Posted: April 6, 2007

Scientists observe escaping electrons for first time

(Nanowerk News) For the first time, researchers have observed electrons using the energy of a laser to escape the forces binding them to an atom.
The work was partly funded by the EU under the Marie Curie section of the Sixth Framework Programme (FP6), and is published in the journal Nature.
Normally, strong forces keep electrons in their orbits around the nucleus of atoms. Trying to overcome this force is like climbing a steep mountain. However, in the world of quantum physics, there is an escape route: with a bit of help from the energy of a laser field, the electrons can tunnel through the 'mountain' to freedom.
This tunnelling process is so fast (it lasts just a few hundred attoseconds, an attosecond being a billionth of a billionth of a second) that until now scientists have lacked the means to observe it in real time.
Together with colleagues from Germany, Austria, the Netherlands and Russia, Ferenc Krausz of the Max Planck Institute for Quantum Optics fired a pulse of ultraviolet light just 250 attoseconds long at neon atoms, timed to match the oscillations of a red laser pulse. The researchers were able to measure the levels of neon ions which had lost an electron during these brief moments, and so observe the tunnelling process indirectly.
'These experiments don't just provide us with the first ever insight into the dynamics of electron tunnelling,' commented Professor Krausz, 'We have also shown that the movement of electrons in atoms or molecules can be observed in real time with the help of laser field-induced tunnelling.'
The researchers hope that understanding how electrons behave at this scale will lead to new developments in microelectronics, the development of compact x-ray light sources, biological imaging and radiotherapy.
Source: Cordis
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