Venkat Viswanathan was featured in MIT News for his research in battery technologies. In collaboration with researchers from MIT, Viswanathan is studying a new kind of electrolyte for "self-healing" lithium battery cells, which could lead to longer driving range, lower cost electric vehicle batteries.
In the news
Quantum effect could explain how chiral molecules interact: Electron spin polarization promotes recognition between molecules of similar chirality.
Biomolecules from small amino acids to large DNA helices are chiral, and how they interact depends on their chirality. A newly identified quantum effect could help explain how biomolecules’ chirality persists. When two molecules interact, their electron clouds reorganize. In chiral molecules, that reorganization is accompanied by electron spin polarization that enables molecules of the same chirality to interact more strongly than molecules of opposite chirality, reports a research team led by Ron Naaman and Jan M. L. Martin of the Weizmann Institute of Science and David H. Waldeck of the University of Pittsburgh (Proc. Natl. Acad. Sci. USA 2017).
“The mechanism that they have demonstrated is different from any that was previously reported,” comments David N. Beratan of Duke University. “If the idea holds up, it could entirely change the way we think about molecular recognition in biological and organic chemistry.”
The Office of Naval Research has announced awards of $16 million through its 2017 Young Investigator Program (YIP). The awards were made to 33 scientists whose research holds strong promise across several naval-relevant science and technology areas.
Sergey Frolov was among this year's Young Investigator Award recipients for his proposal "Semiconductor Nanowire-Based Quantum Emulators".
Established in 1998 with a gift from Dietrich School alumnus, David Bellet (A&S '67) and his wife Tina, and endowed in 2008 through the family's further generosity, this annual award recognizes outstanding and innovative teaching in undergraduate studies in the Kenneth P. Dietrich School of Arts and Sciences.
Sean Garrett-Roe has been selected to receive a 2017 Chancellor's Distinguished Teaching Award. The Chancellor's Distinguished Teaching Award recognizes teaching excellence by members of the University of Pittsburgh's faculty. This award consists of a cash prize to the faculty member and a grant to support the faculty member's teaching activities.
Garrett-Roe was recognized for his work with the Process Oriented Guided Inquiry Learning (POGIL) approach, which uses a flipped classroom model, multisensory input and incorporates technologies to encourage students to engage, derive and interpret the materials of physical chemistry. He has also shared his pedagogical models in such venues as Pitt’s Summer Instructional Design Institute and the American Chemical Society’s national meeting.
Photovoltaics in action: Electron motion in a type-II InSe/GaAs semiconductor heterostructure has been recorded in a movie immediately after photoexcitation with high spatial and temporal resolution.
Electrons are the lifeblood of semiconductor devices, from transistors that power computers and smart phones, and semiconductor diodes that light up the night, to photovoltaic cells that harvest solar energy to power it all. Under the influence of applied voltages or light stimulations, electrons flow through nanoscale channels and plummet potential gradients at interfaces of disparate materials. In a semiconductor device this ebb and flow occurs several times every nanosecond within billions of transistors on a single microchip, unseen by human eye, but creating text, images and movies in strings of 0s and 1s. But the true time and spatial scales on which electrons are energized and transported span a range of hundreds of femtoseconds and tens of nanometres. Thus, to capture in a movie the physical phenomena of electrons in a device requires a truly extraordinary camera. Writing in Nature Nanotechnology, Man et al. report an experiment that performs just that. Specifically, they record a movie of electron flow in energy, space and time within a semiconductor heterojunction composed of GaAs in physical contact with InSe by imaging electrons emitted into vacuum through the joint action of femtosecond duration IR generation and UV electron emission laser pulses.
Matter-Light Condensates Reach Thermal Equilibrium
Making use of improved microcavities, hybrid condensates of matter and light can be tuned to reach a thermal equilibrium state, despite their finite lifetime.
In a laser, coherent light is created by stimulated emission of photons from an “inverted” state of matter that is significantly out of thermal equilibrium. “Inverted” means that excited states of the matter are more occupied than lower energy states, so that emission is more likely than absorption. The coherence of laser light is closely related to a quite different, and less commonly encountered, state of matter—a Bose-Einstein condensate (BEC). In the textbook description of a BEC, at low enough temperatures or high enough densities, a large number of particles occupy the same state, producing a coherent state of matter. In contrast to laser light, the textbook BEC is in thermal equilibrium. Condensates of polaritons—half-light, half-matter quasiparticles—have so far been found in conditions halfway between those of an equilibrium BEC and those of a laser. Work by David Snoke and colleagues now shows that such polariton condensates can be tuned to reach a thermal equilibrium state. With this tunability between an equilibrium and nonequilibrium state, researchers can explore how the character of phase transitions evolves between the two limits.
Sara Majetich has been named an IEEE Fellow. Majetich is being recognized for her contributions to the understanding of magnetic nanoparticles. She studies the fundamental physics of magnetic nanoparticles that have very uniform sizes and applies her work to the design of functional materials that have applications in data storage media, high-speed electronics and biomedicine.
Fellowship is the highest grade of membership in IEEE, and is considered to be a prestigious honor among the technical community. Fellowship is conferred by the IEEE Board of Directors on only one-tenth of one percent of the total voting membership of the organization each year. The distinction recognizes outstanding accomplishments in any of the IEEE’s fields of interest, which focus on advancing technology for the benefit of humanity.
The IEEE is the world’s leading professional association for advancing technology for humanity. Through its more than 400,000 members in 160 countries, the association is a leading authority on a wide variety of areas ranging from aerospace systems, computers and telecommunications to biomedical engineering, electric power and consumer electronics.
The American Physical Society (APS) has elected Judith Yang to the position of Fellow. APS President Homer Neal cited Yang’s selection: “For seminal contributions to in situ environmental transmission electron microscopy, the fundamental understanding of metal oxidation and the application of nanomaterials and catalysis.” Yang joined 14 other members of the APS Division of Materials Physics to be named Fellows this year. The APS caps the number of new Fellows elected each year to one half of one percent of its 51,000 members internationally. The Fellowship committee evaluates each nomination based on a criteria of exceptional contributions to the physics enterprise, including outstanding research, application, leadership or service and contributions to education related to the field of physics.
“I feel honored in becoming a Fellow of the American Physical Society, but I also look forward to the attention and recognition it will bring to the University of Pittsburgh,” said Yang. “We have only recently been able to see the dynamic processes of oxidation at the nanoscale by using environmental transmission electron microscopy; we are starting to gain a new fundamental understanding of oxidation that challenges classical theories.
David Waldeck is one of this years recipients of the Women Chemists Committee Award for Encouraging Women into the Chemical Sciences. This award recognizes significant accomplishments by individuals, male or female, who have stimulated or fostered the interest of women in chemistry, promoting their professional developments as chemists or chemical engineers.
The mission of the Greater Pittsburgh Area Women Chemists Committee (WCC) is to be leaders in attracting, developing and promoting women in the chemical sciences.