image: Beamline I20-scanning at the Diamond Light source, one of the most powerful and best equipped beamlines for high-resolution spectroscopy in the world, where the discovery was made.
Credit: University of Melbourne
Hidden features uncovered in X-ray signals are set to overturn a key scientific theory and fundamentally change how X-rays are interpreted across fields of physics, chemistry, biology and materials science, new research reveals.
Researchers say the discovery can help scientists measure X-rays more precisely and reliably, and improve our understanding of common materials, from battery materials to biological proteins.
X-ray science focuses on the unique energy signatures of atoms. These include the specific X-rays emitted when electrons transition into inner shells – the strongest of which are known as K-alpha lines – as well as distinct energy thresholds at which atoms begin to strongly absorb X-rays.
For more than 50 years, the entire field has relied on the assumption that a core parameter in the equation used to model X-ray absorption spectra, known as the standard XAFS equation, is fixed and does not change.
That foundation just shifted thanks to a novel discovery made by a team led by University of Melbourne Professor Chris Chantler from the School of Physics.
“Our experimental findings show that this fundamental rule is anything but constant. We discovered what are essentially ‘Hidden Satellites’ previously buried in the background of energy signatures emitted from manganese metal,” Professor Chantler said.
“These satellite features are not static – they evolve with increasing incident photon energy. It changes everything we thought we knew about the baseline of X-ray interaction,” he said.
The research has been published in Nature Scientific Reports.
Using relativistic quantum mechanics, the researchers revealed subtle, hidden patterns within K-alpha X-ray spectra. They explained that these features define their onset and evolve dynamically as the energy of incoming X-rays changes, dramatically altering how materials absorb X-rays.
“We’ve found that the many body reduction factor is actually a function of energy,” study first author University of Melbourne Ramesh Rijal explained.
“We developed a high resolution, high-accuracy technique now known as XR-HERFD, which we implemented at the the Diamond Light Source, the largest synchrotron in the UK. This revealed that surprisingly up to 25 per cent of the total signal was created by these new processes,” he said.
“It’s like discovering a ghost in the machine that has been there all along, skewing our data and theory.
“This discovery doesn’t just impact fundamental physics – it offers a new ‘ruler’ for any scientist using synchrotrons to study the building blocks of our world. By accounting for these hidden features, researchers can now achieve a level of precision and understanding in their measurements that was previously thought impossible.”
The findings are the most accurate measurement of the relativistic quantum evolution, say the researchers. They challenge the foundation of the more than 10,000 research papers published every year relying on this technique.
The team used XR-HERFD (eXtended-Range High-Energy-Resolution Fluorescence Detection) combined with Principal Component Analysis (PCA) to isolate the ‘satellites’. The results reached a statistical significance of 270 standard errors far exceeding the standard threshold for scientific discovery.
Journal
Scientific Reports