Atomic-level images emerged in the mid-1950s and have been developing rapidly since then. In 2008, physicists successfully used an electron microscope to image a single hydrogen atom. Five years later, scientists were able to look inside a hydrogen atom using a “quantum microscope”, which led to the first direct observation of electron orbitals. And now we have the first X-ray image of a single atom taken by scientists at Ohio State University, Argonne National Laboratory and the University of Illinois at Chicago.

what is known

To date, the smallest number of atoms that can be scanned using X-rays is about 10,000. This is because the X-ray signal produced by an atom is extremely weak. Atoms can be visualized with scanning probe microscopes, but without X-rays it’s impossible to tell what they’re made of.

Therefore, the latest discovery, in which it is possible to accurately determine the type of a particular atom and simultaneously measure its chemical state, is considered a breakthrough. Understanding the chemical state of individual atoms will allow us to better manipulate them within different materials.

Image of a ring-shaped molecule and X-ray signature of a single Fe atom / Photo Ohio University

This will have major implications for quantum information, materials science, environmental and medical sciences, and could even lead to world-changing drugs.
– Says So Wai Hla, head of the study, who has been working on the technology for 12 years.

The authors used a custom-built XTIP Advanced Photon Source synchrotron X-ray instrument. For the demonstration, the team chose an iron atom and a terbium atom inside the molecules.

A special detector was added to conventional X-ray detectors to collect electrons excited by X-ray radiation. X-ray spectroscopy is triggered by photoabsorption of ground-level electrons that leave traces of atoms. To Hla, spectra are like fingerprints, each unique and able to show exactly what kind of atom is in front of us.