Free Newsletters - Space News - Defense Alert - Environment Report - Energy Monitor
. 24/7 Space News .

36 in one fell swoop as researchers observe impossible ionization
by Staff Writers
Hamburg, Germany (SPX) Nov 14, 2012

File image: xenon atom.

Using the world's most powerful X-ray laser in California, an international research team discovered a surprising behaviour of atoms: with a single X-ray flash, the group led by Daniel Rolles from the Center for Free-Electron Laser Science (CFEL) in Hamburg (Germany) was able to kick a record number of 36 electrons at once out of a xenon atom.

According to theoretical calculations, these are significantly more than should be possible at this energy of the X-ray radiation. The team present their unexpected observations in the journal "Nature Photonics". CFEL is a collaboration of DESY, the Max Planck Society and the University of Hamburg.

When an atom loses electrons, it acquires a positive electric charge - it becomes ionized. This ionization is stronger the more electrons are torn from the atom. The researchers led by Rolles, who is working in the Max Planck Advanced Study Group at CFEL, had fired intense X-ray laser flashes from the Linac Coherent Light Source (LCLS) at the US National Accelerator Laboratory SLAC in California at atoms of the noble gas xenon.

With 1.5 kiloelectronvolts (1.5 keV), the particles of light (photons) of the X-ray radiation had around a thousand times more energy than visible light. When such a high-energy photon hits an electron in the xenon atomic shell, its energy is transferred to the electron. Through this collision, the electron can be ejected from the atomic shell - depending on how strongly it is bound.

According to calculations, up to 26 of the 54 electrons of the noble gas could be kicked out at the energy employed, the remaining are too strongly bound. In fact, however, the researchers found that up to 36 electrons flew from the atoms. "To our knowledge, this is the highest ionization that has ever been achieved in an atom using a single electromagnetic pulse," says Rolles, who will lead a Helmholtz Young Investigators group at DESY in the future. "Our observation shows that the existing theoretical approaches have to be modified."

What causes the "impossible" ionization is a so-called resonance: in the energy range used, xenon electrons can absorb a lot of X-ray radiation. Some are thus directly ejected from the atom, while others go into an excited, i.e. more energetic, state, but are still bound to the atom.

When one of the excited electrons returns to its initial state, in turn energy is released, which can give another excited electron the necessary extra nudge to kick it out of the atom. In rare cases, the already excited electron is hit by a second photon from the X-ray flash, and so ejected from the atomic shell.

"The LCLS experiment produced an unexpected and unprecedented charge state by ejecting dozens of electrons from an atom," says graduate student and co-author Benedikt Rudek from the Max Planck Advanced Study Group and the Max Planck institute for nuclear physics in Heidelberg, who analysed the data.

"The absorbed energy per atom was more than twice as high as expected." This resonance effect is particularly strong for xenon at an energy of 1.5 keV. Consequently, even at a higher energy of 2 keV, the researchers observed only less strongly ionized atoms. Based on the measurements, the CFEL researchers refined a computational model that allows them to calculate such resonances in heavy atoms. In subsequent experiments, scientists used the LCLS to examine, among others, krypton and molecules that contain heavy atoms, as co-author Artem Rudenko from Kansas State University says, who headed one of these follow-up experiments.

The observations also have practical significance for research: "Our results give a recipe for maximizing the loss of electrons in a sample," says Rolles. This can be desirable or undesirable. "For instance, researchers can use our results if they're interested in creating a very highly charged plasma."

When investigating biological samples, however, most researchers should avoid the resonance regions of such heavy atoms. "Most biological samples have some heavy atoms embedded," says Rolles. In the resonance region, such samples can be damaged very quickly in these places, which may affect the image quality.

For their precision measurements the team used a special experimental station that was built by the Max Planck Advanced Study Group (ASG) at CFEL together with the Max Planck institutes for nuclear physics, for medical research and semiconductor laboratory. The CFEL-ASG Multi-Purpose chamber (CAMP) was shipped to SLAC in 40 crates weighing a total of 11 tons and was installed at the LCLS for three years. It was used in more than 20 experiments.

Along with researchers from the Center for Free-Electron Laser Science, several Max Planck institutes, DESY and the US National Accelerator Laboratory SLAC, the study involved scientists from about a dozen institutions in Germany, France, Japan and the USA.


Related Links
Helmholtz Association of German Research Centres
Linac Coherent Light Source facility
Space Technology News - Applications and Research

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

Sweet approach may produce metal casting parts, reduce toxicity
Corvallis OR (SPX) Nov 14, 2012
Based on a new discovery by researchers at Oregon State University, the world's multi-billion dollar foundry industry may soon develop a sweet tooth. This industry, that produces metal castings used in everything from water pumps and jet engines to railroad and automobile parts, dates back thousands of years to before Greek and Roman times. It was important in the advance of human civilization, ... read more

China's Chang'e-3 to land on moon next year

Moon crater yields impact clues

Study: Moon basin formed by giant impact

NASA's LADEE Spacecraft Gets Final Science Instrument Installed

Mars orbiter back online after system swap

What Arctic Rocks Say About Mars: An Interview with Hans Amundsen

More Driving And Imaging At 'Matijevic Hill'

Curiosity Team Switches Back to Earth Time

SciTechTalk: All work and no play?

Get some bed rest - all 21 days of it

Latest China military hardware displayed at airshow

Obama Win Keeps NASA's Space Plans on Course

Mr Xi in Space

China plans manned space launch in 2013: state media

China to launch manned spacecraft

Tiangong 1 Parked And Waiting As Shenzhou 10 Mission Prep Continues

Russia loses contact with satellites, space station

Cut in Russian link to space station not serious: NASA

Crew Prepares for Spacewalk After Progress Docks

Crew Preparing for Cargo Ship, Spacewalk

Arianespace's fourth Spaceport mission with Soyuz ready for fueling

Ariane 5's sixth launch of 2012

Ariane 5 is poised for Arianespace's launch with the EUTELSAT 21B and Star One C3 satellites

Ariane 5 orbits EUTELSAT 21B and Star One C3 satellites

Lost in Space: Rogue Planet Spotted?

Lowell Astronomer, Collaborators Point The Way For Exoplanet Search

Lonely planet: Orphan world spotted in deep space

Discovery of a Giant Gap in the Disk of a Sun-like Star May Indicate Multiple Planets

Chinese LED firm plans record investment in Taiwan

US to station powerful radar, space telescope in Australia

Afghan women learn literacy through mobile phones

36 in one fell swoop as researchers observe impossible ionization

The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement