Thursday, Sept. 5, 3:30pm - 4:30pm, NHB 1.720
David Mulvane Ehrsam and Edward Curtis Franklin Professor of Chemistry
Two dimensional infrared (2D IR) spectroscopy is used to investigate the dynamics of water. It is shown that a probe molecule, methylthiocyanate (MSCN), can be used to measure water hydrogen bond dynamics. The efficacy of this molecule is the CN stretch’s ~30 ps lifetime, making possible measurements of relatively slow processes. In addition, MSCN has a well-defined spectrum even in concentrated HCl solutions. First, MSCN is used to investigate dynamics of concentrated LiCl solutions. Chemical exchange is observed that reveals the dynamics of the interchange of water and Li+ bonding to the CN nitrogen lone pair. The time constants for Li+ replacing water and water replacing Li+ are obtained. Then, concentrated HCl solutions are investigated. The CN spectrum shows two bands, one with water H-bonded to the N lone pair and one with hydronium bonded to the lone pair. Again chemical exchange is observed, and the time constants for exchange of hydronium to water and vice versa are presented as a function of HCl concentration. Two possible mechanism can describe the data: 1. the physical exchange of hydronium and water, as occurs for Li+ and water, and 2. proton hopping between hydronium and water, in which case only a proton moves. Ab initio molecular dynamics simulations are used to determine the mechanism and other important aspects of the observables. It is found that 80% of the observed dynamics are from proton hopping. From the HCl concentration dependence in the experiments and the simulations it is possible extend the high HCl concentration measurements to the limit of infinite dilution to obtain the proton hopping rate. The measurement of the hopping rate determined from the direct chemical exchange experiments taken to infinite dilution coincides with the value inferred from mobility measurements. An important result is that the hopping time is the same as the hydrogen bond rearrangement time in pure water. It is argued that proton hopping is triggered by the concerted hydrogen bond rearrangement of many water molecule as obtained from 2D IR spectral diffusion measurements of pure water. The water hydrogen bond rearrangement as the driving force for proton hopping is affirmed by the temperature dependence of pure water spectral diffusion compared to the temperature dependence of proton hopping times from mobility measurements.
h-index: 81 Total Publications: 443 Total Citations: 22,580 (Web of Science, Jul. 2019)
Thursday, Aug. 22, 3:30pm - 4:30pm, NHB 1.720
Assistant Professor of Chemistry
Research in our group is inherently multidisciplinary; we combine tools from chemistry, optics, biology, and microscopy to develop new approaches to probe dynamics. We study dynamics in two classes of systems: biological and bio-inspired light-harvesting systems that are of interest to solar energy research and biomass production; and bacterial and mammalian receptor proteins that are targets for human therapeutics. To explore these systems, we use ultrafast transient absorption spectroscopy, single-molecule fluorescence spectroscopy, and develop model membrane systems.
h-index: 16 Total Publications: 25 Total Citations: 1208 (Web of Science, Jul. 2019)
h-index: 17 Total Citations: 1628 (Google Scholar Citations, Jul. 2019)
Monday, May 13, 3:30-4:30pm, WEL 2.122
Washington State University
The core instruments designed and constructed in the Clowers Research Group are focused almost exclusively on the accurate measurement of gas-phase ion properties. While stand alone ion mobility instruments are extremely useful in a field-based setting the combination of this technique with mass spectrometry provides a second dimension of analysis that is extremely powerful. The research ion mobility instruments being constructed in our laboratory include both high (760 Torr) and low pressure (~4 Torr) instruments both capable of operating at a range of temperatures.
h-index: 25 Total Articles: 68 Total Citations: 2261 (Web of Science, Apr. 2019)
h-index: 30 Total Citations: 3330 (Google Scholar Citations, Apr. 2019)
Thursday, April 25, 3:30-5:00pm, WEL 2.122
Arizona State University
At the single molecule level, experiments now follow the steps in the life's journey of a single protein; from its synthesis in a ribosome, to its activity in a complex dynamical environment, to its death by proteolysis. At the cellular level, experiments reveal with incredible detail how groups of proteins come together to regulate important events such as cell division. In an ideal world, experiments should not require much modeling to reveal physical insight -- the data should be self-evident. Yet biophysical data is noisy, complex and largely incomplete for a variety of reasons. This is especially true of data collected from live cells. On the theory side, we develop, adapt and use tools derived from statistics, statistical physics and stochastic processes, broadly defined, to understand living systems across multiple time and length scales. On this front, there are two main research directions in our group: 1) we develop methods to infer models from imaging and spectroscopy data in biophysics with a recent focus on Bayesian nonparametrics; 2) we are developing models to understand enzymatic and molecular motor efficiency. On the experimental front, we are exploring the role of hydrodynamics on the interaction of bacterial predators with their prey.
