Scientists measure shortest ever time interval

Scientists claim to have measured the shortest-ever time interval.

Updated: Jun 25, 2010, 15:11 PM IST

Berlin: German scientists claim to have
measured the shortest-ever time interval by discovering the
tiniest duration an electron takes to leave the atom.

Until now, it has been assumed that the electrons start
moving out of the atom immediately after the impact of the
photons or light particles. This effect, known as
photoemission, was explained by Albert Einstein more than
hundred years ago.

But physicists from the Technische Universitaet Muenchen,
the Ludwig-Maximilians-Universitaet Muenchen and the
Max-Planck-Institute of Quantum Optics found that when light
is absorbed by atoms, the electrons become excited and get
ejected from the atom if the photons carry sufficient energy.

However, there is a time delay in electrons being
separated from atoms which they claim is the shortest time
interval measured to date.

Using their ultra-short time measurement technology, the
physicists fired pulses of near-infrared laser light at atoms
of the noble gas neon.

The findings appeared in the journal Science.

The atoms were simultaneously hit by extreme ultraviolet
pulses with duration of 180 attoseconds, liberating
electrons from their atomic orbitals.

Then they recorded when the excited electrons left the
atom. They found that electrons from different atomic
orbitals, although excited simultaneously, leave the atom with
a small but measurable time delay of about twenty attoseconds.

"One attosecond is one billionth of one billionth of a
second, an unimaginable short interval of time. But after
excitation by light one of the electrons leaves the atom
earlier than the other. Hence we were able to show that
electrons "hesitate" briefly before they leave an atom,"
explains Reinhard Kienberger, one of the researchers.

Ferenc Krausz, another author of the study, said their
research showed that the electrons not only interact with
their atomic nucleus, but also they are influenced by one

"Our investigations shed light on the electrons`
interactions with one another on atomic scale," said Krausz.

"These to-date poorly understood interactions have a
fundamental influence on electron movements in tiniest
dimensions, which determine the course of all biological and
chemical processes, not to mention the speed of
microprocessors, which lie at the heart of computers."

To this end, the fastest measuring technique in the world
is just about good enough: the observed 20-attosecond time
offset in the ejection times of electrons is the shortest time
interval that has ever been directly measured, the scientists