Artificial intelligence deciphers detector “clouds” to accelerate materials research

A machine learning algorithm automatically extracts information to speed up – and extend – the study of materials with X-ray pulse pairs.

X-rays can be used like a superfast, atomic-resolution camera, and if researchers shoot a pair of X-ray pulses just moments apart, they get atomic-resolution snapshots of a system at two points in time. Comparing these snapshots shows how a material fluctuates within a tiny fraction of a second, which could help scientists design future generations of super-fast computers, communications, and other technologies.

Resolving the information in these X-ray snapshots, however, is difficult and time intensive, so Joshua Turner, a lead scientist at the Department of Energy’s SLAC National Accelerator Center and Stanford University, and ten other researchers turned to artificial intelligence to automate the process. Their machine learning-aided method, published October 17 in Structural Dynamics, accelerates this X-ray probing technique, and extends it to previously inaccessible materials.

“The most exciting thing to me is that we can now access a different range of measurements, which we couldn’t before,” Turner said.

Handling the blob

When studying materials using this two-pulse technique, the X-rays scatter off a material and are usually detected one photon at a time. A detector measures these scattered photons, which are used to produce a speckle pattern – a blotchy image that represents the precise configuration of the sample at one instant in time. Researchers compare the speckle patterns from each pair of pulses to calculate fluctuations in the sample.

“However, every photon creates an explosion of electrical charge on the detector,” Turner said. “If there are too many photons, these charge clouds merge together to create an unrecognizable blob.” This cloud of noise means the researchers must collect tons of scattering data to yield a clear understanding of the speckle pattern.

“You need a lot of data to work out what’s happening in the system,” said Sathya Chitturi, a Ph.D. student at Stanford University who led this work. He is advised by Turner and coauthor Mike Dunne, director of the Linac Coherent Light Source (LCLS) X-ray laser at SLAC. 

Read more on the SLAC website

Image: A speckle pattern typical of the sort seen at LCLS’s detectors

Credit: Courtesy Joshua Turner

Researchers resolve decades-long debate about shock-compressed silicon with unprecedented detail

They saw how the material finds a path to contorting and flexing to avoid being irreversibly crushed.


Silicon, an element abundant in Earth’s crust, is currently the most widely used semiconductor material and is important in fields like engineering, geophysics and plasma physics. But despite decades of studies, how the material transforms when hit with powerful shockwaves has been a topic of longstanding debate.

“One might assume that because we have already studied silicon in so many ways there is nothing left to discover,” said Silvia Pandolfi, a researcher at the Department of Energy’s SLAC National Accelerator Laboratory. “But there are still some important aspects of its behavior that are not clear.”

Now, researchers at SLAC have finally put this controversy to rest, providing the first direct, high-fidelity view of how a single silicon crystal deforms during shock compression on nanosecond timescales. To do so, they studied the crystal with X-rays from SLAC’s Linac Coherent Light Source (LCLS) X-ray laser. The team published their results in Nature Communications on September 21st. What they learned could lead to more accurate models that better predict what will happen to certain materials in extreme conditions.

“This is a great example of an experiment that’s necessary to better understand certain materials,” said SLAC scientist Arianna Gleason, who was the principal investigator. “You have to start simple, with single crystals, to know what you’re tracking and understand it in really detailed ways before you can build up complexity to give way to, say, the next semiconductor of the 21st Century that will allow the electronics industry to continue the remarkable progress seen in the past 50 years.”

Read more on the SLAC website

‘Diamond rain’ on giant icy planets could be more common than previously thought

Researchers at SLAC found that oxygen boosts this exotic precipitation, revealing a new path to make nanodiamonds here on Earth.

A new study has found that “diamond rain,” a long-hypothesized exotic type of precipitation on ice giant planets, could be more common than previously thought. 

In an earlier experiment, researchers mimicked the extreme temperatures and pressures found deep inside ice giants Neptune and Uranus and, for the first time, observed diamond rain as it formed.

Investigating this process in a new material that more closely resembles the chemical makeup of Neptune and Uranus, scientists from the Department of Energy’s SLAC National Accelerator Laboratory and their colleagues discovered that the presence of oxygen makes diamond formation more likely, allowing them to form and grow at a wider range of conditions and throughout more planets.

