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 a 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
another.
"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 said.
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