Won the 1986 Nobel Prize in chemistry for using chemi-luminescence of molecules to explain energy relationships in chemical reactions
"The most exciting thing in the twentieth century is science. Young people ask me if this country is serious about science. They aren’t thinking about the passport that they will hold, but the country that they must rely on for support and encouragement."
At about eight o’clock on a Thursday night in 1956, John Polanyi walks into the janitorial closet he calls a laboratory. The young University of Toronto lecturer can’t expect much more; he isn’t even an assistant professor yet. Polanyi’s graduate student, Ken Cashion, who is wearing one of his many short-sleeved Hawaiian shirts, says, “Well, I think we’re ready for another run.”
“Did you check the seals on the ‘Stokes’?” asks Polanyi, glancing at the giant vacuum pump thwapping away in the corner.
“Yes. They’re not great, but I think she’ll hold for one more experiment,” says Cashion.
The fresh-air scent of ozone catches Polanyi’s nose as Cashion opens the hydrogen valve and flicks a switch. For this experiment they need hydrogen gas as single atoms. (Hydrogen occurs naturally in pairs of hydrogen atoms.) Ken has scrounged the electrical discharge unit from an old neon sign. By jolting the flow of hydrogen with 6,000 volts of electricity, Polanyi and Cashion break the gas into single hydrogen atoms. Polanyi likes the soft, pinky neon glow that hydrogen makes, but he worries about its explosive power. Some hasty calculations they had made the day before indicated the lab wouldn’t blow up, but they hadn’t been entirely sure.
As it turned out, the experiment was a success and Polanyi and Cashion recorded something that no one had ever seen before — a tiny amount of light produced by the reaction of hydrogen with chlorine. This light was chemiluminescence. Because Polanyi understood the source of the feeble light emissions in his experiment, he was able to predict exactly what kind of energy needed to be applied to make this chemical reaction take place. Over the years he expanded his theories for other reactions, which unexpectedly led to the development of powerful new kinds of chemical lasers. Ultimately that experiment in a broom closet resulted in a Nobel Prize.
When Polanyi was 11 years old his father, who was a chemistry professor at the University of Manchester in England, sent him to Canada so that he would not be hurt when Germany was bombing Britain during World War II. Polanyi stayed with a family in Toronto for three years. He remembers going on a bicycle camping trip and reading the Count of Monte Cristo and War and Peace. He was not interested in science as much as in sociology and literature.
In school Polanyi thought it was sort of dumb just to follow instructions for a chemistry experiment and get the “right” result. He would always fool around and try to vary things, just to see what would happen. He was very curious. The problem was that he would always get the “wrong” result. This would get him in trouble and his teachers often said he lacked the discipline to learn. He kept at it, however, and eventually became very interested in science. But he likes to tell kids that a lifelong commitment to something need not start out with a love affair.
After the war Polanyi went back to Manchester, where he completed high school and obtained his university education. He returned to Canada after that, first for a job at the National Research Council, where he worked for a while with Gerhard Herzberg, who was studying energy states of molecules. After a stint at Princeton University in New Jersey, Polanyi took a job lecturing at the University of Toronto in 1956.
Throughout his career as a scientist, Polanyi has been very active and outspoken in the Peace Movement. In a 2003 article in the Globe and Mail newspaper, he criticized the proposed trillion-dollar U.S. National Missile Defence system, saying “National Missile Defence points the world down the wrong path; it is the path of fortress-building, which, in the 21st century, is hopelessly anachronistic. Unchecked, weapons and counter weapons lead only to the development of further weapons.”
According to Polanyi, science teaches a number of lessons concerning peace. First, none of us is in full possession of the truth, but we all work together, groping toward it. Second, for scientists, the pursuit of that truth is to be achieved through reason, not through violence. But he adds, “Of course, we shall always need faith. Reason would hardly suffice to get us out of bed in the morning. We need faith in what the day holds. But faith alone, as we have learnt, is inhuman, crushing all in its path. Reason listens, as well as talks. Of its nature it acknowledges the existence of others, since it triumphs only by persuading others. And that is how science advances. Not by scientific ‘proof’ ... We do not go to scientific meetings to announce results, but to debate them. We can never be sure. That is a lesson that science has to offer humanity.”
As a physical chemist, John Polanyi studies the physics of chemical reactions — the energy states and the movements of molecules during the moment of reaction. This field of chemistry is called reaction dynamics. His work has helped answer the question, how do you get a chemical reaction to go? Do you tickle the molecules, or do you slam them together? It turns out that in some cases tickling works, in others you just have to slam them against each other.
