An attosecond is a ridiculously brief sliver of time – a scant billionth of a billionth of a second. This may seem too short to have any practical applications, but at the atomic level, where electrons zip and jump about, these vanishingly short timescales are crucial to a deeper understanding of science.
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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