Electron filmed for first time ever
Date: Saturday, February 23, 2008 @ 12:15:20 UTC
Topic: Science
 Now it is possible to see a movie of an electron. The movie shows how
an electron rides on a light wave after just having been pulled away
from an atom. This is the first time an electron has ever been filmed,
and the results are presented in the latest issue of Physical Review Letters.
Previously it has been
impossible to photograph electrons since their extremely high
velocities have produced blurry pictures. In order to capture these
rapid events, extremely short flashes of light are necessary, but such
flashes were not previously available. With the use of a newly
developed technology for generating short pulses from intense laser
light, so-called attosecond pulses, scientists at the Lund University
Faculty of Engineering in Sweden have managed to capture the electron
motion for the first time.
View video: avi or mov.
“It takes about 150 attoseconds for an electron to circle the nucleus of an atom. An attosecond is 10-18
seconds long, or, expressed in another way: an attosecond is related to
a second as a second is related to the age of the universe,” says Johan
Mauritsson, an assistant professor in atomic physics at the Faculty of
Engineering, Lund University. He is one of seven researchers behind the
study, which was directed by him and Professor Anne L’Huillier.
View video: avi or mov.
With the aid of another laser
these scientists have moreover succeeded in guiding the motion of the
electron so that they can capture a collision between an electron and
an atom on film.
“We have long been promising the research community that we will be
able to use attosecond pulses to film electron motion. Now that we have
succeeded, we can study how electrons behave when they collide with
various objects, for example. The images can function as corroboration
of our theories,” explains Johan Mauritsson.
These scientists also hope to find out more about what happens with
the rest of the atom when an inner electron leaves it, for instance how
and when the other electrons fill in the gap that is created.
“What we are doing is pure basic research. If there happen to be
future applications, they will have to be seen as a bonus,” adds Johan
Mauritsson.
The length of the film corresponds to a single oscillation of the
light, but the speed has then been ratcheted down considerably so that
we can watch it. The filmed sequence shows the energy distribution of
the electron and is therefore not a film in the usual sense.
Previously scientists have studied the movements of electrons using
indirect methods, such as by metering their spectrum. With these
methods it has only been possible to measure the result of an
electron’s movement, whereas now we have the opportunity to monitor the
entire event.
It has been possible to create attosecond pulses for a couple of
years now, but not until now has anyone managed to use them to film
electron movements, since the attosecond pulses themselves are too weak
to take clear pictures.
“By taking several pictures of exactly the same moment in the
process, it’s possible to create stronger, but still sharp, images. A
precondition is for the process to be repeated in an identical manner,
which is the case regarding the movement of an electron in a ray of
light. We started with a so-called stroboscope. A stroboscope enables
us to ‘freeze’ a periodic movement, like capturing a hummingbird
flapping its wings. You then take several pictures when the wings are
in the same position, such as at the top, and the picture will turn out
clear, despite the rapid motion,” clarifies Johan Mauritsson.
More information: http://www.atto.fysik.lth.se/
Source: Swedish Research Council
Via: http://www.physorg.com/news122897584.html
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