A team of Ohio University, Argonne National Laboratory, University of Illinois-Chicago and others, led by So Wai Hla, Ohio University physics professor and Argonne National Laboratory scientist, has produced the world’s first X-ray SIGNAL consisting of a single atom. According to Phys.org, this groundbreaking achievement could revolutionize the way scientists detect materials.

Since Röntgen’s discovery in 1895, X-rays have been used in everything from medical examinations to airport security checks. Even NASA’s rover Curiosity is equipped with an X-ray instrument to study the material composition of rocks on Mars. An important use of X-rays in science is to determine the type of materials in a sample. Over the years, the amount of material in a sample required for X-ray detection has been greatly reduced with the development of synchrotron X-ray sources and new instruments. To date, the smallest amount that can be X-rayed in a sample is in the attogram, that is, about 10,000 atoms or more. This is because the X-ray signal generated by the atom is extremely weak, so conventional X-ray detectors cannot be used to detect it. According to Hla,

“Atoms can routinely be imaged with scanning probe microscopes, but without X-rays it’s impossible to tell what they’re made of. We can now pinpoint the type of a particular atom, one atom at a time,” said Hla, director of the Ohio State Institute for Nanoscale and Quantum Phenomena. “Once we can do that, we’ll be able to trace materials to the ultimate limit of just one atom.” This will have a huge impact on the environmental and medical sciences and may even lead to treatments that could have a huge impact on humanity. discovery will change the world.”

In articles published in a scientific journal Nature Published on the cover of the print edition of the scientific journal dated May 31, 2023 and dated June 1, 2023, Hla and among them Ph.D. Students in Ohio used a custom-built synchrotron X-ray instrument on the XTIP Advanced Photon Source beamline and at Argonne National Laboratory’s Center for Nanoscale Materials.

For the demonstration, the team chose an iron atom and a terbium atom, both embedded in their respective molecular hosts. To detect the X-ray signal of a single atom, the research team supplemented conventional X-ray detectors with a special detector made of a sharp metal tip placed very close to the sample to collect the electrons excited by the X-rays. a synchrotron X-ray scanning tunneling microscope or SX-STM. X-ray spectroscopy in the SX-STM is triggered by the photoabsorption of electrons at the core level, which creates fundamental fingerprints and effectively identifies the underlying material type.

According to Hla, spectra are like fingerprints, each unique and able to identify exactly what it is.

“The technique and validated concept used in this study breaks new ground in X-ray science and nanoscale research,” said Tolulope Michael Ajayi, first author of the paper and who did this work as part of his PhD. thesis. “Furthermore, using X-rays to detect and characterize single atoms could revolutionize research and lead to new technologies in environmental and medical research in areas such as quantum information and trace element detection. This achievement also paves the way for advanced tools for materials science.”

Hla has been involved with Argonne National Laboratory Advanced Photon Source scientist Volker Rose in the development of the SX-STM instrument and measurement techniques for the past 12 years.

“I was able to successfully supervise four Ohio State graduate students for their doctoral theses on the development of the SX-STM method over a 12-year period. “We’ve come a long way in enabling the detection of a monoatomic X-ray trace,” said Hla.

Hla’s research focuses on the nano- and quantum sciences, with a special emphasis on understanding the chemical and physical properties of materials at a fundamental, single-atom basis. Besides obtaining the X-ray signature of a single atom, one of the team’s main goals was to use this technique to study the effect of the environment on a single atom of a rare earth metal.

“We also discovered the chemical states of individual atoms,” Hla explained. “By comparing the chemical states of the iron atom and the terbium atom within their respective molecular hosts, we found that the terbium atom, a rare earth metal, is highly isolated, and that the iron atom does not change its chemical state while interacting strongly with its environment.”

Many rare earth materials used in everyday devices such as cell phones, computers and televisions are extremely important to the creation and development of technology. With this discovery, scientists can now determine not only the type of element but also its chemical state, allowing them to better manipulate atoms in different host materials to meet ever-changing needs in different fields. Additionally, they developed a new method called X-ray excited resonance tunneling, or X-ERT; this allows them to detect how single-molecule orbitals are oriented on a material’s surface using synchrotron X-rays.