For the first time ever, scientists have created microscopic movies of liquids getting vaporized by an X-ray laser. The research was conducted at the Department of Energy's SLAC National Accelerator Laboratory and could help future studies take advantage of X-ray lasers in order to capture atomic snapshots of the numerous lightning-fast processes that occur in nature.
"Understanding the dynamics of these explosions will allow us to avoid their unwanted effects on samples," said Claudiu Stan of Stanford PULSE Institute, a joint institute of Stanford University and SLAC. "It could also help us find new ways of using explosions caused by X-rays to trigger changes in samples and study matter under extreme conditions. These studies could help us better understand a wide range of phenomena in X-ray science and other applications."
The team used SLAC's Linac Coherent Light Source (LCLS), the world's brightest X-ray laser, to obtain their snapshots. Using this ultra-bright laser, the team blew up samples of liquids and captured the explosive interactions in microscopic detail.
For every X-ray pulse that hit the liquid, the team took an image that was timed from five billionths of a second to one ten-thousandth of a second following the pulse. Using these images, they created movies of the fascinating process.
"Thanks to a special imaging system developed for this purpose, we were able to record these movies for the first time," said Sébastien Boutet from LCLS and co-author of the study. "We used an ultrafast optical laser like a strobe light to illuminate the explosion, and made images with a high-resolution microscope that is suitable for use in the vacuum chamber where the X-rays hit the samples."
The footage shows an X-ray pulse tearing the drop of liquid apart, creating a cloud of smaller particles and vapor. This vapor makes its way toward neighboring drops and damages them, in turn causing them to migrate to the droplets nearest to them for a merger.
In addition, the footage shows the X-ray pulse punching a hole into a stream of liquid, creating a gap that gradually grows, causing the ends of the jet to form into a liquid film. This film shapes into an umbrella, eventually folding back and merging with the jet.
Using the data, the team was able to create mathematical models to predict how the explosive behavior varies between experiments depending on factors such as pulse energy, drop size and jet diameter. The team hopes that these models will help in future studies that utilize X-rays to capture nature's fastest processes.
The findings were published in the May 23 issue of Nature Physics.
All of the videos can be viewed at SLAC's YouTube channel here.
