Events
Events at Physics |
Events on Friday, November 13th, 2026
- Physics Department Colloquium
- X-rays Meet Quantum Tunneling: A Journey to Single-Atom Spectroscopy
- Time: 3:30 pm - 4:30 pm
- Place: Chamberlin 2241 -
- Speaker: Volker Rose, Argonne National Laboratory
- Abstract: How do we identify a single atom using X-rays? This colloquium will explore the fundamental physics of X-rays and their interaction with matter, leading to the ability to investigate individual atoms through X-ray spectroscopy. Beginning with an introduction to X-ray generation, synchrotron radiation, and conventional X-ray microscopy, we will explore how X-rays reveal the structure, chemistry, and physical properties of materials. I will then share the scientific journey of developing Synchrotron X-ray Scanning Tunneling Microscopy (SX-STM), a technique that my team and I have pursued over much of my professional career. By combining the elemental, chemical, and magnetic sensitivity of synchrotron X-rays with the atomic-scale spatial resolution of scanning tunneling microscopy, SX-STM extends X-ray spectroscopy beyond the spatial resolution limits of conventional X-ray microscopy. Through the detection of X-ray-excited tunneling currents, we have achieved X-ray spectroscopic characterization of individual atoms, enabling the determination of their elemental identities and local chemical states. I will discuss the experimental challenges and breakthroughs that made these measurements possible, followed by recent advances in studying chemically complex materials, resolving magnetism at the atomic-layer level, and exploring the magnetic properties of individual atoms. The underlying concepts, light-matter interactions, quantum tunneling, and magnetism, connect to fundamental questions across physics. The goal of this colloquium is to make these ideas accessible to a broad audience while illustrating how scientific curiosity and experimental innovation can push the boundaries of what we can measure. This work was performed at the Advanced Photon Source and the Center for Nanoscale Materials, U.S. Department of Energy Office of Science User Facilities, under Contract No. DE-AC02-06CH11357. [1] Nature 618, 69–73 (2023). [2] Advanced Materials 36, 2402442 (2024). [3] Physical Review Materials 10, L091401 (2026).
- Host: Ke Fang