The new study provides a more complete picture of how diamond rain forms on other planets and, here on Earth, could lead to a new way of fabricating nanodiamonds, which have a very wide array of applications in drug delivery, medical sensors, noninvasive surgery, sustainable manufacturing, and quantum electronics.

“The earlier paper was the first time that we directly saw diamond formation from any mixtures,” said Siegfried Glenzer, director of the High Energy Density Division at SLAC. “Since then, there have been quite a lot of experiments with different pure materials. But inside planets, it’s much more complicated; there are a lot more chemicals in the mix. And so, what we wanted to figure out here was what sort of effect these additional chemicals have.”

The team, led by the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the University of Rostock in Germany, as well as France’s École Polytechnique in collaboration with SLAC, published the results today in Science Advances

Read more on the SLAC website

Introducing Stephen Streiffer

After decades of experience in the DOE lab system and as director of a leading synchrotron light source, he’s back to where he earned his PhD – with a much bigger mission.

Thirty years after earning his PhD at Stanford University, materials scientist Stephen Streiffer will be back on campus next week – this time with an outsized role to play. As Stanford’s new vice president for the Department of Energy’s SLAC National Accelerator Laboratory, he’ll play a key part in advising and supporting the lab as it carries out its scientific mission.

Streiffer comes to Stanford and SLAC after 24 years at Argonne National Laboratory, where he did research at the lab’s Advanced Photon Source, directed APS for eight years and most recently served as chief research officer and deputy lab director for science and technology.

So he’s more than familiar with both the national lab system and the importance of DOE Office of Science user facilities, like APS and SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) and Linac Coherent Light Source (LCLS), for both fundamental research and experiments with more immediate practical value.

Read Glennda Chui’s Q & A interview with Stephen on the SLAC website

Image: Stephen Streiffer, the new Stanford vice president for SLAC National Accelerator Laboratory

Credit: Mark Lopez, Argonne National Laboratory

Superconducting X-ray laser reaches operating temperature colder than outer space

The facility, LCLS-II, will soon sharpen our view of how nature works on ultrasmall, ultrafast scales, impacting everything from quantum devices to clean energy.

Nestled 30 feet underground in Menlo Park, California, a half-mile-long stretch of tunnel is now colder than most of the universe. It houses a new superconducting particle accelerator, part of an upgrade project to the Linac Coherent Light Source (LCLS) X-ray free-electron laser at the Department of Energy’s SLAC National Accelerator Laboratory.

Crews have successfully cooled the accelerator to minus 456 degrees Fahrenheit – or 2 kelvins – a temperature at which it becomes superconducting and can boost electrons to high energies with nearly zero energy lost in the process. It is one of the last milestones before LCLS-II will produce X-ray pulses that are 10,000 times brighter, on average, than those of LCLS and that arrive up to a million times per second – a world record for today’s most powerful X-ray light sources.

“In just a few hours, LCLS-II will produce more X-ray pulses than the current laser has generated in its entire lifetime,” says Mike Dunne, director of LCLS. “Data that once might have taken months to collect could be produced in minutes. It will take X-ray science to the next level, paving the way for a whole new range of studies and advancing our ability to develop revolutionary technologies to address some of the most profound challenges facing our society.”

With these new capabilities, scientists can examine the details of complex materials with unprecedented resolution to drive new forms of computing and communications; reveal rare and fleeting chemical events to teach us how to create more sustainable industries and clean energy technologies; study how biological molecules carry out life’s functions to develop new types of pharmaceuticals; and peek into the bizarre world of quantum mechanics by directly measuring the motions of individual atoms.

A chilling feat

LCLS, the world’s first hard X-ray free-electron laser (XFEL), produced its first light in April 2009, generating X-ray pulses a billion times brighter than anything that had come before. It accelerates electrons through a copper pipe at room temperature, which limits its rate to 120 X-ray pulses per second.

Read more on the SLAC website

An abundance of talents within the light source community

Monday Montage – Talents!

Our #LightSourceSelfies campaign has uncovered a wealth of talents among staff and users at light source facilities around the world. From skating to sculpting and painting to perennials, this Monday Montage illustrates the many hobbies and interests that those in our community enjoy in their spare time. With contributions from the ESRF, SESAME, LCLS and the European XFEL, this montage highlights the variety of activities that help people maintain a healthy work/life balance.

