At the Photon Factory, KEK, Japan, Dr. T. Okuda (University of Tokyo) and his colleagues have developed a new technique for determining the identity of groups of individual atoms. Scanning tunneling microscopy (STM) is an existing powerful characterization method, which can detect the atomic positions in real space. In order to upgrade the STM by giving it the capability to distinguish chemical species, the research group employed synchrotron X-rays, which excite core-level electrons in the sample's atoms. In this way, secondary electrons can be detected by the STM as they tunnel across the gap. The important point here is that the tunneling current depends on the chemical species. Accordingly, the technique provides chemical imaging. The current spatial resolution is around 10 nm. In the present research, Fe and Ni L absorption edges were chosen to control the core-level excitation. The beamline used was BL-13C. For more information, see the paper, "Nanoscale Chemical Imaging by Scanning Tunneling Microscopy Assisted by Synchrotron Radiation", T. Okuda et al., Phys. Rev. Lett. 102, 105503 (2009)
