Researchers at the Department of Energy’s SLAC National Accelerator Laboratory are pioneering new techniques to delve into the universe’s minuscule intricacies with remarkable speed.
In earlier studies, the team devised a method to generate X-ray laser bursts lasting several hundred attoseconds (a billionth of a billionth of a second). Known as X-ray laser-enhanced attosecond pulse generation (XLEAP), this innovation enables scientists to scrutinize the rapid electron movements within molecules, unlocking insights into biology, chemistry, materials science, and beyond.
Building upon this foundation, led by SLAC scientists Agostino Marinelli and James Cryan, the team has introduced novel methodologies leveraging these attosecond pulses. Their groundbreaking work marks the inaugural application of attosecond pulses in pump-probe experiments and the production of the most potent attosecond X-ray pulses on record. Published in two articles in Nature Photonics, these experiments have the potential to revolutionize diverse fields, from chemistry to materials science, by offering unprecedented glimpses into the fastest atomic and molecular motions.
A novel approach to measuring ultrafast phenomena
In their first breakthrough, researchers devised a fresh strategy for conducting “pump-probe” experiments using attosecond X-ray pulses. These experiments, aimed at observing events shorter than a trillionth of a second, involve stimulating atoms with a “pump” pulse and subsequently probing them with another pulse to detect resulting changes.
This technique enables scientists to track and quantify electron movements within atoms and molecules—a pivotal process influencing chemical reactions, material characteristics, and biological functions. By generating pairs of laser pulses in two distinct colors and precisely controlling the delay between them to as little as 270 attoseconds, researchers can now observe electron dynamics previously beyond reach.
In a recent study, this method was employed to monitor real-time electron movements in liquid water. Future investigations will apply this approach to various molecular systems, refining measurement accuracy and broadening its utility across scientific domains.
Generating high-power attosecond pulses
The team’s second breakthrough focused on producing high-power attosecond pulses using a method called “super-radiance,” achieving power levels nearing one terawatt. This process, leveraging a cascading effect in an X-ray free-electron laser, significantly amplifies pulse power.
The heightened intensity of these pulses enables scientists to explore novel states of matter and observe phenomena occurring at even shorter time scales.
“These are the most powerful attosecond X-ray pulses ever reported. The intensity of these pulses allows us to explore entirely new regimes of X-ray science,” noted Marinelli. “We’ve expanded the boundaries of X-ray pulse energy, reaching power levels that unlock new experimental frontiers.”
The team aims to further refine this technology to enhance stability and control over these high-power pulses, with the goal of extending their application across diverse scientific realms.
Propelling scientific inquiry forward
These breakthroughs push the limits of observational and measurement capabilities, laying the groundwork for future scientific discoveries that could revolutionize our understanding of the natural world.
Observing atoms and electrons in motion holds promise for designing new materials with tailored properties for technology, energy, and other fields. Understanding electron dynamics during chemical reactions can inform intelligent chemical design principles.
“These studies not only deepen our understanding of physics but also pave the way for future innovations that could transform our understanding of electron-driven processes,” emphasized Cryan. “Each attosecond pulse we generate provides a fresh glimpse into nature’s fundamental building blocks, unveiling dynamics previously hidden from view. We anticipate many more exciting discoveries ahead.”
