UI professor analyzing the components of clouds in space

UI professor analyzing the components of clouds in space

Ben McCall can't travel into the vast reaches of space to find out what interstellar clouds are made of and how they work on a molecular level, so he brings the cosmic bodies to his University of Illinois lab.

The clouds' chemistry, anyway.

The makeup of the stuff that exists between the stars is of interest for a number of reasons, not the least of which is that interstellar clouds may provide the birth material for new stars, as well as planets, as they contract under the weight of their own gravity and get denser and denser.

An interstellar cloud at some point probably formed our own solar system, and its composition might have included the water essential for the formation of life.

"To me, it's just intrinsically interesting to try to understand the chemistry in a very different environment," McCall, a UI chemistry and astronomy professor, said recently.

Interstellar clouds also are a fount of so-called carbocations positively charged hydrocarbon molecules.

On Earth, carbocations are often an intermediate step when one type of molecule is converted to another, important in the creation of synthetic molecules for purposes ranging from making high-tech materials to developing new drugs.

McCall, originally from St. Louis, has been at the UI about 2< 1/2> years. He's already racked up a Presidential Early Career Award for Scientists and Engineers and, in October, a $625,000 science fellowship from the David and Lucile Packard Foundation.

The foundation cited McCall's ongoing development of new techniques to isolate and study carbocations in particular.

"McCall is one of the most spectacular young physical chemists in the United States," UI Chemistry Department head Steve Zimmerman said on the occasion of the Packard award. "His research has the potential to revolutionize our understanding of the spectra of ions in the gas phase and of the chemistry of interstellar clouds."

McCall started studying chemistry at Caltech, where he earned his bachelor's degree in 1995. But he'd had an interest in astronomy, as well as a telescope, as a kid, and he led a Caltech student team that developed an experiment to study gamma ray bursts for a shuttle flight.

It was exposure to techniques for employing chemistry to study space astrochemistry in graduate school at the University of Chicago that set him on his current course, however. He ended up making his own program to earn joint doctorates in chemistry and in astronomy and astrophysics.

"I wanted to be a real astronomer as well as a real chemist," McCall said.

The ions of interstellar clouds exist in a plasma, a gaslike state produced naturally by our sun and the stars, as well as artificially in neon signs and plasma TVs.

McCall and his students re-create those conditions in a plasma chamber at his UI lab and then probe the ions they've made inside with lasers, a technique called ultrasensitive direct absorption spectroscopy.

The laser light is absorbed to varying degrees, depending on the structures and motions of what it hits. The variations give the researchers light signatures, or fingerprints, for the ions they're studying.

They compare those fingerprints to visible light, infrared and radio telescope data collected on interstellar clouds in order to discern the clouds' makeup.

"We can relate (the data from space) to what we do in the laboratory," McCall said. "It's a type of remote sensing."

Ultimately, he and his colleagues hope to be able to better isolate ions akin to finding the proverbial needle in a haystack, considering that they're generally grouped with millions of regular molecules and to study them at cold temperatures rather than room temperature or above. In part, they plan to do that by getting the ions to move in a stream, using an electric field, and at supersonic speed.

The combination, promising but still in development, should provide clearer pictures of ions in an environment even more like space.

Meanwhile, McCall might help make the UI an astrochemistry hotbed. He's started a seminar series on topics in the field, aimed at both the Astronomy and Chemistry departments, and a cross-listed course that in its first semester drew chemistry and astronomy students and even a few budding physicists.

He and colleagues have begun work on a graduate program in astrochemistry, and he would like to start a lab course applying his techniques in conjunction with the UI's historic observatory and its 12-inch telescope.

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