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January 17, 2008
Research at the interface of chemistry and physics
WEST LAFAYETTE, Ind. — When most of us think of physics, we think of pulleys, atoms, or quarks. When we think of chemistry, our thoughts turn to explosions, synthesis, or catalysts. However, these seemingly disparate worlds have a strong interface known either as physical chemistry or chemical physics, in which the tools and approaches of physics are brought to bear on problems of chemical interest. This interdisciplinary field has a rich tradition, but also continues to develop and evolve as physical chemistry approaches are applied to an ever-widening array of problems.
In a recent physics colloquium, Professor Timothy Zwier, M. G. Mellon Distinguished Professor of Chemistry and head of the Department of Chemistry, spoke to the physics audience about his physical chemistry research group’s studies in laser spectroscopy and chemical dynamics.
Ian Shipsey, Julian Schwinger Distinguished Professor of Physics, coordinates the regular colloquium series hosted by the department of physics. A forum where experts talk about their work, the colloquia are “a central part of the intellectual life of the physics department.” Shipsey invited Zwier to speak because he is a physical chemist applying one of the most important tools of physics, lasers, to studies of large, flexible molecules.
To a mix of graduate physics and chemistry students and professors on January 17, Zwier presented a talk entitled, “Laser spectroscopy and dynamics in the complexity gap.” The audience was introduced to research his team is currently conducting using laser spectroscopy.
Zwier described the ‘complexity gap’ that exists between small molecules containing just a few atoms and large macromolecules such as proteins. In small molecules, the atoms chemically bind to form a single molecular shape; while in proteins, the various parts of the molecule can twist and turn relative to one another to form a huge number of different shapes, called molecular conformations.
He also described studies of molecules containing up to 50 atoms in which hundreds or thousands of conformational minima are possible. By cooling these molecules in a gas phase expansion to very low temperatures, his group is able to use tunable laser radiation to interrogate the molecules, thereby determining their preferred shapes. These spectroscopic studies are then followed by studies of the dynamics of conformational isomerization, in which lasers are used to initiate shape changes and measure the energy required to do so.
One thing Zwier hoped the audience would take from his presentation was “an appreciation for the laser-based tools used to understand why molecules take on the shapes they do and how they are transformed from one shape to another.”
According to Zwier, a healthy interaction between researchers in chemistry and physics is key to future discoveries in this fascinating interdisciplinary field. Several of the faculty in chemistry and physics are currently actively engaged in discussions about ways to further strengthen the interactions between them. They hope ultimately to establish stronger formal links between the two departments, and draw students with strong aptitudes in both fields into physical chemistry/chemical physics programs here at Purdue.
Shipsey hoped that the audience would walk away with “an appreciation for Zwier’s beautiful science.”
Zwier won the Earle K. Plyler Prize for Molecular Spectrometry from the American Physical Society in 2007 and is one of the Senior Editors for the Journal of Physical Chemistry.
Writer: Karen Pulliam, (765) 494-1764
kp@purdue.eduSources: Tim Zwier, head of the Department of Chemistry, and
M. G. Mellon Distinguished Professor of Chemistry—Physical Chemistry
(765) 494-5278, zwier@purdue.edu
Ian Shipsey, Julian Schwinger Distinguished Professor of Physics
(765) 494-5049, shipsey@physics.purdue.edu