Revolutionary X-ray laser technology enables scientists to capture atomic-scale processes occurring in quadrillionths of a second
Imagine trying to photograph a hummingbird's wings in perfect detail without any blur. Now, shrink that challenge down to the atomic scale, where molecular bonds vibrate in quadrillionths of a second, and you begin to grasp the extraordinary challenge facing scientists studying the nanoscale world. These ultrafast processes are the foundation of everything - from how plants convert sunlight into chemical energy to how our electronic devices store and process information.
For decades, these phenomena occurred in a blind spot for science, too fast to capture and too small to see with conventional tools. This scientific frontier is now being illuminated by an extraordinary machine in the Swiss countryside: the SwissFEL X-ray Free-Electron Laser.
By producing flashes of X-ray light lasting just femtoseconds (that's 0.000000000000001 seconds), SwissFEL is enabling researchers to create atomic-scale movies of processes once considered too fast and too small to observe directly, opening unprecedented opportunities to understand and ultimately control the fundamental workings of nature 2 3 .
1 femtosecond = 0.000000000000001 seconds - the natural timescale of atomic vibrations and electron movements.
Resolving details as small as 0.1 nanometers - the scale of individual atoms and chemical bonds.
The Swiss Free-Electron Laser (SwissFEL) represents a revolutionary class of scientific instrument that combines the best attributes of different light sources while overcoming their limitations. Conventional lasers can produce incredibly short pulses but their relatively long wavelengths cannot resolve atomic-scale details. Synchrotron light sources (like Swiss Light Source) can reveal fine structural details but their light pulses aren't short enough to capture the fastest atomic and molecular motions.
SwissFEL shatters these constraints by generating ultra-bright, ultra-short pulses of hard X-rays that can resolve atoms while capturing motions occurring in femtoseconds - approximately the duration of a molecular vibration 2 .
Facility Length
Pulse Duration
Spatial Resolution
The facility operates two parallel beamlines: Aramis for hard X-rays (1.77-12.4 keV) and Athos for soft X-rays (240-1930 eV), each tailored for different scientific applications 4 .
The femtosecond timescale is particularly significant because it represents the natural cadence of the molecular and atomic world. Chemical bonds form and break on this timescale, electrons rearrange during chemical reactions, and energy transfers occur within and between molecules. By having a camera with a "shutter speed" matching these processes, researchers can now freeze these motions for detailed study rather than inferring what happened from before-and-after snapshots 4 .
| Light Source Type | Time Resolution | Spatial Resolution | Key Strengths |
|---|---|---|---|
| SwissFEL | 1-60 femtoseconds | Atomic (~0.1 nanometer) | Captures both structure and dynamics at atomic scale |
| Synchrotron Sources | ~100 picoseconds (100,000 fs) | Atomic (~0.1 nanometer) | Excellent for determining static structures |
| Conventional Lasers | Femtoseconds | Limited by wavelength (~100+ nanometers) | Excellent time resolution for electronic processes |
Table 1: Key Capabilities of SwissFEL Compared to Other Light Sources
Quantum materials represent one of the most exciting frontiers in physics, exhibiting exotic properties like high-temperature superconductivity, unconventional magnetism, and unusual electronic behaviors. Understanding these materials is not just academically fascinating - it holds potential for transformative technologies in computing, energy, and electronics.
"The ability to observe the atomic world in real-time, at its natural speed, represents a transformative achievement in science."
A recent groundbreaking experiment at SwissFEL illustrates this potential beautifully. Researchers studied a quantum material called lanthanum strontium manganite (La₀.₅Sr₁.₅MnO₄), which exhibits a property known as "orbital ordering" - a specific, organized pattern in how electrons arrange themselves around atoms. This ordering profoundly influences the material's electronic and magnetic behavior. Using the Bernina experimental station at SwissFEL, the team employed an advanced technique called time-resolved X-ray surface diffraction to observe what happens when this material is excited by a conventional laser pulse 8 .
The results challenged long-held assumptions. Rather than the entire material responding uniformly to light, the surface layers lost their orbital order much faster than the inner bulk regions. The surface disorder occurred through local distortions - irregular atomic movements - while the inner layers remained stable longer. This discovery that surfaces and interiors respond differently to excitation has profound implications for designing future electronic and quantum devices, where surfaces and interfaces often dominate device behavior 8 .
| Tool or Technique | Function in Research | Scientific Application |
|---|---|---|
| Femtosecond X-ray Pulses | Acts as an ultra-fast flash to freeze atomic motion | Probing structural changes during chemical reactions and material transformations |
| Optical Laser Systems | Initiates processes in samples (pump) | Exciting electrons, triggering reactions, launching vibrations |
| X-ray Emission Spectroscopy | Measures electronic structure changes | Tracking how energy flows and distributes in molecules and materials |
| Serial Femtosecond Crystallography | Determines structures from tiny crystals | Studying proteins and complex materials without large single crystals |
| Electron-Beam Lithography | Creates nanoscale sample structures | Fabricating artificial spin ice and other model magnetic systems |
| Kirkpatrick-Baez Mirrors | Focuses X-rays to micron scale | Concentrating X-ray beams on tiny samples for detailed analysis |
Table 2: Essential Research Tools for Ultrafast Nanoscience at SwissFEL
The biological sciences are undergoing their own revolution thanks to SwissFEL's capabilities. Using a technique called serial femtosecond crystallography, researchers can determine the structures of vital biological molecules and proteins. This is crucial for understanding fundamental life processes and developing new pharmaceuticals. The technique works by flowing a stream of tiny protein crystals across the X-ray beam, collecting diffraction patterns from each crystal before the powerful X-rays destroy them. These "snapshots" are then combined to reconstruct the full three-dimensional structure of the protein 4 .
