Molecular and Atomic Assembly at Surfaces: Design Strategies to Achieve Chemical Function
Friday, March 31, 12:00 PM, C215 ESC
The central theme of materials science is the dependence of function on structure. The grand challenge is to leverage the composition and structure of a system to develop novel function. In molecular materials, the selection and positioning of specific functional groups will direct packing and stacking, which determine the electronic and chemical properties of molecular thin films and semiconductors. Design of molecular ligands for metal-organic complexation at surfaces can address the long-standing grand challenge of high selectivity in heterogeneous catalysis. Our group is working to develop principles of on-surface molecular self-assembly1 and of metal-organic complexation2 to gain new insight into molecular layers and new chemical activity at metal single-site catalysts.3 This work involves close collaboration with multiple research groups to synergistically combine talent in design, synthesis, sample preparation, characterization, analysis, theory, and computational modeling. Our group uses a range of surface characterization tools to interrogate these systems under well-controlled environments, including scanning probe microscopy, photoelectron spectroscopy, vibrational spectroscopy, and mass spectrometry. We investigate systems under a variety of conditions: solution/solid interface, ultra-high vacuum, and flow reactor conditions at high temperature and high pressure. Here, I will report on recent results in several aspects of this work. We have demonstrated the impact of conformational entropy in impeding self-assembly, but that this can be overcome with appropriate selection of co-solutes. Metal-organic complexes at surfaces can be designed to achieve single-site metal centers in which we can observe redox isomerism, control of metal oxidation state, transmetallation, and chemical spillover to the support. We have transferred this design concept for single-site catalysts to high-surface-area powder oxide supports and shown that these can operate as effective catalysts in solution and under gas flow conditions. Ongoing work will seek to extend understanding of these systems to achieve molecular thin films and single-site catalysts of greater complexity.
Steven L. Tait is Professor and Department Chair in the Department of Chemistry and Adjunct Professor in the Department of Physics. He also serves as Associate Director of the IU Electron Microscopy Center. Prof. Tait’s research group studies surface science and catalysis, especially for the development of single atom catalysts that are capable of reducing global energy demands through efficient chemical transformations of essential chemical products. Their work combines aspects of physical and materials chemistry with advanced spectroscopy and microscopy characterization tools. Prof. Tait teaches courses in general chemistry, physical chemistry, and surface chemistry and is the recipient of the 2022 James P. Holland and Morley Award for Exemplary Teaching and Service in the College of Arts and Sciences. Steve is a fellow of the American Vacuum Society and an active member of the American Chemical Society, where he has served on several national committees. Steve is an active member of the Diversity Affairs Committee in the Department of Chemistry.
Community Testing with Quiet Supersonic Aircraft
Langley Research Center
Friday, April 7, 12:00 PM, C215 ESC
Continued interest in flying faster than the speed of sound has led researchers to develop tools and technologies for new generations of supersonic aircraft. One important aspect of these designs is that the sonic boom noise (“sonic thump”) will be significantly reduced as compared to that of previous planes, such as the Concorde. Currently, U.S. and international regulations prohibit civil supersonic flight over land due to people’s annoyance with the impulsive sound of sonic booms. In order for regulators to consider lifting the ban and introducing a new rule for supersonic flight, surveys of the public’s reactions to the new sonic thump noise are required. To conduct these community overflight studies, NASA is building the X-59, a quiet supersonic demonstration research aircraft. This presentation will discuss NASA’s role in providing data to international regulators and the status of its preparations for community testing.
This in-person colloquium will also be broadcast: https://byu.zoom.us/j/92289808080
Alexandra Loubeau is a Research Aerospace Engineer at NASA Langley Research Center in Hampton, VA. She received her M.S. and Ph.D. in Acoustics from Penn State and has been researching sonic boom acoustics since then. As a team co-lead for sonic boom community testing research at NASA, she is involved in the planning, execution, and analysis of experimental, modeling, and psychoacoustics research. Alexandra enjoys playing the violin in a local orchestra, swimming, and learning languages.
