Laser Creates First EUV Attosecond Pulses
PARIS, April 9, 2012 — For the first time, incredibly fast laser pulses could make it possible to observe ultrarapid phenomena such as the motion of electrons in matter.
Laboratoire d'Optique Appliquèe (LOA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA) and Laboratoire pour l'Utilisation des Lasers Intenses (Ecole Polytechnique/UPMC) collaborated on a technique that produces attosecond pulses in the extreme ultraviolet (EUV) wavelengths in a reproducible way.
The experimental setup. (Image © Antonin Borot)
Events such as ionization, or an electron moving from one energy level to another, occur at the order of attoseconds (10-18 seconds, or a billionth of a billionth of a second). To see an event like this happen, and to study the path and evolution of the particle, you need to produce light pulses at that order of magnitude, something akin to a camera taking photofinishes at a race.
To create such a light pulse, the team, led by LOA, created a superefficient light source that could deliver 1000 identical femtosecond (10-15 seconds) long pulses per second. The researchers focused the 1-μm-wide beam on a silicon target. The intensity of the beam turned the solid silica into plasma of the same density. The laser excited the electrons within the plasma, causing them to emit EUV radiation that can be recorded.
Electronic trajectories and EUV radiation induced by the laser field. (Image ©Antonin Borot)
The team plans to continue to refine its laser source to create even faster radiation in the shorter X-ray domain of the spectrum.
A paper on the work is available online through Nature Physics.
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