Author: Kayla Benson

Kilbey Group Alumni Recognized at ACS

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Dayton Street

 

 

Dayton Street earned his PhD in the University of Tennessee’s Department of Chemistry during the spring and was one of six selected as a finalist for the Eastman Chemical Student Award in Applied Polymer Science, and as part of this, he presented aspects of his dissertation research at the Fall ACS meeting. Dayton is a National Research Council (NRC) postdoctoral fellow at the Air Force Research Laboratory.

Graham Collier

 

 

Graham Collier earned his PhD in 2017 and was selected for inclusion in the PMSE Future Faculty symposium at the Fall ACS meeting. Graham is currently a postdoctoral research scientist at Georgia Tech.

Department Welcomes New Faculty Member

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Fred Heberle Aug. 2019
Photo by Steven Bridges

Fred Heberle joined the Department of Chemistry as an assistant professor. Heberle comes from a small town in eastern Montana, and earned his PhD at Cornell University in the lab of Gerald Feigenson. Heberle spent five years in the Neutron Sciences Division at Oak Ridge National Laboratory for his postdoctoral research and is a PI on an NSF grant for the study of asymmetric membranes. 

“Our lab uses biophysical, biochemical, and computational methods to answer fundamental questions about biomembrane structure and organization,” Heberle said. “We use model systems spanning a vast range of complexity, from simple liposomes made from a single type of lipid, to multicomponent vesicles with engineered lipid asymmetry, to the plasma membrane of a living cell itself. We use techniques ranging from calorimetry, to fluorescence, to neutron and X-ray scattering.”

Feigerle Gives Talk About Diamond Foils for ORNL’s SNS

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Chuck Feigerle, head of the Department of Chemistry at the University of Tennessee, Knoxville, spent a summer learning how to make diamond films with Jim Butler from the Naval Research Laboratory in Washington, D.C. Feigerle and his associates grew the first diamond films for Buehler Hall’s Spallation Neutron Source (SNS). Then, with Department of Energy funds, a microwave plasma reactor was purchased for Bob Shaw’s lab at ORNL, where diamond foils were grown and tested for the SNS over the next few years. Shaw and Feigerle led the research group. He credits Leslie Wilson with carrying out much of the research.

 Each foil is grown by chemical vapor deposition on a silicon wafer formed to have a desired corrugated surface pattern that makes the film rigid. The silicon substrate is dissolved away using acid, leaving just enough to serve as a handle for mounting the foil.

diamond foils

Feigerle spoke about ORNL and UT research in developing and testing this key component of the SNS in a recent talk.

The SNS employs nanocrystalline diamond foils made at ORNL to strip the electrons from negatively charged hydrogen atoms in a beam accelerated to almost 90 percent the speed of light.

Feigerle presented results on the development and use of nanocrystalline diamond stripper foils at the SNS. He described studies at ORNL of the transformations that occur in crystalline structure, emissivity and the carbon state of the foils from deposition of beam energy into the foil.

One finding is that after long exposure to high beam currents that increase the temperature to above 1,500 degrees Celsius, the diamond foils become more like a graphite, gray, crystalline, form of carbon used as a solid lubricant, in pencils and as a moderator in nuclear reactors (e.g., the Graphite Reactor, the world’s first continuously operated reactor that originally made ORNL famous).

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Calhoun Lab Illuminates ‘Dark’ States in Nano Letters Paper

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Researchers in the Department of Chemistry at the University of Tennessee, Knoxville, are shooting lasers at quantum dots to illuminate ‘dark’ states and provide new insights that can steer the design of future materials.

Tiny crystals known as quantum dots have become so ubiquitous that you can find them in modern commercial televisions. Yet there are still key questions that have remained unanswered despite decades of research about how these crystals work. In particular, it is not clear exactly how the surfaces of quantum dots affect how they interact with light.

When light hits a quantum dot, the energy is stored in energy levels or states. When this energy moves to states on the surface of the quantum dot, it becomes “trapped” and lost for potential use. These surface states, however, are invisible to basic optical experiments because they cannot directly absorb the light, and this leaves the energies of these surface states unknown.

That was until a collaborative UT/Oak Ridge National Laboratory research team, led by Tessa Calhoun in the University of Tennessee’s Department of Chemistry, developed a new way to shed light on them. Their electronic sum frequency generation microspectroscopy technique simultaneously mixes different colors of ultrashort laser pulses to generate new colors of light that describe these elusive ‘dark stats’ on the quantum dots and is detailed in their recent paper published in Nano Letters.

