As far as Professor Crim and his lab are concerned, there are only a handful of attractive molecules. They buy them by the “mole” from businesses like Aldrich Chemical, which traffic in tens of thousands of distinct molecules.

A mole, like a “dozen,” is a very specific number of molecules, only much larger, 6 x 1023 to be exact. And the volume of a mole depends upon the substance. A mole of air molecules for example is about the size of a bread box. A mole of water is a fraction of a Dixie cup.

This week’s Tuesday Town Talk will be given by a renowned physical chemist, F. Fleming Crim, a John E. Willard and Hilldale Professor of Chemistry Professor at the University of Wisconsin, entitled “Good Vibrations: Using lasers to direct chemical reactions.” It will be held August 5th, 6:00 – 7:15 pm at the Wilkinson Public Library in the Program Room. A $5 donation is welcomed.

Crim has learned how to control the vibration of the molecules he purchases (or occasionally makes), using lasers, a technology which has transformed the world’s understanding of chemistry and the practice of chemistry itself. Crim will describe how vibrations control chemical reactions and why it is important to understand how molecules vibrate.

Overall, physical chemists want to know the fundamentals of how molecules behave and likewise Crim is interested in the pure academic pursuit of trying to better understand how the world works.

“I study the physics of molecular reactions, simple motions we can understand, like the vibrations of molecules,” he says. “We can take our intuitive understanding of classical systems, like balls rolling down hills, or kids in a skate park, to understand some of the workings of molecules.”

He asks questions like, What motion carries atoms across a barrier? “To get a picture of this, you can think about climbing a mountain,” he says. “There is a minimum altitude one must climb to get over a mountain. But you must walk in the right direction. The same thing describes chemical reactions. In other words, there is a ‘critical configuration.’”

“Scientists have ‘pictures’ of how molecules behave,” continues Crim. “These pictures are mental constructs or models. We don’t have movies of molecules vibrating, but the more detailed we can go experimentally the more we can test our models. We want to know if the experimental results fit into our ‘picture’ of how chemistry happens.”

His chief interest is to understand how chemical reactions occur. As simple as the problem sounds, his research in chemical dynamics is complex. He studies the fundamental details of chemical reactions in gases and liquids by creating highly energized molecules and following their behavior.

He uses three basic steps in his research. Using specific “preparation” techniques, he makes molecules vibrate, then sends in a reactive atom, and finally tries to detect the products of that reaction.

Lasers help steer specific chemical reactions. “The interactions of molecules and light are very specific. Scientists can’t control molecules with a pair of tweezers (although some people are coming close), so we use lasers. Lasers spit out a very narrow range of color (wave lengths), and short pulses (every 10 nanoseconds – one ten billionth of a second) which we use to our advantage.”

The importance of understanding chemistry generally cannot be overestimated. “The late Richard Feynman once said,” Crim recalls, “that if there were a cataclysmic event, and he could only pass on one piece of knowledge to future generations, it should be the atomic hypothesis – that everything is made of atoms, everything is atomic in structure.”

Chemistry can be described simply as molecules losing atoms or gaining atoms. They break bonds and make bonds. One rearrangement can make a huge difference in how a substance behaves.

Crim finds beauty in chemistry’s understanding of this behavior: “The beauty of chemistry, first of all, is that simple ideas explain complex phenomena. And secondly, that we can build models that are quantitatively predictive. And we can use a few organizing principles, like the conservation of energy and the conservation of momentum, to describe phenomena like, why salt melts ice in the road, why the sky is blue, and why water expands when it freezes. We chemists are attracted to this simplicity.”

Crim is in town for a week, participating in a Telluride Science Research Center workshop, along with 25 other scientists, to talk about how molecules vibrate. “TSRC gathers real experts in highly specialized fields,” he says, “which makes a confluence of ideas a possibility and can trigger new work. We have an opportunity to examine ideas more critically here than in any other forum.”

Professor Crim is an elected member of the National Academy of Sciences and the American Academy of Arts and Sciences. He is an Alfred P. Sloan Research Fellow and a Max Planck Research Award recipient.

Early in his career, Crim worked in private industry at the Western Electric Company and in government at Los Alamos National Laboratory. For the past 25 years, he has been a professor at the University of Wisconsin in Madison, where he has received numerous awards for excellence in teaching. John Frederick, the president of TSRC, notes that “Crim is s very clear, very enthusiastic professor, and a great public presenter.”

This season’s Town Talks finale, “Antimatter – Can it take us to the stars?” will be given next week by Nicholas Digiacomo, physicist and entrepreneur, formerly with Los Alamos and CERN, on Tuesday, August 12th, same time 6:00 – 7:15 pm, same place, the Wilkinson Public Library in the Program Room.

For more information visit www.telluridescience.org or email nana@naisbitt.com or phone 970-369-0585.

Nana Naisbitt
Telluride Watch
Executive Director of the Pinhead Institute
nana@naisbitt.com
August 4, 2003