h-index: 12 Total Articles: 36 Total Citations: 614 (Web of Science, Apr. 2019)
h-index: 16 Total Citations: 928 (Google Scholar Citations, Apr. 2019)
Thursday, April 11, 3:30-4:30pm, WEL 2.122
Crown Family Professor of Molecular Engineering
University of Chicago
We are interested in the structure and dynamics of condensed phase systems, and in particular, in the theory of time-dependent phenomena in liquids. Experimentally, one important approach for determining the structure and dynamics of condensed matter involves linear and non-linear vibrational spectroscopy. Typically, such spectroscopy contains information about local molecular environments, whose extraction, however, usually requires theoretical models and their solutions. In order to accomplish this, we use ab initio calculations, molecular dynamics simulations, statistical mechanics, and basically any theoretical approach that will enable us to further our understanding. The systems we are working on include water, peptides and proteins, interfaces, membranes etc.
h-index: 66 Total Articles: 209 Total Citations: 12,746 (Web of Science, Mar. 2019)
h-index: 74 Total Citations: 15,714 (Google Scholar Citations, Mar. 2019)
Wed. April 10, 11am-12noon, NHB 1.720
h-index: 32 Total Citations: 4829 (Google Scholar Citations, Mar. 2019)
Co-presented with the Dept. of Chemical Engineering
Thursday, March 28, 3:30-4:30pm, WEL 2.122
Texas A&M University
Our research considers fundamental questions of optical energy conversion relating to plasmonic and inorganic nanoscale materials. Our experiments are principally designed to identify and optimize unique nanoscale phenomena useful for solar energy conversion, as well as related opportunities at the intersection of nanophotonics and chemistry for broad application beyond the scope of solar energy. The current world record solar cell operates at 44.4% power conversion efficiency. Thermodynamic analyses indicate that much higher efficiency is theoretically possible. Indeed, technical challenges, rather than laws of nature, limit current solar power convertors from achieving the maximum thermodynamic efficiency of 95%.
h-index: 10 Total Articles: 18 Total Citations: 871 (Web of Science, Mar. 2019)
Thursday, March 14, 3:30-4:30pm, WEL 2.122
Associate Professor, Mechanical Engineering
The unique physics of fluids at the microscale holds both challenges in the understating of basic physical phenomena and opportunities in leveraging these phenomena toward new technologies. Our lab combines experimental, analytical, and computational tools to study microfluidic problems characterized by coupling between fluid mechanics, heat transfer, electric fields, chemical reactions, and biological processes. We are currently interested in understanding basic mechanisms in electro-viscous-elastic interactions, thermocapillary, superhydrophobic surfaces, and in utilizing them to create new technologies for flow patterning, configurable microstructures, 3D printing, biosensing, and single cell analysis.
h-index: 15 Total Articles: 46 Total Citations: 839 (Web of Science, Mar. 2019)
Thursday, February 28, 3:30-5:00pm, WEL 2.122
Montana State University
Our research group utilizes nonlinear microscopy and ultrafast laser spectroscopy to interrogate and understand the optical, electronic, and chemical properties of materials important for advanced solar energy, catalytic, and electronics technologies. We are particularly interested in correlating macroscopic functionality with structural and compositional information on length scales between 10 nanometers and 10 microns. To this end, we use a variety of nonlinear microscopies, ab initio and semi-empirical theoretical methods, and ongoing technique development to advance understanding of how atomic and molecular scale interactions couple with mesoscopic interfaces and defects to determine overall material and device properties.
h-index: 14 Total Articles: 28 Total Citations: 597 (Web of Science, Feb. 2019)
Thursday, February 21, 3:30-4:30pm, WEL 2.122
Professor ; Chair
University of Puget Sound
Dan is interested in environmental analyses and monitoring of air and water. Projects with Puget Sound students have included remote sensing measurements of in-use emissions from vehicles such as cars, trucks, school buses, transit buses, trains, and boats (small personal vessels, commercial vessels and ocean-going vessels) both in the U.S. and internationally. Water analyses include quantifying trace levels of pharmaceuticals and illicit drugs in wastewater.
h-index: 9 Total Articles: 16 Total Citations: 228 (Web of Science, Jan. 2019)
h-index: 10 Total Citations: 388 (Google Scholar Citations, Jan. 2019)
Thursday, February 7, 3:30-4:30pm, WEL 2.122
Marguerite Blake Wilbur Professor in Natural Science
For summaries of the many research topics of the Zare Lab, see the ZareLab Guide.
h-index: 111 Total Articles: 817 Total Citations: 49,142 (Web of Science, Jan. 2019)
Thursday, January 31, 3:30-5:00pm, WEL 2.122
George L. Argyros Professor of Chemistry
Our research spans from single materials to fully integrated, operational devices and focuses on solving present-day issues in energy and chemical sensing by controlling interactions between light, semiconductors, catalysts, and liquids.
h-index: 86 Total Articles: 409 Total Citations: 36,577 (Web of Science, Jan. 2019)
Faculty Recruiting Seminar
Wednesday, January 16, 3:30-4:30pm, WEL 2.122
PhD 2016, Arizona State University
The Xu group is an interdisciplinary lab that develops new physicochemical tools to interrogate biological, chemical, and materials systems at the nanoscale with extraordinary resolution, sensitivity, and functionality. To do so, we take a multidimensional approach that integrates advanced microscopy, spectroscopy, cell biology, and nanotechnology.
h-index: 8 Total Citations: 265 (Google Scholar Citations, Dec. 2018)
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