Advancing materials science with the help of biology and a dash of dish soap

High-speed X-ray free-electron lasers have unlocked the crystal structures of small molecules relevant to chemistry and materials science, proving a new method that could advance semiconductor and solar cell development.

Compounds that form tiny crystals hold secrets that could advance renewable energy generation and semiconductor development. Revealing the arrangement of their atoms has already allowed for breakthroughs in materials science and solar cells. However, existing techniques for determining these structures can damage sensitive microcrystals.

Now scientists have a new tool in their tool belts: a system for investigating microcrystals by the thousands with ultrafast pulses from an X-ray free-electron laser (XFEL), which can collect structural information before damage sets in. This approach, developed over the past decade to study proteins and other large biological molecules at the Department of Energy’s SLAC National Accelerator Laboratory, has now been applied for the first time to small molecules that are of interest to chemistry and materials science.

Researchers from the University of Connecticut, SLAC, DOE’s Lawrence Berkeley National Laboratory and other institutions developed the new process, called small molecule serial femtosecond X-ray crystallography or smSFX, to determine the structures of three compounds that form microcrystal powders, including two that were previously unknown. The experiments took place at SLAC’s Linac Coherent Light Source (LCLS) XFEL and the SACLA XFEL in Japan.

Read more on the SLAC website

Image: Artist’s rendition of the X-ray beam illuminating a solution of powdered metal-organic materials called chalcogenolates.

Credit: Ella Maru Studios

Science that just can’t wait until morning!

We know by now that coffee ranks highly on the list of things that help get light source users through their night shifts. This #LightSourceSelfie also include insights on positive thinking that can provide a much needed boost to get you through to the morning. These insights are brought to you from staff scientists at LCLS and NSLS-II in the USA and Diamond in the UK.

Someday you will get to play with those electrons!

Razib Obaid is a project scientist at the Linac Coherent Light Source (LCLS) at SLAC in California. LCLS is one of 7 free electron lasers in the collaboration. The facility takes X-ray snapshots of atoms and molecules at work, providing atomic resolution detail on ultrafast timescales to reveal fundamental processes in materials, technology and living things. Its snapshots can be strung together into “molecular movies” that show chemical reactions as they happen.

In Razib’s #LightSourceSelfie, he takes you into the Near Experimental Hall and describes the stunning equipment that is used to undertake the experiments, the science it enables and the possibilities for new science with the upgrade to LCLSII. Razib says, “The best thing about working at a light source is the ability as a user to tap into the enormous scientific resources and experience that exists among the staff and scientists. Not to mention the state of the art instrumentation that you have access to, to realise your science. To my younger self, I would say, keep studying quantum mechanics, someday you will get to play with those electrons.”

To learn more about LCLS, visit

Beginning your light source journey

Scientists who use synchrotrons such as the Advanced Light Source in California and CHESS at Cornell University, along with staff scientists at Free Electron Lasers in South Korea (the PAL-XFEL) and California (LCLS at SLAC), reflect on how they felt the first time they used a light source facility to conduct research experiments.  The expertise available from the staff scientists who work on the beamlines is also highlighted in this #LightSourceSelfie video.

Secrets of skyrmions revealed

Why skyrmions could have a lot in common with glass and high-temperature superconductors

Spawned by the spins of electrons in magnetic materials, these tiny whirlpools behave like independent particles and could be the future of computing. Experiments with SLAC’s X-ray laser are revealing their secrets.

Scientists have known for a long time that magnetism is created by the spins of electrons lining up in certain ways. But about a decade ago, they discovered another astonishing layer of complexity in magnetic materials: Under the right conditions, these spins can form little vortexes or whirlpools that act like particles and move around independently of the atoms that spawned them.

The tiny whirlpools are called skyrmions, named after Tony Skyrme, the British physicist who predicted their existence in 1962. Their small size and sturdy nature – like knots that are hard to undo – have given rise to a rapidly expanding field devoted to understanding them better and exploiting their strange qualities.

“These objects represent some of the most sophisticated forms of magnetic order that we know about,” said Josh Turner, a staff scientist at the Department of Energy’s SLAC National Accelerator Laboratory and principal investigator with the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC.

