Researchers using the Linac Coherent Light Source (LCLS) at the U.S. Department of Energy's (DOE) SLAC National Accelerator Laboratory have found a way to strip most of the electrons from xenon atoms, creating a "supercharged," strongly positive state at energies previously thought too low.
The findings, which defy expectations and theory, could help scientists deliberately induce the high levels of damage needed to study extreme states of matter or ward off damage in samples they're trying to image. The results were reported this week in Nature Photonics.
While the powerful X-rays of LCLS inevitably destroy the samples being studied, delaying damage even for millionths of billionths of a second can prove critical in producing detailed images and other data.
"Our results give a 'recipe' for maximizing the loss of electrons in a sample," said Daniel Rolles, a researcher for the Max Planck Advanced Study Group at the Center for Free-Electron Laser Science in Hamburg, Germany, who led the experiments. "For instance, researchers can use our findings if they're interested in creating a very highly charged plasma. Or, if the supercharged state isn't part of the study, they can use our findings to know what X-ray energies to avoid."
Just as a stretched guitar string can vibrate and sustain a note, a specific tuning of the laser's properties can cause atoms and molecules to resonate. The resonance excites the atoms and causes them to shake off electrons at a rate that otherwise would require higher energies.
While it is common knowledge that triggering resonances in atoms will affect their charged states, "it was not clear to anybody what a dramatic effect this could have in heavy atoms when they are being ionized by a source like LCLS," Rolles said. "It was the highest charge state ever observed with a single X-ray pulse, which shows that the existing theoretical approaches have to be modified."
|Contact: Andy Freeberg|
DOE/SLAC National Accelerator Laboratory