Annenberg Learner Courses
Hosted by Wilton L. Virgo
Light a match and chemical change happens in a one-way process: Reactants are transformed into products. But there are many chemical reactions called "equilibrium reactions" that operate in both directions: with reactants and products always present. The Unit 9 video will show how chemical equilibrium works, the essential role it plays in the function of the human body, and how it is exploited in chemical processes such as ammonia synthesis, a process that provides food for up to half the world's population.
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Hosted by Wilton L. Virgo
From an instantaneous explosion to the slow rusting of iron, the rates at which different chemical reactions proceed can vary tremendously depending on several factors, including temperature and concentration. Sometimes, like with the rotting of food, chemists want to slow down reaction rates. But often, the goal is to speed them up—and one way to do this is to use a catalyst. In this video, we will learn about catalysts and how using them can lead to cheaper, more effective, and more sustainable drug production processes. We will also discover how the rates of some reactions, like nuclear decay, are unchangeable, and how scientists take advantage of this, using PET scans to reveal the presence of disease.
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Wilton L. Virgo is a quantum physical chemist with expertise in performing state-of-the-art research in laser spectroscopy and publishing cutting-edge scientific articles. As a Research Affiliate in the Department of Chemistry at MIT, he uses technology-driven global knowledge systems to collaborate and exchange ideas that solve problems related to climate change at the microscopic level.
Dr. Virgo earned his AB in 2000 from Princeton University and his PhD in 2005 from Arizona State University, both degrees in Physical Chemistry. He has performed research in laser spectroscopy at Princeton University, Brookhaven National Laboratory, Arizona State University, and Wellesley College, where he worked with student assistants using lasers to drive reactions involving organic molecules in solution; the application of this would be development of a molecular detector for use in early cancer detection.
Haslam and Dewey Professor Robert W. Field of the Department of Chemistry was Dr. Virgo's host at MIT. As an MLK Visiting Scholar and postdoctoral associate in Prof. Field's laboratory, Dr. Virgo focused on investigating how metastable molecules are involved in both intra-molecular and intermolecular energy flow and on inventing new, sophisticated techniques using lasers, molecular beams and detection of the metastables on metal surfaces.
- American Journal of Physics
- November 19, 2013
A quantum model for calculating the combined Stark and Zeeman effects of simultaneously applied electric and magnetic fields is presented. Our focus here is on atoms with hyperfine structure, such as Cesium. Matrix representations of the Stark, Zeeman, and hyperfine interaction operators are constructed using angular momentum theory and spherical tensor algebra. Matrix elements are evaluated in order to determine the energy-level dependence on the applied fields and reveal intriguing state dynamics in both parallel and orthogonal electric and magnetic fields. The fundamental physics is relevant for an advanced undergraduate or graduate quantum mechanics course.
- Cambridge, MA
- September 20, 2012
Quantum mechanics is the mathematical foundation for chemistry and physics on the microscopic scale. The energies and interactions between atoms and molecules can be described using the mathematics of matrices and quantized angular momentum. The seemingly esoteric mathematical language and quantum behavior of atoms and molecules have directly led to modern technology such as compact fluorescent bulbs, lasers, global positioning system (GPS) and magnetic resonance imaging (MRI). Quantum Mechanics in Everyday Life provides an introduction to the language of quantum and leads the reader to a deeper understanding of familiar, widely-used technology at the atomic and molecular level.
- J. Phys. Chem. A., Feature Article
We review recent research on the acetylene S1 state that illustrates how mechanistic rather than phenomenological information about Inter-System Crossing (ISC) may be obtained directly from frequency-domain spectra. The focus is on the dynamically rich "doorway-mediated" ISC domain that lies between isolated spectroscopic spin-orbit perturbations and statistical-limit interactions between one singlet "bright state" and a quasi-continuum of triplet "dark states". New and improved experimental and data processing techniques permit the statistical-model curtain to be drawn back to reveal mechanistically-explicit pathways, via one or more identiﬁable, hence manipulable, doorway states, between a user-selected bright state and the undifferentiated bath of dark states.