Read more on the SLAC website

Images: Top: Images based on simulations show how three phases of matter, including skyrmions – tiny whirlpools created by the spins of electrons – can form in certain magnetic materials. They are stripes of electron spin (left); hexagonal lattices (right); and an in-between phase (center) that’s a mixture of the two. In this middle, glass-like state, skyrmions move very slowly, like cars in a traffic jam – one of several discoveries made in recent studies by scientists at SLAC, Stanford, Berkeley Lab and UC San Diego. Bottom: Patterns formed in a detector during experiments that explored fundamentals of skyrmion behavior at SLAC’s Linac Coherent Light Source X-ray free-electron laser.

Credit: Esposito et al., Applied Physics Letters, 2020

Scientists capture a ‘quantum tug’ between neighbouring water molecules

The work sheds light on the web of hydrogen bonds that gives water its strange properties, which play a vital role in many chemical and biological processes.

Water is the most abundant yet least understood liquid in nature. It exhibits many strange behaviors that scientists still struggle to explain. While most liquids get denser as they get colder, water is most dense at 39 degrees Fahrenheit, just above its freezing point. This is why ice floats to the top of a drinking glass and lakes freeze from the surface down, allowing marine life to survive cold winters. Water also has an unusually high surface tension, allowing insects to walk on its surface, and a large capacity to store heat, keeping ocean temperatures stable.

Now, a team that includes researchers from the Department of Energy’s SLAC National Accelerator Laboratory, Stanford University and Stockholm University in Sweden have made the first direct observation of how hydrogen atoms in water molecules tug and push neighbouring water molecules when they are excited with laser light. Their results, published in Nature today, reveal effects that could underpin key aspects of the microscopic origin of water’s strange properties and could lead to a better understanding of how water helps proteins function in living organisms.

Read more on the LCLS website

Image: For these experiments, the research team (left to right: Xiaozhe Shen, Pedro Nunes, Jie Yang and Xijie Wang) used SLAC’s MeV-UED, a high-speed “electron camera” that uses a powerful beam of electrons to detect subtle molecular movements in samples.

Credit: Dawn Harmer/SLAC National Accelerator Laboratory

First detailed look at how charge transfer distorts a molecule’s structure

Charge transfer is highly important in most areas of chemistry, including photosynthesis and other processes in living things. A SLAC X-ray laser study reveals how it works in a molecule whose lopsided response to light has puzzled scientists for nearly a decade.

When light hits certain molecules, it dislodges electrons that then move from one location to another, creating areas of positive and negative charge. This “charge transfer” is highly important in many areas of chemistry, in biological processes like photosynthesis and in technologies like semiconductor devices and solar cells.

Even though theories have been developed to explain and predict how charge transfer works, they have been validated only indirectly because of the difficulty of observing how a molecule’s structure responds to charge movements with the required atomic resolution and on the required ultrafast time scales.

In a new study, a research team led by scientists from Brown University, the Department of Energy’s SLAC National Accelerator Laboratory and the University of Edinburgh used SLAC’s X-ray free-electron laser to make the first direct observations of molecular structures associated with charge transfer in gas molecules hit with light.

Molecules of this gas, called N,N′-dimethylpiperazine or DMP, are normally symmetric, with a nitrogen atom at each end. Light can knock an electron out of a nitrogen atom, leaving a positively charged ion known as a “charge center.”

Read more on the SLAC website

Image: In experiments with SLAC’s X-ray free-electron laser, scientists knocked electrons out of a molecule known as DMP to make the first detailed observations of how a process called charge transfer affects its molecular structure. Left: DMP is normally symmetric. Center: When a pulse of light knocks an electron out of one of its nitrogen atoms (blue spheres), it leaves a positively charged ion known as a charge center, shown in pink. This creates a charge imbalance that shifts the positions of atoms. Right: But within three trillionths of a second, the charge redistributes itself between the two nitrogen atoms until it evens out and the molecule becomes symmetric again.

Credit: Greg Stewart/ SLAC National Accelerator Laboratory

Surprising behavior of a fatty acid enzyme with potential biofuel applications

Derived from microscopic algae, the rare, light-driven enzyme converts fatty acids into starting ingredients for solvents and fuels.