SwissFEL enables researchers to study protein dynamics, enzyme mechanisms, and molecular interactions in real-time.
Understanding protein structures at atomic resolution accelerates drug discovery and development processes.
Recent research at SwissFEL has demonstrated both the power and necessary cautions of these approaches. A study on bacteriorhodopsin, a light-driven proton pump, examined how using different laser power densities to activate the protein affects the resulting structural models. At very high power densities, researchers observed significant changes in the conformation of the protein's retinal component and increased heating of functionally critical regions. This highlights the importance of carefully controlling experimental conditions even as we push the boundaries of what we can observe 7 .
The quantum materials experiment that revealed different surface and bulk dynamics provides an excellent case study in how SwissFEL enables new science. Here's how the researchers accomplished this:
Researchers prepared high-quality crystals of the layered manganese oxide quantum material La₀.₅Sr₁.₅MnO₄, which exhibits strong orbital ordering 8 .
A precisely controlled laser pulse hit the sample surface, depositing energy and initiating changes in the orbital order. This served as "time zero" for the experiment 8 .
At carefully controlled time delays after the laser excitation (from femtoseconds to picoseconds), an ultra-short X-ray pulse from SwissFEL struck the same spot on the sample 8 .
By carefully adjusting the scattering geometry, the researchers could separate the X-ray diffraction signal coming from the surface atoms from that of the bulk material - a technical achievement previously not possible 8 .
Advanced detectors recorded the diffraction patterns at each time delay, effectively creating a frame-by-frame movie of how both the surface and bulk atomic structure evolved after the initial excitation 8 .
The analysis revealed that the surface of the material lost its orbital order significantly faster than the bulk. This non-uniform response was driven by local distortions at the surface that propagated unevenly through the material. The findings challenge earlier models that assumed photoinduced phase transitions occur uniformly throughout a material and highlight the critical importance of surface and interface effects in quantum materials 8 .
Relative speed of orbital order disruption after laser excitation
This discovery isn't just academically interesting - it provides crucial guidance for designing future materials and devices. In the race toward smaller, faster electronics and quantum technologies, where surface-to-volume ratios continually increase, understanding and ultimately controlling these surface-specific dynamics may enable new approaches to ultrafast switching and information processing.
| Research Field | Key Application | Potential Impact |
|---|---|---|
| Chemistry | Mapping reaction pathways and intermediates | Designing more efficient chemical processes and catalysts |
| Biology | Determining structures of membrane proteins and enzymes | Developing new pharmaceuticals and understanding disease mechanisms |
| Materials Science | Observing phase transitions and defect dynamics | Creating new materials for electronics, energy storage, and quantum computing |
| Nanotechnology | Studying energy transfer in nanoscale structures | Developing more efficient nanodevices and sensors |
| Quantum Materials | Tracking electronic and magnetic ordering dynamics | Engineering materials for quantum information technologies |
Table 3: Representative Scientific Applications of SwissFEL Across Disciplines
As SwissFEL continues operations, its technological capabilities keep advancing. The facility is developing even more sophisticated operation modes, including the ability to produce attosecond pulses (thousand times shorter than femtoseconds), two-color pulse sequences for probing multiple time scales simultaneously, and advanced polarization control to study magnetic materials with unprecedented precision 4 .
The next frontier: pulses a thousand times shorter than femtoseconds, enabling direct observation of electron dynamics.
The ongoing integration of SwissFEL with other cutting-edge facilities at the Paul Scherrer Institute creates a unique research ecosystem.
These developments will open even more scientific frontiers, potentially allowing researchers to directly observe electron dynamics and quantum phenomena that are currently only theoretical predictions.
The ongoing integration of SwissFEL with other cutting-edge facilities at the Paul Scherrer Institute - including the Swiss Light Source (currently being upgraded to SLS 2.0) 7 - creates a unique research ecosystem where scientists can combine multiple techniques to tackle increasingly complex scientific questions. This synergistic approach promises to accelerate discoveries across fields from fundamental physics to applied technology development.
The ability to observe the atomic world in real-time, at its natural speed, represents a transformative achievement in science. SwissFEL and similar X-ray free-electron lasers worldwide are providing this capability, enabling researchers across disciplines to address questions that were once considered unanswerable. From revealing the intricate atomic dances behind chemical reactions to exposing the hidden dynamics of quantum materials and biological molecules, these extraordinary instruments are deepening our fundamental understanding of nature while simultaneously accelerating the development of new technologies that will shape our future. As these facilities continue to evolve and their capabilities expand, we stand at the threshold of discoveries we cannot yet imagine, all made possible by our newfound ability to see the previously unseeable.