Scanning tunneling microscopy combined with hard X-ray microbeam of high brilliance from synchrotron radiation source

In situ scanning tunneling microscopy (STM) with highly brilliant hard X-ray irradiation was enabled at SPring-8. To obtain a good signal-to-noise ratio for elemental analysis, an X-ray beam with a limited size of phi 10 mu m was aligned to a specially designed STM stage in ultrahigh vacuum. Despite various types of noises and a large radiation load around the STM probe, STM images Were Successfully observed with atomic resolution. The use of a new system for elemental analysis was also attempted, which was based oil the modulation of tunneling signals rather than emitted electrons. Among tunneling signals, tunneling current was found to be better than tip height as a signal to be recorded, because the former reduces markedly the error of measurement. Oil a Ge nanoisland oil a clean Si(111) surface, the modulation Of tunneling current was achieved by changing the incident photon energy across the Ge absorption edge.