ERIE, Pa. — Before boiling the water for that next pot of pasta, look at the flame: What researchers know about combustion – heat breaks molecules into reactive fragments, which rapidly combine with oxygen, creating energy – skips over some of the mystery that makes dinner possible.
“Combustion is a complex process,” said Jay Amicangelo, a professor of chemistry at Penn State Behrend. “It’s a series of steps, with hundreds of reactions, and we’ve not fully mapped it out. We know what we start with, and we know what the end products are, but we still don’t completely understand what’s happening in the middle.”
A three-year, $330,000 grant from the U.S. National Science Foundation (NSF) is funding Amicangelo’s study of one step in that process. By isolating a single atom of hydrogen and exposing it to a ring molecule, he can create a hydrogenated radical — an unstable molecule that produces one of the chemical reactions believed to be essential to combustion.
A better understanding of these radicals could lead to efficiencies in combustion and hydrogenation, a process that is used to produce food and pharmaceuticals, Amicangelo said. But the molecules are elusive.
“You can’t see them,” he said. “And you can’t store them in a bottle.”
To create and capture hydrogenated radicals, Amicangelo uses a custom-built infrared spectrometer. He lowers the temperature in a small chamber on the instrument to between 10 and 20 Kelvins — approximately -442 and -424 degrees Fahrenheit — and reduces the atmospheric pressure within the chamber.
“We create an ultra-high vacuum,” he said. “We are basically creating the conditions you would find in interstellar space.”
He then sprays argon gas into the chamber. At the low temperature, argon becomes a solid, creating a film over the chamber’s window. The unstable and otherwise short-lived radical is preserved in the film.
Molecules absorb light in distinct ways, creating unique spectral patterns – a sort of infrared signature. By shining an infrared beam on the preserved radicals, Amicangelo can identify them through their unique signature. That can be useful to astronomers, who use spectral lines to study the light coming from different objects in space.
Amicangelo used some of the NSF funding to purchase a new spectrometer. The grant also supports student researchers, who assist with the experiments. They quickly learn that science is less consistent than the experiments in a traditional chemistry class, Amicangelo said.
“In a teaching lab, we know how the experiment is going to end,” he said. “We’ve done it before, often hundreds of times. In a research lab, the outcome is less certain.
Sometimes, the experiment works. Sometimes, it fails. Often, researchers have to troubleshoot and vary the conditions.
“In that setting, students quickly learn that science isn’t a straight line,” Amicangelo said. “It takes a lot of work, a lot of patience and a lot of dedication.”