In a paper accepted for publication in the American Institute of Physics' journal Review of Scientific Instruments,
a team of researchers describes an advanced experimental system that
can generate attosecond bursts of extreme ultraviolet light. Such pulses
are the shortest controllable light pulses available to science. With
these pulses, according to the researchers, it's possible to measure the
dynamics of electrons in matter in real-time. Advances in attosecond
science may enable scientists to verify theories that describe how
matter behaves at a fundamental level, how certain important chemical
reactions – such as photosynthesis – work. Additional advances may
eventually lead to the control of chemical reactions.
"Understanding how matter works at the level of its electrons is
likely to lead to new scientific tools and to novel technologies," said
Felix Frank, of Imperial College in London and one of the authors on the
paper. "In the future, this knowledge could help us to make better
drugs, more efficient solar cells, and other things we can't yet
foresee."
The researchers were able to produce these pulses by a process called
high harmonic generation (HHG). The fundamental technology driving
their setup is a high-power femtosecond laser system (femtoseconds are
three orders of magnitude longer than attoseconds). The near infrared
femtosecond laser pulses are corralled through a waveguide and a series
of specialized mirrors, causing them to be compressed in time. With
their waveforms precisely controlled, these compressed pulses are then
focused into a gas target, creating an attosecond burst of extreme
ultraviolet radiation. The experimental system developed by the
researchers is able to accurately measure the attosecond
pulses and deliver them to a variety of experiments in conjugation with
other precisely synchronized laser pulses. "Though it incorporates many
novel features, our system builds on a decade of research conducted by
physics groups around the world," said John Tisch, lead scientist
developing the technology at Imperial College.
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