Newswise — Three researchers from the U.S. Department of Energy’s (DOE) Argonne National Laboratory have been inducted into the 2023 class of Fellows of the American Physical Society (APS). This prestigious honor signifies recognition and esteem by a scientist’s professional peers and is only awarded to less than one-half of one percent of the APS membership each year. Founded over 120 years ago, the APS represents over 50,000 members worldwide and supports the advancement and diffusion of the knowledge of physics for the benefit of humanity.
This year, Argonne’s newest APS Fellows are materials scientist Dillon Fong, cosmologist Katrin Heitmann and theoretical chemist Ahren Jasper.
Fong’s research involves the use of X-rays to probe thin films and other related materials. He uses the X-rays from Argonne’s Advanced Photon Source, a DOE Office of Science user facility, and other synchrotrons to investigate the atomic structures of materials as they change: for example, as they collect to form a new material or as they evolve in different environments. This "X-ray vision" is essential for the discovery and development of novel low-power microelectronics, systems for neuromorphic computing that acts similarly to the human brain, and superconductors that offer no resistance to the movement of electrons at relatively high temperatures.
Fong has worked on the design and construction of systems for the growth of oxide thin films on substrates, using many techniques that were among the first of their kind at a synchrotron. These films are only nanometers thick.
“This recognition is especially meaningful to me because it is from the American Physical Society, an organization that not only promotes science but works to have an impact on society,” Fong said. “It is an acknowledgement to the contributions I have made in collaboration with many outstanding scientists, including other members and Fellows of the American Physical Society.”
Katrin Heitmann is the deputy director of Argonne’s High Energy Physics division, a physicist and computational scientist. She is also a senior associate for the Kavli Institute for Cosmological Physics at the University of Chicago and a member of the Northwestern-Argonne Institute of Science and Engineering at Northwestern University.
Heitmann’s research currently focuses on computational cosmology, in particular, on trying to understand the causes for the accelerated expansion of the Universe, and the role of dark matter and dark energy. She is responsible for large simulation campaigns with the Hardware/Hybrid Accelerated Cosmology Code (HACC) and for the tools in the associated analysis library, CosmoTools. Heitmann is a member of several major astrophysical surveys that aim to shed light on this question and was until recently the spokesperson for the Dark Energy Science Collaboration for the Rubin Observatory Legacy Survey of Space and Time.
“I have spent my career making contributions to a range of different scientific communities whose discoveries have helped us understand our universe a little bit better,” Heitmann said. “It is a big honor to be inducted as a Fellow into this society, which is made up of world-leading researchers whose collaborations have created new knowledge and enriched our lives.”
Ahren Jasper is a theoretical chemist in the Gas Phase Chemical Dynamics Group at Argonne. He studies chemical reactions that result from the competition of a variety of underlying microscopic processes. Complex gas phase environments — from combustion engines to the atmosphere — involve a large number of elementary reactions in competition with one another. Hundreds or even thousands of reactions can conspire together to control important global properties like heat release and pollutant formation. Furthermore, each reaction is often a sensitive function of both temperature and pressure. To provide the vast amounts of data required to build detailed and predictive models, scientists have increasingly turned to theory.
Jasper has contributed new theories and codes for describing both pressure-dependent and multistate chemistry. In these two types of chemical reactions, the development of first-principles approaches has lagged behind the development of theories for more conventional reactions. First-principles calculations are used to understand and predict the properties of materials and molecules from basic physical principles, without relying on experimental data or models based on such data.
Jasper’s methods emphasize details about how vibrational energy and angular momentum are transferred during collisions that occur in gases. Jasper’s semiclassical approaches combine classical nuclear motion with quantum mechanical models for the electronic variables. They provide a useful balance of computational affordability and accuracy.
“It’s very encouraging to get recognition from this prestigious society because it helps to show the importance of advancing the accuracy and broadening the applicability of these kinds of theories and codes,” Jasper said. “Many of the great chemical physicists I look up to are already Fellows of the APS, and I am excited to be honored in joining them.”
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