To your left is Stewart Novick, a Ph.D. and professor of physical chemistry at Wesleyan. What he is standing next to, and looking quite content with, is a pulsed-jet Fabry-Pérot Fourier-transform microwave spectrometer (FTMS from now on). Both have impressive titles, but, as the latter is crucial to Prof. Novickís research, it may be useful to explain a few things about the machine first.

The FTMS is used to measure the spectra--the rotational energy, or frequency--of "exotic" molecules. These are highly reactive free radicals or molecules with very weak chemical bonds that do not exist on Earth under normal circumstances for very long, if ever. The FTMS provides an atmosphere for these molecules to "live," however briefly, giving people like Prof. Novick and his group of graduate and undergraduate students the opportunity to study them. The main part of the machine is a vacuum chamber, about one meter long, which is brought down to 10^-6 Torr. Thatís about as close as you can come on Earth to a total vacuum, and it means that there are basically no other molecules in the chamber to interfere with the molecules being tested, which are very fragile and would fall apart immediately if they were to collide with other molecules. The gases (all the molecules studied are studied in their gaseous form, which is the simplest form of matter, molecularly speaking) are released into the chamber through a supersonic nozzle which gives them speeds multiple times the speed of sound. This gives the molecules great amounts of energy in the forward motion, effectively sucking away energy in all other capacities, since energy is conserved in a closed system (and you thought youíd never have to deal with the law of conservation of energy again--ha!) Therefore, upon expansion into the chamber, they come out at tremendously frigid temperatures--a mere one degree above absolute zero. "So we have a paradoxical state of matter," Prof. Novick explains. "Itís still a gas, but normally at those kinds of temperatures itís a dead solidÖItís a gas thatís very cold--itís only a gas in that the molecules are isolated from each other. But itís very cold, very little relative motion." This means that these weakly bound molecules wonít fall apart for a little while--they donít collide with each other, either, giving Prof. Novick and his group the time they need to read their spectra.

And how does one read the spectra of a free radical or weakly bound molecule floating around the evacuated Fabry-Pérot cavity of an FTMS? With a microwave, of course (a photon, not an oven)--a whole bunch of them, in fact. The whole process requires careful timing, which is handled by a computer; for, while the machine does manage to maintain the proper conditions to keep these unstable molecules alive, they do not remain so indefinitely (their lifespan is only about a thousandth of a second), and everything must happen quickly and precisely--otherwise, the molecules will fall apart before data can be collected, which is done as follows: Microwaves are emitted into the chamber as the gas molecules enter. A microwave will hit a molecule and excite it to its next energy level, or rotational frequency. Molecules rotate, and the speed with which they rotate is their rotational frequency. According to quantum mechanics, molecules can only rotate at certain rates--if a molecule were a car, it could go maybe 5 mph, 10 mph, 20 mph, and 35 mph, but not 15 mph, or anything else in between these specific speeds. When you excite a molecule to the next rotational frequency, you can measure the energy separation between the two frequencies--youíre measuring the gaps in between, as though they were rungs on a ladder and you were measuring the space between two rungs with a tape measure.

What you get from this procedure is a graph like the one to your left. The results from such a graph are then transformed into a series of numbers which indicate the frequencies of the molecules at various energy levels--so for, say, a C¹³CCCH molecule, you may come up with numbers such as 9448.165 MHz, 9464.915 MHz, or 9502.090 MHz. To the untrained eye, these numbers look like just a bunch of scientific jumble, but they tell Prof. Novick and his group a great deal about the molecules they were drawn from. There are two main areas he studies using microwave spectroscopy. One involves astrophysics and the investigation of the molecular make-up of dense interstellar clouds. These are clouds of dust and gases floating in space, "called dense but theyíre really very tenuous by our Earth standards. So these dense interstellar clouds are better than some of the best vacuums on Earth, but for astronomical purposes theyíre dense," Prof. Novick explains. Theyíre dense with gases, and dusty enough that we canít see into them with any current technology. More importantly, light canít penetrate them because of this dust, which makes them the "chemical nurseries" of the galaxies. Chemicals develop in these clouds that couldnít otherwise exist in space--they would be broken up by the starsí ultraviolet light, or photodissociated. So all sorts of free radicals appear in these clouds, and astronomers want to know what exactly these chemicals are; however, since light does not penetrate these clouds, they cannot use conventional methods of determining what the chemicals are. Instead, they scan the clouds for microwave emissions--beginning to see the connection?

Prof. Novick helps the astronomers to look for these chemicals. Using the chemicals already known to exist in the interstellar clouds, they take guesses as to what else might be in there. Prof. Novick and his students then make these molecules in the FTMS and find their spectra--"laboratory astro-chemistry," he calls it. They give the frequencies to the astronomers, which they then use to scan the clouds&emdash;if the frequencies turn up, then the chemicals must actually be in the clouds. A chart outside the Professorís office shows the structure of every molecule theyíve made, some of them starred, indicating that they have actually been found in space using his frequencies--and there are more than a few stars. Recently they made H₂C₅ and H₂C₆, found the spectra, released the frequencies to astronomers, and before his report had even been published, H₂C₆ had been found in space. "Thatís one of the successes where we actually looked for something we thought should be there, and based off our frequencies, they have been found. There are a couple of others that we have made that have not yet been found, some that probably wonít be, some Iím sure should be," he commented.

The other area he investigates is the structure of the molecules for its own sake, ultimately to learn how they would behave as a liquid, the most complicated state of matter. Finding the spectra of a molecule is not only useful in astro-chemistry--it also helps to determine the structure the molecule. "Quantum mechanics tells us that there are formulas that relate the size and mass of a molecule to its allowed rotational frequencies," Prof. Novick explains. What the FTMS measures is known as the moment of inertia, which is equal to the masses of the molecule times the distance they are apart squared--"it just turns out it's an important thing," says Prof. Novick. When the spectra of a molecule are taken, you get a series of these numbers from which you can deduce the mass and distances of the molecule, and thus its structure. Prof. Novick and his students perform this procedure to determine the structures of various weakly bound complexes, such as bonds between argon atoms and between argon and acetone. These bonds do not normally exist on Earth--argon, being a rare gas, does not normally form chemical bonds with other atoms--and so the FTMS produces these unusual chemicals as a gas, so that we may eventually deduce their behavior as a liquid.

The machine sits in the basement of the Hall-Atwater building at Wesleyan, in a room cluttered with dozens of pressurized gas tanks, assorted diagrams, calculations, computers, and a small motor that helps evacuate the chamber, and provides a constant grumble of background noise. There are only 25 or so in the world (Wesleyan's machine shop has built four of them). The beast itself resembles a trussed up trash can laid on its side, with wires, coils and pressure guages protruding in every direction. There are several small windows in the sides, through which you can actually see the reactions taking place in the chamber--flashes of light are emitted during the process, different colors depending on the gases used.
 

Click here if you would like to see Professor Novick's homepage.