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Science Forum Index » Physics Forum » Article: Snapshot taken of the tiniest time interval
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| Robert Karl Stonjek |
 Posted: Mon Mar 01, 2004 2:55 pm |
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Snapshot taken of the tiniest time interval
Electron movements pinned down to the split second.
26 February 2004
MARK PEPLOW
This article is from the news section of the journal Nature
Physicists in Austria say that they have observed events separated by
the shortest time interval ever, and plan to use the technique to study
atomic phenomena.
A group led by Ferenc Krausz of Vienna University of Technology used
pulses of laser light to watch electrons moving around atoms, and were
able to distinguish events that took place 100 attoseconds - or 10^-16
seconds - apart [1].
Krausz and his team say that the research could improve understanding of
the role of electrons in superconductivity and in giant
magnetoresistance, a magnetic effect used in data-storage devices. "It's
only on the attosecond timescale that you see these things happening,"
says Roger Falcone, a physicist at the University of California,
Berkeley.
The attosecond (10^-18 s), also known as a quintillionth of a second, is
the timescale of atomic events. In Niels Bohr's 1913 model of a hydrogen
atom, it takes about 150 attoseconds for an electron to orbit the
proton.
Krausz used ultraviolet-light pulses of 250-attosecond duration to
excite electrons in atoms of neon, raising them to a higher energy
level. These electrons come out of the atoms with a range of different
momenta. A second pulse of light, delivered just after the first, then
gives the electrons an extra jolt. Changing the delay between these two
pulses produces a different distribution of momentum values for the
electrons, which the scientists measured with a sensitive electron
detector called a 'streak camera'. Comparing these distributions gave
the team a snapshot of how the electrons differed when hit with an early
or late second pulse.
Krausz thinks that the technique could soon be refined to track events a
few tens of attoseconds apart, telling physicists how electrons
rearrange themselves inside an atom when they move between different
orbits.
Recent progress in using fleeting laser flashes to study short time
scales has opened up the field of femtochemistry, in which the motion of
atoms and molecules is tracked on the femtosecond (10^-15 s) timescale,
to see how they rearrange themselves during chemical reactions. Probing
even shorter timescales could provide more insight.
"Every time we get shorter pulses, chemists say that we don't really
need them," says David Klug, a photochemist at Imperial College, London.
"But then they find a way to use them. Once it becomes convenient,
people will find applications for it."
References
[1] Kienberger, R. et al. Atomic transient recorder. Nature, 427, 817 -
821, doi:10.1038/nature02277 (2004).
From Nature
http://www.nature.com/nsu/040223/040223-7.html
Comment:
The application that springs to my mind is in CPU design. A 10^-15
interval, trivially converted to clock speed, comes out at one million
gig. Current maximum CPU speed is around 3.2 gig.
--
Posted by
Robert Karl Stonjek. |
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| GR_Learner@GR.grv |
| Posted: Wed Mar 03, 2004 2:44 pm |
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"Robert Karl Stonjek" <stonjek@ozemail.com.au> wrote in message
news:%yM0c.83726$Wa.52191@news-server.bigpond.net.au...
Quote: Snapshot taken of the tiniest time interval
The Planck time?
Quote: Electron movements pinned down to the split second.
26 February 2004
MARK PEPLOW
This article is from the news section of the journal Nature
Physicists in Austria say that they have observed events separated by
the shortest time interval ever, and plan to use the technique to study
atomic phenomena.
A group led by Ferenc Krausz of Vienna University of Technology used
pulses of laser light to watch electrons moving around atoms, and were
able to distinguish events that took place 100 attoseconds - or 10^-16
seconds - apart [1].
Nope. |
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