This is actually rather important. A electron beam vortex isproduced but it is also been tightly managed allowing incredibleprecision.
The real bottom line is that this precision and scale allows us toenvisage the manipulation of single molecules themselves. Thisappears to be the tool able to do just that.
Thus this work has now truly begun.
ElectronMicroscopes With a Twist
by Staff Writers
Vienna, Austria(SPX) Nov 07, 2012
http://www.spacedaily.com/reports/Electron_Microscopes_With_a_Twist_999.html
Nowadays, electronmicroscopesare an essential tool, especially in the field of materials science.At TU Vienna, electron beams are being created that possess aninner rotation, similarly to a tornado. These "vortex beams"cannot only be used to display objects, but to investigatematerial-specific properties - with precision on a nanometer scale. Anew breakthrough in research now allows scientists to producemuch more intense vortex beams than ever before.
In a tornado, theindividual air particles do not necessarily rotate on their own axis,but the air suction overall creates a powerful rotation. The rotatingelectron beams that have been generated at TU Vienna behave in a verysimilar manner.
Quantum Tornado: theElectron as a Wave
In order tounderstand them, we should not think of electrons simply as minusculepoints or pellets, as in that case they could at most rotate on theirown axis. Vortex beams, on the other hand, can only be explained interms of quantum physics: the electrons behave like a wave, andthis quantum wave can rotate like a tornado or a water current behinda ship's propeller.
"After the vortexbeam gains angular momentum, it can also transfer this angularmomentum to the object that it encounters", explained Prof.Peter Schattschneider from the Institute of Solid State Physics at TUVienna.
The angular momentumof the electrons in a solid object is closely linked to its magneticproperties. For materials science it is therefore a huge advantage tobe able to make statements regarding angular momentum conditionsbased on these new electron beams.
Beams Rotate - WithMasks and Screens
PeterSchattschneider and Michael Stoger-Pollach (USTEM, TU Vienna) havebeen working together with a research group from Antwerp on creatingthe most intense, clean and controllable vortex beams possible in atransmission electron microscope.
The first successeswere achieved two years ago: at the time, the electron beam was shotthrough a minuscule grid mask, whereby it split into three partialbeams: one turning right, one turning left and one beam that did notrotate.
Now, a new, much morepowerful method has been developed: researchers use a screen, half ofwhich is covered by a layer of silicon nitride. This layer is so thinthat the electrons can penetrate it with hardly any absorption,however they can be suitably phase-shifted. "After focusingusing a specially adapted astigmatic lens, an individual vortex beamis obtained", explained Michael Stoger-Pollach.This beam is moreintense by one order of magnitude than the vortex beams that we havebeen able to create to date.
"Firstly, we donot split the beam into three parts, as is the case with a grid mask,but rather, the entire electron stream is set into rotation.Secondly, the grid mask had the disadvantage of blocking half of theelectrons - the new special screen does not do this", saidStoger-Pollach.
Thanks to the newtechnology, right and left-rotating beams can now be distinguished ina reliable manner - previously this was only possible withdifficulty. If we now add a predetermined angular momentum to eachright and left-rotating beam, the rotation of one beam is increased,while the rotation of the other beam decreases.
Electron microscopeswith a twist
Thisnew technology was briefly presented by the research team in the"Physical Review Letters" journal. In future, theaim is to apply the method in materials science.
Magnetic propertiesare often the focus of attention, particularly in the case of newlydeveloped designer materials. "A transmission electronmicroscope with vortex beams would allow us to investigate theseproperties with nanometric precision", explained PeterSchattschneider.
More exoticapplications of vortex beams are also conceivable: in principle,it is possible to set all kinds of objects in rotation - evenindividual molecules - using these beams, which possess angularmomentum. Vortex beams could therefore also open new doors innanotechnology.
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