Cleaner than a Cleanroom: Filling Technology Gaps for Space Telescopes and LIGO - First Contact Polymers as a Path Towards Atomic Cleanliness
James P. Hamilton
University of Wisconsin Platteville
Friday, April 14, 12:00 PM, C215 ESC
Creating and maintaining unprecedented cleanliness levels has become a limiting technological requirement for projects like LIGO and future starshade technology for NASA’s Great Observatories of the future. Over the last 20 years, we have developed a family of peelable residue-free, non-tearing polymer coatings that safely clean and protect surfaces. These Apply-Dry-Peel coatings begin to fill the technology gap that exists in a) trying to clean historically uncleanable nanostructured and coated surfaces as well as in b) meeting the zero dust tolerance requirements of high energy laser optics and some semiconductor processes. This family of First Contact Polymers (FCPs) was a critical, enabling technology in LIGO’s gravitational wave discoveries of 2015, NASA’s Starshades and can greatly extend the lifetime of current mirror coatings on large astronomical mirrors such as the 10meter class mirrors at the Keck Observatory and GTC in the Canary Islands. This presentation will present selected research results in support of such physics projects worldwide.
Our novel, residueless polymeric stripcoatings are applied as a liquid and subsequently peeled off the substrate as a solid, strong, non-tearing film. These novel polymer blend stripcoatings safely clean and protect a wide variety of nanostructured surfaces and leave the surface almost atomically clean and “space ready.” Contaminant removal was monitored by various techniques, including Nomarski Microscopy, BRDF, Atomic Force and Scanning Electron Microscopy, and XPS and Auger spectroscopy. High power laser damage (LIDT) testing results also demonstrate YAG laser damage thresholds on new YAG laser optics of 3 J/cm2 before AND after cleaning, clearly demonstrating no residue. Finally, the use of FCP on high-power laser optics resulted in an absorption coefficient decrease of 24.3% after cleaning, and the authors claimed that the absence of residue makes the FCP conducive to the long-term preservation of optical components. In addition, data demonstrates that the material safely removes particulate contamination and finger oils from microstructures such as the 300nm wide lines on diffraction gratings and similar submicron features on Si wafers and is an excellent nano replicator. Another application of the polymer film is as a sample matrix for beamline studies. Use as a dry powder and biological sample support in beamline samples and for spectroscopy and time-resolved photoluminescence of nanowires has been demonstrated. Other applications in the literature include a) transfer patterned nanoparticle arrays red to a flexible polymer surface, b) use of a droplet as a spherical microcavity-based membrane-free Fizeau interferometric acoustic sensor, c) as an SEM-EDS sample matrix for embedded moon dust analysis, and d) for CCD and sensor cleaning.
This in-person colloquium will also be broadcast: https://byu.zoom.us/j/92289808080
As a Wisconsin Distinguished Professor, James P. Hamilton founded two companies, is the Director of the UW System NCCRD Nano Research Center, and is in the Chemistry department at the University of Wisconsin-Platteville in the USA. His research on precision contamination control in aerospace, photonic and astronomical optics has brought him to the summits of most of the large telescope sites in the world, including Hawaii, the Canary Islands, and China. Recent efforts for NASA on an $875k research contract have also led to new planetary protection research involving deep space sample return missions and telescopes. Following a B.A. and graduate work at the University of Maine-Orono in Natural Products, Inorganic Chemistry, and Surface Science, he completed a Ph.D. at UW-Madison in physical & analytical chemistry specializing in atomic, molecular and optical physics. His research specializes in nanocomposite materials instrumentation development, nanoparticle thermodynamics, and laser spectroscopy. Lecturing on research and collaborating all over the world, he also raised $4.3 million in investment funds for his companies, Xolve, Inc. and Photonic Cleaning Technologies, the manufacturer of First Contact Polymers, which has sales in 77 countries. He is a senior member of the American Physical Society and SPIE-The International Society for Optical Engineering, as well as the AIAA (American Institute of Aeronautics and Astronautics). He also is a member of the American Chemical Society, Sigma Xi, the Coblenz Society, and Sigma Pi Sigma (Honorary Physics Society). He also serves on the AIAA Space Settlement Technical Committee and as a coordinator and session chair for conferences like SPIE Optics and Photonics. He enjoys scuba diving, sailing, skiing, hiking, and fly fishing. Conversant in French and functional in German, he enjoys traveling and learning about new languages and cultures. He was also recently selected as 2022-2024 Distinguished Lecturer for Sigma Xi, the international research honor society.
Friday, September 8, 12:00 PM, C215 ESC
Andrew J. Sampson
UT San Antonio
Friday, October 6, 12:00 PM, C215 ESC
Sandia National Lab
Friday, December 1, 12:00 PM, C215 ESC
We welcome anyone who wish to attend, and typically serve refreshments ten minutes before the colloquium begins. Speakers generally keep their presentation accessible to undergraduate physics students.