Watching electrons move in real time

Sep 21, 2010

At its most basic level, understanding chemistry means understanding what electrons are doing. Research published in the Journal of Chemical Physics not only maps the movement of electrons in real time but also observes a concerted electron and proton transfer that is quite different from any previously known phase transitions in the model crystal, ammonium sulfate. By extending X-ray powder diffraction into the femtosecond realm, the researchers were able to map the relocation of charges in the ammonium sulfate crystal after they were displaced by photoexcitation.

"Our prototype experiment produces a sort of 'molecular movie' of the atoms in action," says author Michael Woerner of the Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie in Germany. "The time and spatial resolution is now at atomic time and length scales, respectively."

Electron positions were mapped by observing the diffraction of X-ray pulses lasting tens of femtoseconds (quadrillionth of a second). Positions of protons and other nuclei were deduced from the locations of regions of high . Within the crystal, the excited electrons transferred from the sulfate groups to a tight channel within crystal matrix. This channel was stabilized by the transfer of protons from adjacent ammonium groups into the channel. This transfer mechanism had not been previously observed or proposed, and the researchers had expected to see much smaller displacements.

According to Woerner, the technique should be applicable to structural studies of materials ranging from biomolecules to . "We expect that the technique will be applied to many interesting material systems." He says. "In principle, femtosecond X-ray powder diffraction can be applied to any crystalline form of matter. Only the complexity of crystals and the presence of heavy elements, which reduces the penetration depth of X-rays, set some constraints."

Explore further: New insights found in black hole collisions

More information: The Article, "Concerted electron and proton transfer in ionic crystals mapped by femtosecond x-ray powder diffraction" by Michael Woerner, Flavio Zamponi, Zunaira Ansari, Jens Dreyer, Benjamin Freyer, Mirabelle Premont-Schwarz, and Thomas Elsaesser is published in the Journal of Chemical Physics. See: jcp.aip.org/jcpsa6/v133/i6/p064509_s1

Provided by American Institute of Physics

5 /5 (13 votes)
add to favorites email to friend print save as pdf

Related Stories

Unveiling the structure of microcrystals

Oct 04, 2007

Microcrystals take the form of tiny grains resembling powder, which is extremely difficult to study. For the first time, researchers from the European Synchrotron Radiation Facility (ESRF) and the Centre National ...

Powders show their strength

Oct 09, 2007

[PIC=:left]Growing a single crystal of a protein can be very difficult. Thanks to recent developments, a powder sample may be enough to solve a structure.

Clocking Ultra-fast Electron Bunches

Jul 30, 2010

(PhysOrg.com) -- Brookhaven researchers have developed a device that acts like a high-tech stopwatch for speedy packs of electrons just trillionths of a second long. This new diagnostic tool could aid in the ...

Recommended for you

New insights found in black hole collisions

Mar 27, 2015

New research provides revelations about the most energetic event in the universe—the merging of two spinning, orbiting black holes into a much larger black hole.

X-rays probe LHC for cause of short circuit

Mar 27, 2015

The LHC has now transitioned from powering tests to the machine checkout phase. This phase involves the full-scale tests of all systems in preparation for beam. Early last Saturday morning, during the ramp-down, ...

Swimming algae offer insights into living fluid dynamics

Mar 27, 2015

None of us would be alive if sperm cells didn't know how to swim, or if the cilia in our lungs couldn't prevent fluid buildup. But we know very little about the dynamics of so-called "living fluids," those ...

Fluctuation X-ray scattering

Mar 26, 2015

In biology, materials science and the energy sciences, structural information provides important insights into the understanding of matter. The link between a structure and its properties can suggest new ...

Hydrodynamics approaches to granular matter

Mar 26, 2015

Sand, rocks, grains, salt or sugar are what physicists call granular media. A better understanding of granular media is important - particularly when mixed with water and air, as it forms the foundations of houses and off-shore ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.