“I was excited by just how many energy levels we could detect with a single measurement at ambient conditions,” Calhoun said.

In addition to being able to match dozens of known energy levels from literature, their studies were able to detect multiple elusive surface states.

“While many other experiments had suggested the presence of one or more of these states, we are the first to be able to directly show that there is more than one surface state in these quantum dots.” Calhoun said.

In addition to Calhoun, other team members were Brianna Watson, the lead author, and Benjamin Doughty, a staff scientist in the Chemical Sciences Division at ORNL. Brianna was a graduate student in the UT Department of Chemistry and is now conducting postdoctoral research using microscopy at Boston Children’s Hospital.

This new information about the energies of dark states promises to provide an avenue to control these generally undesirable defects to improve performance in devices.

Knowing more about these surface states will allow scientists to design better nanoparticles and Calhoun’s group is excited for the future systems they can explore with their new microspectroscopy.

Read more about this research in the paper titled “Energetics at the Surface: Direct Optical Mapping of Core and Surface Electronic Structure in CdSe Quantum Dots using Broadband Electronic Sum Frequency Generation Microspectroscopy.” 

Dai Selected Winner of 2020 Max Bredig Award

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Dai wins Electrochemical Society’s Max Bredig Award Prof. Sheng Dai has been selected as the winner of the 2020 Max Bredig Award in Molten Salt and Ionic Liquid Chemistry.

The award from the Physical & Analytical Electrochemistry Division of the Electrochemical Society will be presented at the Pacific Rim International Meeting on Electrochemistry and Solid State Science 2020 meeting held in Honolulu, Hawaii October 4 – October 9, 2020.

This award was established through contributions from ARCO Metals Company and the Aluminum Company of America and recognizes scientists who have made significant scientific contributions to the area of Molten Salts and Ionic Liquids.

Brantley Group Published in JACS

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The Brantley group published their first publication in the Journal of the American Chemical Society (JACS). Their research explores synthesis and reactivity of metallocarbene-containing polymers.

Metallopolymers are an emerging class of materials with potential uses such as semiconductors, catalysts, optical device components, and stimuli responsive networks. While polymer frameworks have been decorated with various organometallic species, the incorporation of metallocarbenes has been largely overlooked. 

Breana Wilson, graduate student in Brantley Lab

“In our article, we report ring opening metathesis polymerization (ROMP) as a strategy for the synthesis of Fischer carbene-containing polymers,” Breana Wilson said. “These polymers could be made with a wide range of molecular weights and exhibited exceptional stability.”

The tungsten carbene subunits could be incorporated into block copolymers, as well as undergo post synthetic modification. Moreover, the metallocarbene polymers were found to release carbon monoxide (CO) upon exposure to light or oxygen.

Wilson said, “These metallocarbene-containing polymers could represent new platforms for the development of functional materials.”

DOI: 10.1021/jacs.9b04077
“Synthesis and Reactivity of Metallocarbene-Containing Polymers”

UT Recognizes ACS for Research Support

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Tom Connelly, current executive director and CEO of the American Chemical Society (ACS), and UT alum Diane Schmidt, former president ACS, visited with faculty, staff, and students from the University of Tennessee’s Department of Chemistry July 17. During their visit, the pair also met with key UT personnel and toured research facilities. Connelly, on behalf of the ACS, was honored for continuing investments in the college.

The American Chemical Society is a pillar of the scientific community and the premiere organization of chemistry advocates in the nation. The ACS maintains that role by bringing together the foremost minds in the field at its nationally recognized conferences, providing vast resources to academic and research-based institutions, and spearheading the industry’s outreach programs. 

Though predominantly US based, the ACS has started to expand its international community building efforts with the formulation of both The Atlantic Basin and Pacific Chem conferences. These international specialty conferences, among other dedicated communication efforts, aim to provide networking opportunities and informational support to individuals from around the world. ACS’s stated mission is “To advance the broader chemistry enterprise and its practitioners for the benefit of Earth and its people.”

“The University of Tennessee is a strong participant in the chemistry enterprise and as such, the university has and continues to enjoy strong ACS support,” Connelly said. “UT regularly maintains representation at the national conferences, contributes and benefits from ACS informational exchange programs, and maintains a strong student chapter.”

Connelly and Schmidt recognized the compelling efforts of both chemistry faculty and their labs. Connelly will report his findings to the ACS board of directors. Future improvements to ACS/UT relations will include improved communications and increased involvement.

“When you receive your degree, they tell you to have all the rights, responsibilities, and privileges conferred by that degree, and I personally feel that one of those rights, responsibilities, and privileges is belonging to the American Chemistry Society,” Schmidt said.

 

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Vogiatzis Group Published in the Journal of Physical Chemistry Letters

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Electronic structure theory describes the motions of electrons in atoms or molecules, and provides a versatile framework for the calculation of molecular geometries, chemical bonding, electronic and spectroscopic properties, reaction barriers, intermolecular interactions, and more. Wave function theory-based methods such as coupled-cluster methods, provide accurate results in a systematic manner, but they typically carry a significant computational cost.

One of the targets of research in Vogiatzis’s group is to accelerate electronic structure theory calculations using machine-learning, which is the field of study that allows computers to learn connections in data without explicit programming.

Machine learning has changed our lives through improved speech recognition, automated vehicle operation, optimized web searching and recommendation, and beyond. Graduate student Jacob Townsend mentions, “Our goal is to take this technology, and allow our calculations to learn from previously executed calculations without introducing any approximations or alchemical approaches. Therefore, the desirable accuracy is reached with significantly less computational effort.”

In their recent publication entitled “Data-Driven Acceleration of the Coupled-Cluster Singles and Doubles Iterative Solver” published in the Journal of Physical Chemistry Letters, the team introduces a novel strategy to accomplish this speedup in a goal to change the way we will execute calculations in the future.

Chemistry Department Hosts 2019 SETCA Meeting

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The theoretical and computational division of the Department of Chemistry hosted the 2019 SETCA (Southeastern Theoretical Chemistry Association) meeting this spring at the University of Tennessee, Knoxville.

The Southeastern Theoretical Chemistry Association (SETCA) is a loose organization of theoretical and computational chemists from across the Southeastern United States. Since its inception in 1970 by Prof. Bruno Linder of Florida State University, its primary function has been an annual conference to give faculty, students, and postdoctoral associates an opportunity to present their most recent research results.

SETCA has a longstanding tradition of excellence in bringing together these communities to address the widespread challenges of computational chemists.

The meeting included a Scientific Programming Workshop, designed for undergraduate research students, conducted by MolSSI, two poster sessions, 12 invited speakers, and a dinner banquet with keynote speaker Weitao Yang.

Congratulations to the six SETCA 2019 Poster Winners!

  • The Quest for a Local Representation of Virtual Spaces for Embedded Wave Functions, Daniel Claudino, Virginia Tech
  • Computational Studies on Substrate Binding Motifs in Dissimilatory Sulfite Reductase, Alexa Griffith, Oak Ridge National Laboratory
  • Modeling of Structural Features in Lignin Based Composite Materials by Hierarchical Decomposition of the Radial Distribution Function, Dayton G. Kizzire, University of Tennessee
  • Approaches for Machine Learning of Ab Initio Intermolecular Properties, Derek P. Metcalf, Georgia Institute of Technology
  • Quantifying Protein Contact Networks through Residue-Residue Pair Interaction Energies, Thomas J. Summers, University of Memphis
  • Data-driven Acceleration of the Coupled-cluster Eigensolver, Jacob Townsend, University of Tennessee

Musfeldt Former Postdoc wins NSF CAREER Award

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Former postdoc, Dipanjan Mazumdar, worked with the Musfeldt group for two years from 2012-2014. He now has a tenure-track job at Southern Illinois University Carbondale and is a 2019 NSF CAREER Award recipient for his work with thermal stability and scaling of nanoscale spin-electronic devices based on novel inverse-Heusler alloys.

“When I started my research career, I learned that one can combine ultrathin layers (nanoscale) of magnetic materials to act as a switch utilizing a subtle quantum physics effect called quantum tunneling,” Mazumdar said. “Essentially, in the classical world when we throw a ball onto a wall, it will always bounce back. Always. In the quantum world, however, there is a small chance that throwing quantum objects such as an electron onto a barrier (wall), the electron will end up on the other side of the barrier.”

Maumdar’s goal of this project is to make faster, smaller, energy-efficient magnetic nanoswitches. 

“Surviving in academia is very difficult. Jan Musfeldt helped my career to stay afloat during a very difficult time,” Mazumdar admits. “So this award (and any award/grant I receive in the future) is always going to be directly or indirectly related to the support I received from her at The University of Tennessee, Knoxville, Department of Chemistry.”