Ultrafast laser could improve reaction control
laser spectroscopy to detect the energy level of atoms in a gas,
which could have applications in the analysis and synthesis of
chemicals.
The team, from JILA (a joint institute of the US Commerce Department's National Institute of Standards and Technology and the University of Colorado at Boulder) has developed an efficient, low-cost way to measure the energy levels of atoms in a gas with extremely high accuracy, and simultaneously detect and control transitions between the levels as fast as they occur.
Described in the 18 November online issue of Science Express, the method uses ultrafast pulses of laser light - like a high speed camera - to record in real-time the energy required to boost an atom's outer electrons from one orbital pattern to another.
The pulses are short, and this enables scientists to track precisely the fraction of atoms in each energy state and how those populations change with time. Moreover, the atoms respond to subsequent laser pulses cumulatively - in other words the energy adds up over time - and this allows fine-tuning to affect specific orbital patterns of interest with a much lower power laser than usual.
"All of chemistry depends on the configurations of these outer electrons," according to the authors of the study. "The technique promises to make it easier for scientists to systematically understand the radiation 'signatures' (or spectra) given off by atoms and molecules as their electrons jump between different energy levels."
Ultimately, it should allow improved control of the complex chain of events that combines atoms into desired compounds, they added.
The JILA team specialises in applying so-called 'frequency combs' to practical scientific problems. The laser system used in the current work emits a hundred thousand different infrared frequencies at once in individual pulses lasting just femtoseconds (quadrillionths of a second).
The JILA researchers used the laser to precisely study the electron energy levels within an ultracold gas of rubidium atoms. The ability to probe atoms with many different laser frequencies simultaneously and to monitor atom responses in real time should allow scientists to
