Image of pulsing motion of the electron pair in a helium atom.

Electronic pas de deux

 

The motion of the two electrons in the helium atom can be imaged and controlled with attosecond-timed laser flashes

Physicists in Heidelberg have filmed the pulsing motion of the electron pair 
in a helium atom.
At 15.3 femtoseconds (fs) the two electrons are close to the nucleus (centre of image) 
and then move away from it. 
The colour indicates the probability of finding one electron at position A (vertical axis) 
and the second electron at position B (horizontal axis) 
on a line drawn through the atom (along the polarisation direction of the laser). 
At 16.3 femtoseconds they arrive back at their original position again; 
they thus move with a beat of around one femtosecond.

(Christian Ott, Andreas Kaldun, Luca Argenti, Philipp Raith, Kristina Meyer, Martin Laux, Yizhu Zhang, Alexander Blättermann, Steffen Hagstotz, Thomas Ding, Robert Heck, Javier Madroñero, Fernando Martín, Thomas Pfeifer. Reconstruction and control of a time-dependent two-electron wave packet.) 

Nature, 2014; 516 (7531): 374 DOI: 10.1038/nature14026

Credit: © MPI for Nuclear Physics

Electrons are hard to get a hold of. Physicists cannot determine their precise location in an atom, but they can narrow down the region where the charge carriers are most probably located. When electrons move, this brings about a change to the regions where the electrons have the highest probability of being located. In some electronic states -- physicists call them superposition states -- this motion manifests itself as a pulsing with a regular beat.

"Although we do not directly image where the electrons are," explains Thomas Pfeifer, "the visible pulse provides us with the relative phase of the superposition state." The phase describes the to and fro of an oscillation, and hence the rhythmic motion of the electron pair. In this case it tells the physicists at which point of their natural pas de deux around the helium atom the electrons are at a given moment.

At this point, at the latest, attosecond physics would create new tools for chemistry as well.

#thankfully shared and cited:http://www.sciencedaily.com/releases/2014/12/141218103219.htm