Although many organisms capture and respond to sunlight, it’s rare to find enzymes – proteins that promote chemical reactions in living things – that are driven by light. Scientists have identified only three so far. The newest one, discovered in 2017, is called fatty acid photodecarboxylase (FAP). Derived from microscopic algae, FAP uses blue light to convert fatty acids into hydrocarbons that are similar to those found in crude oil.

“A growing number of researchers envision using FAPs for green chemistry applications because they can efficiently produce important components of solvents and fuels, including gasoline and jet fuels.” says Martin Weik, the leader of a research group at the Institut de Biologie Structurale at the Université Grenoble Alpes.

Weik is one of the primary investigators in a new study that has captured the complex sequence of structural changes, or photocycle, that FAP undergoes in response to light, which drives this fatty acid transformation. Researchers had proposed a possible FAP photocycle, but the fundamental mechanism was not understood, partly because the process is so fast that it’s very difficult to measure. Specifically, scientists didn’t know how long it took FAP to split a fatty acid and release a hydrocarbon molecule.

Experiments at the Linac Coherent Light Source (LCLS) at the Department of Energy’s SLAC National Accelerator Laboratory helped answer many of these outstanding questions. The researchers described their results in Science.

Read more on the SLAC website

Image: A study using SLAC’s LCLS X-ray laser captured how light drives a series of complex structural changes in an enzyme called FAP, which catalyzes the transformation of fatty acids into starting ingredients for solvents and fuels. This drawing captures the starting state of the catalytic reaction. The dark green background represents the protein’s molecular structure. The enzyme’s light-sensing part, called the FAD cofactor, is shown at center right with its three rings absorbing a photon coming from bottom left. A fatty acid at upper left awaits transformation. The amino acid shown at middle left plays an important role in the catalytic cycle, and the red dot near the center is a water molecule.

Credit: Damien Sorigué/Université Aix-Marseille

Researchers capture how materials break apart following an extreme shock

Understanding how materials deform and catastrophically fail when impacted by a powerful shock is crucial in a wide range of fields, including astrophysics, materials science and aerospace engineering. But until recently, the role of voids, or tiny pores, in such a rapid process could not be determined, requiring measurements to be taken at millionths of a billionth of a second.

Now an international research team has used ultrabright X-rays to make the first observations of how these voids evolve and contribute to damage in copper following impact by an extreme shock. The team, including scientists from the University of Miami, the Department of Energy’s SLAC National Accelerator Laboratory and Argonne National Laboratory, Imperial College London and the universities of Oxford and York published their results in Science Advances.

“Whether these materials are in a satellite hit by a micrometeorite, a spacecraft entering the atmosphere at hypersonic speed or a jet engine exploding, they have to fully absorb all that energy without catastrophically failing,” says lead author James Coakley, an assistant professor of mechanical and aerospace engineering at the University of Miami. “We’re trying to understand what happens in a material during this type of extremely rapid failure. This  experiment is the first round of attempting to do that, by looking at how the material compresses and expands during deformation before it eventually breaks apart.”

Read more on the SLAC website

Image: To see how materials respond to intense stress, researchers shocked a copper sample with picosecond laser pulses and used X-ray laser pulses to track the copper’s deformation. They captured how the material’s atomic lattice first compressed and subsequently expanded,, creating pores, or voids, that grew, coalesced, and eventually fractured the material.

Credit: Greg Stewart/SLAC National Accelerator Laboratory

New X-ray laser data system will process a million images a second

When upgrades to the X-ray laser at the Department of Energy’s SLAC National Accelerator Laboratory are complete, the powerful new machine will capture up to 1 terabyte of data per second; that’s a data rate equivalent to streaming about one thousand full-length movies in just a single second, and analyzing every frame of each movie as they zoom past in this super-fast-forward mode.

Data experts at the lab are finding ways to handle this massive amount of information as the Linac Coherent Light Source (LCLS) upgrades come on line over the next several years.

LCLS accelerates electrons to nearly the speed of light to generate extremely bright beams of X-rays. Those X-rays probe a sample such as a protein or a quantum material, and a detector captures a series of images that reveal the atomic motion of the sample in real time. By stringing together these images, chemists, biologists, and materials scientists can create molecular movies of events like how plants absorb sunlight, or how our drugs help fight disease.

Read more on the SLAC website

Image: Data rate comparisons

Credit: Greg Stewart/SLAC National Accelerator Laboratory