Breakthrough: X-ray of a single atom captured for the first time

In a remarkable feat, a team of scientists has taken the world’s first X-ray signature of just one atom. This stunning achievement could revolutionize the way scientists detect materials.

The research team was led by Saw Wai Hla, Professor of Physics at Ohio University and scientist at Argonne National Laboratory.

Atoms and the evolution of X-ray technology

Since its discovery by Roentgen in 1895, X-rays have been used in various applications, from medical examinations to security screenings in airports. Even NASA’s Mars rover, Curiosity, is equipped with an X-ray device to examine the materials composition of rocks on Mars.

Over the years, advancements in synchrotron X-ray sources and new instruments have greatly reduced the quantity of materials required for X-ray detection.

However, until now, the smallest amount one could X-ray a sample was in attogram, which is about 10,000 atoms or more. This limitation was due to the extremely weak X-ray signal produced by an atom, making it undetectable by conventional X-ray detectors.

Realizing a long-standing dream

According to Hla, it has been a long-standing dream of scientists to X-ray just one atom, which is now being realized by his research team.

“Atoms can be routinely imaged with scanning probe microscopes, but without X-rays one cannot tell what they are made of. We can now detect exactly the type of a particular atom, one atom-at-a-time, and can simultaneously measure its chemical state,” explained Hla, who is also the director of the Nanoscale and Quantum Phenomena Institute at Ohio University.

“Once we are able to do that, we can trace the materials down to the ultimate limit of just one atom. This will have a great impact on environmental and medical sciences and maybe even find a cure that can have a huge impact for humankind. This discovery will transform the world,” Hla continued.

How to x-ray a single atom

The research team used a purpose-built synchrotron X-ray instrument at the XTIP beamline of Advanced Photon Source and the Center for Nanoscale Materials at Argonne National Laboratory. They chose an iron atom and a terbium atom, both inserted in respective molecular hosts, for demonstration.

To detect the X-ray signal of one atom, the team supplemented conventional detectors in X-rays with a specialized detector made of a sharp metal tip positioned at extreme proximity to the sample to collect X-ray excited electrons. This is a technique known as synchrotron X-ray scanning tunneling microscopy or SX-STM.

“The technique used, and concept proven in this study, broke new ground in X-ray science and nanoscale studies,” said Tolulope Michael Ajayi, the first author of the paper and a Ph.D. student working on this project as part of his thesis.

“More so, using X-rays to detect and characterize individual atoms could revolutionize research and give birth to new technologies in areas such as quantum information and the detection of trace elements in environmental and medical research, to name a few. This achievement also opens the road for advanced materials science instrumentation,” Ajayi concluded.

Decade of collaboration ends with success

Hla has been involved in the development of an SX-STM instrument and its measurement methods for the last 12 years, together with Volker Rose, a scientist at the Advanced Photon Source at Argonne National Laboratory.

“I have been able to successfully supervise four OHIO graduate students for their Ph.D. theses related to SX-STM method development over a 12-year period. We have come a long way to achieve the detection of a single atom X-ray signature,” Hla said.

Investigating environmental effects on rare-Earth atoms

In addition to achieving the X-ray signature of one atom, the team’s key goal was to use this technique to investigate the environmental effect on a single rare-earth atom.

“We have detected the chemical states of individual atoms as well,” Hla explained. “By comparing the chemical states of an iron atom and a terbium atom inside respective molecular hosts, we find that the terbium atom, a rare-earth metal, is rather isolated and does not change its chemical state while the iron atom strongly interacts with its surrounding.”

Rare-earth materials are extremely important in creating and advancing technology, and are used in everyday devices such as cell phones, computers, and televisions.

Through this discovery, scientists can now identify not only the type of element but its chemical state as well, allowing them to better manipulate atoms inside different materials hosts to meet ever-changing needs in various fields.

Connecting synchrotron X-rays with quantum tunneling

Moreover, the research team has also developed a new method called “X-ray excited resonance tunneling or X-ERT” that allows them to detect how orbitals of a single molecule orient on a material surface using synchrotron X-rays.

“This achievement connects synchrotron X-rays with quantum tunneling process to detect X-ray signature of an individual atom and opens many exciting research directions including the research on quantum and spin (magnetic) properties of just one atom using synchrotron X-rays,” Hla excitedly concluded.

Atoms, x-rays and future technology

In summary, the incredible feat of capturing the first-ever X-ray signature of a single atom marks a significant milestone in the field of X-ray science and nanoscale studies.

This achievement, made possible by the dedicated efforts of a collaborative research team led by Professor Saw Wai Hla, opens up a world of possibilities for scientific research and technological advancements.

By pushing the boundaries of what was previously thought to be undetectable, this innovative technique has the potential to revolutionize various fields, from environmental and medical sciences to quantum information and advanced materials science instrumentation.

As scientists continue to explore the capabilities of this powerful tool, they pave the way for discoveries that could have a profound impact on our understanding of the world at the atomic level and beyond.

The full study was published in the journal Nature.

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