It will be easier for scientists to observe how atoms and molecules behave thanks to the contributions of physics researchers at Kansas State University's James R. Macdonald Laboratory.
K-State's Charles "Lew" Cocke, university distinguished professor of physics, and Pedrag Ranitovic, research associate, worked with colleagues from the University of Colorado and the University of Tsukuba in Japan. Their research in finding a way to observe the movement of molecules in real time is featured in the Sept. 7 issue of the journal Science.
Cocke said the work featured is basic research that will help chemists better understand how and why reactions take place, and someday could allow scientists to control the movement of particles. This development could lead to the creation of tailor-made molecules to improve health care, energy and security.
Pulses of infrared and ultraviolet light have been used to observe particles as they undergo chemical reactions. But to observe the movement of these particles in real time, the K-State researchers and their colleagues explored the use of soft X-rays in short pulses. Cocke said studying the behavior of particles this way would be like seeing who won a foot race by photographing the runners every few seconds.
For the experiment, the researchers used a laser apparatus at the University Colorado to hit nitrogen molecules with pulses of soft X-rays. Nitrogen is convenient, cheap and had the right properties for the experiment, Cocke said, adding that the research also has been done with oxygen and carbon dioxide. He said that the soft X-rays that hit the nitrogen are lower energy than ones dentists use on teeth, but they're high enough energy to take the electrons off of atoms.
The pulses of soft X-rays were shorter in time than the time that it took for the pieces of the particles to move, giving a clearer glimpse of their movements in real time. As the X-rays took the electrons off of the atoms, the researchers hit the nitrogen with ultraviolet and infrared waves.
"You can hit it with the short burst of UV and get the particles to excite," Cocke said. "You can 'tickle' it at various times and see what happens in between the pulses. This is the first time this approach has been used to take an electron off the atom prior to the tickle. Before, we were not able to do that. The ultimate goal is to be able to control what the molecules do."
K-State is working on its own version of this laser apparatus at the Macdonald Laboratory. The apparatus of mirrors, pumps and detectors used to study tiny particles fills about half of the lab's room, Cocke said. The laser will need a carefully designed target chamber, which is K-State's area of expertise, he said.
"This part of the experiment is a very important part of our facility," Cocke said. "This is where we're the experts -- we've been working with the target chamber for 20 years."
Courtesy of K-State Media Relations