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In two recent experiments, SLAC researchers demonstrated new methods for using attosecond pulses in pump probe experiments and generating high-power attosecond X-ray pulses. Credit: Greg Stewart/SLAC National Accelerator Laboratory
A team of scientists at the Department of Energy’s SLAC National Accelerator Laboratory is developing new methods to investigate the finest details of the universe at extraordinary speeds.
In previous research, researchers developed a way to produce X-ray laser bursts lasting several hundred attoseconds (or billionths of a billionth of a second). This method, called X-ray laser-enhanced attosecond pulse generation (XLEAP), allows scientists to investigate how electrons spinning around molecules initiate key processes in biology, chemistry, materials science and more.
Now, led by SLAC scientists Agostino Marinelli and James Cryan, the team has developed new tools to use these attosecond pulses in innovative ways: the first use of attosecond pulses in bomb probe experiments and the production of the most powerful beam pulses X of attoseconds already reported. The experiments, conducted at SLAC’s Linac Coherent Light Source (LCLS) X-ray free electron laser and published in two articles in Nature PhotonicsIt could revolutionize fields ranging from chemistry to materials science, offering insights into the fastest movements within atoms and molecules.
A new method for measuring ultrafast phenomena
In the first development, researchers introduced a new approach to conducting “bomb probe” experiments with attosecond X-ray pulses. These experiments, which aim to measure ultrafast events smaller than a trillionth of a second, involve exciting atoms with a “pump” pulse followed by probing them with a second pulse to observe the resulting changes.
This technique allowed scientists to track and measure the movement of electrons within atoms and molecules – a critical process that influences chemical reactions, material properties and biological functions. They achieved this by generating pairs of laser pulses in two colors and meticulously controlling the delay between them to just 270 attoseconds.
“This capability opens up new opportunities to study the interaction of light with matter at the most fundamental level,” said Cryan. “It’s exciting because it has evolved into a practical tool, allowing us to see the dynamics of electrons that were previously beyond our reach. We are now observing processes that occur on time scales that approximate the time it takes for light to pass through a molecule .”
In a recent paper, researchers used this technique to observe electrons moving in real time in liquid water. Future studies will apply this method to various molecular systems, refining the precision of these measurements and expanding their application across scientific disciplines.
More information:
Zhaoheng Guo et al, Experimental demonstration of attosecond pump-probe spectroscopy with an X-ray free-electron laser, Nature Photonics (2024). DOI: 10.1038/s41566-024-01419-w
Paris Franz et al, Terawatt-scale attosecond X-ray pulses from a cascaded superradiant free-electron laser, Nature Photonics (2024). DOI: 10.1038/s41566-024-01427-w
Diary information:
Nature Photonics
