In a groundbreaking achievement, a team of scientists led by Professor Saw Wai Hla from Ohio University and Argonne National Laboratory has successfully captured the X-ray signature of a single atom. This remarkable feat, funded by the U.S. Department of Energy, Office of Basic Energy Sciences, has the potential to revolutionize material detection methods. [1]

Figure 1. Single atom X-ray mechanism

Figure 1 shows When X-rays (blue color) illuminate onto an iron atom (red ball at the center of the molecule), core level electrons are excited. X-ray excited electrons are then tunnel to the detector tip (gray) via overlapping atomic/molecular orbitals, which provide elemental and chemical information of the iron atom. Since their discovery by Roentgen in 1895, X-rays have been widely utilized in various fields, ranging from medical diagnostics to security screenings. Scientists have continuously improved X-ray detection techniques, reducing the required sample size to as little as 10,000 atoms or more. However, the extremely weak X-ray signals emitted by individual atoms have posed a significant challenge, preventing their direct detection. Professor Hla and his research team have now realized the long-standing dream of X-raying a single atom. [1]

By using 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, the scientists were able to achieve this breakthrough. Their approach involved supplementing conventional X-ray detectors with a specialized detector made of a sharp metal tip positioned in close proximity to the sample, employing a technique known as synchrotron X-ray scanning tunneling microscopy (SX-STM). This method, called X-ray spectroscopy in SX-STM, relies on the photoabsorption of core level electrons to identify the elemental type of the materials, providing unique "fingerprints" for each atom. [1]

The implications of this achievement are immense. By detecting and characterizing individual atoms using X-rays, researchers can gain valuable insights into their chemical states. This advancement holds great promise for environmental and medical sciences, and may even contribute to groundbreaking discoveries, such as finding cures for various diseases. The ability to trace materials down to a single atom level will have a transformative impact on numerous scientific disciplines. [1]

Professor Hla's study focuses on nano and quantum sciences, with a particular emphasis on understanding the fundamental properties of materials at the atomic level. In addition to successfully capturing the X-ray signature of a single atom, the team also aimed to investigate the environmental effects on rare-earth atoms. By comparing the chemical states of iron and terbium atoms inside molecular hosts, they observed that terbium atoms, being rare-earth metals, tend to remain isolated and retain their chemical states, whereas iron atoms interact more strongly with their surroundings. [1]

This breakthrough not only enables the identification of elemental types but also provides insights into the chemical states of atoms within different materials. Such knowledge empowers scientists to manipulate atoms more effectively, catering to the ever-evolving needs of various fields, including technology advancements. Additionally, the researchers developed a novel method called "X-ray excited resonance tunneling" (X-ERT), which allows them to study the orientation of individual molecule orbitals on material surfaces using synchrotron X-rays. [1]

The team, comprising researchers from Ohio University, Argonne National Laboratory, and the University of Illinois-Chicago, including several graduate students, has paved the way for exciting future research directions. They aim to explore the quantum and spin (magnetic) properties of individual atoms using synchrotron X-rays, further expanding the applications of this technology. With the support of Professor Hla and his dedicated research team, X-rays are poised to revolutionize critical materials research and drive scientific advancements in the years to come. [1]

Source: Ohio University

References:

1. https://www.ohio.edu/news/2023/05/scientists-report-worlds-first-x-ray-single-atom-nature

Cite this article:

Hana M (2023), Scientists Capture the Unseen - World's First X-ray Image of a Single Atom, AnaTechmaz, pp.454