New X-ray tool proves timing is everything

Feb 20, 2013 by Glenn Roberts Jr.
This illustration shows an optical laser pulse (red) and an X-ray laser pulse (light blue) striking a sample. The use of synchronized laser pulses in the same experiment, known as the "pump-probe" technique, is common for SLAC's Linac Coherent Light Source X-ray laser, and a timing tool developed by an international team allows more precise measurements of the arrival time of laser pulses at LCLS. Credit: Greg Stewart / SLAC National Accelerator Laboratory

(Phys.org)—With SLAC's Linac Coherent Light Source X-ray laser, timing is everything. Its pulses are designed to explore atomic-scale processes that are measured in femtoseconds, or quadrillionths of a second. Determining the instant in time at which the laser strikes a sample, either by itself or in concert with another laser pulse, can be vital to the success of an experiment.

In the Feb. 17 issue of , researchers detail a new set of tools that better pinpoints the arrival time of X-ray and other to within a few femtoseconds of accuracy.

"The development of such a timing tool as well as the demonstration of a few- is opening a large field of applications in trying to resolve ultrafast dynamics in physics, chemistry and biology," said Marion Harmand of the German Electron Synchrotron (DESY) in Hamburg, Germany, the paper's lead author.

Many LCLS experiments rely on conventional laser systems, known as optical lasers, that excite and prepare samples in the instant before they are struck by the ultrabright, ultrafast X-ray laser pulses. These experiments are often referred to as "pump-probe." The optical laser pulse "pumps" the sample to a desired state, and the X-ray laser pulses serve as a high-resolution "probe" of the sample's properties at the molecular scale.

In the LCLS experiment conducted in December 2011, researchers installed two sets of timing tools to detect changes in samples using X-ray and optical laser pulses. The pulses were ultimately directed to a sample of bismuth metal, triggering atomic vibrations that provided a final test of the timing tools.

This diagram shows the path of X-ray pulses (blue) and pulses from a separate laser (red) and a sequence of measurement tools that provide a highly accurate gauge of the arrival times of each laser. Credit: Nature Photonics

Creating those separate interaction points where the X-ray and pulses passed through and overlapped was a challenge, Harmand said. "This was like running three experiments in parallel."

Aspects of the experiment were demonstrated earlier in "soft" (lower-energy) X-ray experiments at the LCLS and at FLASH, an X-ray laser in Germany.

"For the first time we proved these timing tools can work in the hard X-ray regime, and can dramatically improve the accuracy of measurements," Harmand said.

Researchers sampled more than 15,000 sets of laser pulses, and the correlation in measurements from the separate timing tools provided the high degree of accuracy. Some of the tools used in the experiment have been adopted at several LCLS experimental stations.

New experiments are planned to explore other materials and operating conditions at LCLS that could benefit from the timing tools, the researchers noted.

Explore further: New technique detects microscopic diabetes-related eye damage

More information: www.nature.com/nphoton/journal/vaop/ncurrent/full/nphoton.2013.11.html

Related Stories

FLASH Imaging Redux: Nano-Cinema is Born

Jul 08, 2008

Flash imaging of nanoscale objects undergoing ultrafast changes is now a technical possibility, according to a recent paper published in the June 22 edition of Nature Photonics. The results are a direct precur ...

X-rays capture electron 'dance'

Jan 31, 2013

(Phys.org)—The way electrons move within and between molecules, transferring energy as they go, plays an important role in many chemical and biological processes, such as the conversion of sunlight to energy ...

Organic crystals put laser focus on magnetism

Jul 27, 2012

(Phys.org) -- In the first successful experiment of its type at SLAC's Linac Coherent Light Source, scientists used terahertz frequencies of light to change the magnetic state of a sample and then measured ...

First atomic X-ray laser created

Jan 25, 2012

Scientists working at the U.S. Department of Energy's (DOE) SLAC National Accelerator Laboratory have created the shortest, purest X-ray laser pulses ever achieved, fulfilling a 45-year-old prediction and ...

Exploring middle ground of solids and liquids

Nov 16, 2012

(Phys.org)—In experiments at SLAC National Accelerator Laboratory's Linac Coherent Light Source X-ray laser, researchers made snapshots of atomic-scale fluctuations in liquids and glasses. The results are ...

Recommended for you

Robotics goes micro-scale

Apr 17, 2014

(Phys.org) —The development of light-driven 'micro-robots' that can autonomously investigate and manipulate the nano-scale environment in a microscope comes a step closer, thanks to new research from the ...

High power laser sources at exotic wavelengths

Apr 14, 2014

High power laser sources at exotic wavelengths may be a step closer as researchers in China report a fibre optic parametric oscillator with record breaking efficiency. The research team believe this could ...

User comments : 0

More news stories

Could 'Jedi Putter' be the force golfers need?

Putting is arguably the most important skill in golf; in fact, it's been described as a game within a game. Now a team of Rice engineering students has devised a training putter that offers golfers audio, ...

Impact glass stores biodata for millions of years

(Phys.org) —Bits of plant life encapsulated in molten glass by asteroid and comet impacts millions of years ago give geologists information about climate and life forms on the ancient Earth. Scientists ...