As Polanyi says, “The importance of this work is that we have a picture of reacting atoms in the transition state.” The transition state of a chemical reaction is the brief period, often only millionths of a second long, when the starting materials have combined together but have not yet completely transformed themselves into the products of the reaction. This knowledge of reaction dynamics has allowed chemists to fine-tune reaction conditions to improve yields in chemical processes.
In one recent series of experiments, Polanyi and his research team worked with the chemical methyl bromide and silicon to learn how to “print” patterns of atoms. They use million-dollar scanning tunnelling microscopes that work at very cold temperatures of minus 223°C. They can manipulate and see individual molecules. Polanyi and his research team are able to weakly attach methyl bromine atoms to an underlying silicon crystal in neat, circular patterns of 12 molecules per circle. Then, by exposing the molecules to ultraviolet light, they have discovered the bromine atoms will form strong chemical bonds with the silicon underneath while the methyl part (CH3) breaks off and floats away.
Polanyi says, “We can now photoprint molecular-scale patterns permanently onto silicon chips. Could be useful.” He is fascinated by the notion that physical spacing of chemical reactions can be controlled like this. “One can dream of a molecular-scale printing press in which the pattern is present in the ink and the press is the light.” Potential future applications in the world of nanotechnology and microchip fabrication are likely.
1. The Nobel Prize-winning experiment: A lot of energy is given off when hydrogen and chlorine react to form hydrogen chloride, but nobody knew much about this energy when Polanyi arrived at the University of Toronto in 1956 and decided to study it. Little did he realize that this simple reaction would lead to a Nobel Prize 30 years later.
2. Transition state: For a brief instant at the moment of reaction, the molecules are in a transition state as they turn into new chemicals. Polanyi’s experiments led to a picture of the arrangement of atoms in the transition state. At the time, it was known that molecules had three kinds of motion: spinning or rotational energy; buzzing or vibrational energy; and the energy of movement from one point to another, or translational energy. What was entirely unknown was the relationship between these three types of energy during a chemical reaction. Polanyi’s experiments began a new field of chemistry called reaction dynamics, the prediction of the pattern of the motion of molecules in a chemical reaction.
3. Chemiluminescence: Polanyi used an infrared spectrometer to measure the light energy emitted by the newborn products of the chemical reaction. The product molecules emit a very feeble light called chemiluminescence, which Polanyi recorded. He used this information to distinguish between vibrational and rotational energies in the molecule. His understanding of light emitted by chemical reactions later allowed him to propose vibrational and chemical lasers, the most powerful sources of infrared radiation ever developed.
4. The “Lab”: Polanyi’s graduate student assistant, Ken Cashion, set up the Nobel Prize-winning apparatus and was the first to see the result of the experiment. The two researchers had to “borrow” the spectrometer from other scientists who would have been furious if they had realized how it would be dismantled and modified for the experiment.
Polanyi believes that one of the great mysteries is the molecular basis of life. He thinks that in the future we will have devices that operate in the molecular dimension, allowing observations of chemical reactions under much more widely varying conditions than is currently possible. He says, “If, perhaps, you are worried that by the time today’s scientists leave the scene and your turn comes there will be nothing left to discover, stop worrying. What we know is surely only a tiny fraction of what remains to be known. At the centre of the atom, in the nucleus of the living cell and at the outer edges of the universe lie new worlds awaiting their discoverer.”
So You Want to Be a Physical Chemist
A few years ago, in a German magazine, Polanyi described his life as a research chemist. “I have had a life in which I have been paid to play. I haven’t been paid much, but my toys continue to be the best.” However, he went on to point out that the very expensive, fancy scientific instruments he gets to “play with” can be temperamental, and sometimes they don’t work at all. “That is worrying, since I have to make new discoveries if I am to be allowed to continue doing science, which is what I love to do,” he said. “So you can imagine the delight when finally that wretched machine for looking at molecules works, and I and my students get a glimpse of something nobody has ever seen before. We share for a moment in the relief and wonder that Christopher Columbus must have felt when, just at the moment that all seemed to be lost, a smudge of land appeared on the horizon. At that moment we are united with all the discoverers of history and are proud to call ourselves scientists.”
And what is Polanyi’s secret for succeeding as a scientist? “Above all, I would say, by wishing to do so,” he says. People of many different talents have succeeded in science, but nobody has succeeded who did not passionately want to do so.
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