Researchers at the SLAC National Accelerator Laboratory are using new instruments at the Linac Coherent Light Source (LCLS) to address scientific questions that were previously out of reach. The LCLS facility, operated by the Department of Energy, has recently undergone a major upgrade known as LCLS-II, which increases its X-ray pulse rate from 120 to up to one million pulses per second.
This upgrade has allowed scientists to enhance existing tools and develop new ones for investigating atomic and molecular phenomena. Two key instruments, qRIXS and chemRIXS, use resonant inelastic X-ray scattering (RIXS) to examine materials in detail. Georgi Dakovski, SLAC lead scientist and qRIXS instrument lead, explained that RIXS measurements are “photon hungry,” with most X-rays absorbed or deflected before reaching detectors. “With the original LCLS pulse rate, capturing just a handful of photons was a work of art. We had to wait a long time to collect enough data for meaningful results,” Dakovski said.
The increased pulse rate now enables researchers to obtain results much faster than before. “The increase has already made an amazing change,” Dakovski said. “Not only is the data coming in faster and with clarity we haven’t seen before, it actually helps us see how the materials are transforming over time. We can watch how energy flows through the material and how the atomic components interact. We can create frame-by-frame ‘movies’ of the dynamic processes. This is only possible due to LCLS’s increased X-ray pulse rate.”
The new qRIXS instrument features a large spectrometer capable of examining materials from multiple angles with high resolution—a capability that required higher photon rates than were previously available at LCLS. Researchers are using qRIXS to study quantum materials such as high-temperature superconductors, aiming for advances in technologies like quantum computing and MRI devices.
Meanwhile, chemRIXS is focused on studying chemical processes in liquid samples. Kristjan Kunnus, SLAC staff scientist and chemRIXS instrument lead, noted improvements: “Previously, we couldn’t investigate low concentration solvates, so we had to use higher concentrations that didn’t completely reflect the chemistry under realistic conditions,” Kunnus said. “Now, we can analyze the diluted samples that matter in chemical applications and still get high-quality data, which just wasn’t possible before.”
Other new tools include MRCO (Multi-Resolution Cookie Box), which uses an array of electron detectors paired with ultrafast laser pulses for precise measurement of electron ejection events in molecules; this helps scientists understand charge transfer on extremely short timescales. Razib Obaid, SLAC staff scientist and MRCO instrument lead stated: “We’re no longer limited by this narrow window we had to look through before… This upgrade broadened the window of what we can study in each experiment.”
The DREAM (Dynamic REAction Microscope) instrument allows detailed imaging of molecules undergoing chemical reactions by focusing intense X-rays on single molecules until they fragment apart—data from millions of these events help reconstruct molecular movies showing reaction dynamics over time.
James Cryan, SLAC senior scientist and TMO instrument lead commented: “How do photochemical processes – like sight, like solar power, like photosynthesis – unfold? How does DNA funnel energy when it absorbs light? How does an electron move from one side of a molecule to another? This tool gives us insight into how these things work at a fundamental level.” He added: “With the original setup, it would have taken years to fully understand a single reaction… Now that DREAM is operating on the upgraded LCLS beamline, we’re getting an entirely new view of these processes. This upgrade marked a turning point – it has made previously impossible research possible.”
The increased volume of data generated at LCLS is also being used for artificial intelligence applications that could improve experimental efficiency and help tune equipment during experiments.
Matthias Kling, director of science and Research & Development at LCLS said: “This integration of AI technology is poised to transform the research landscape, facilitating accelerated scientific discovery.”
LCLS operates as a user facility supported by the DOE Office of Science.
