title: Direct observation of X-ray induced atomic motion using scanning tunneling microscope combined with synchrotron radiation.
abstract: X-ray induced atomic motion on a Ge(111)-c(2 x 8) clean surface at room temperature was directly observed with atomic resolution using a synchrotron radiation (SR)-based scanning tunneling microscope (STM) system under ultra high vacuum condition. The atomic motion was visualized as a tracking image by developing a method to merge the STM images before and after X-ray irradiation. Using the tracking image, the atomic mobility was found to be strongly affected by defects on the surface, but was not dependent on the incident X-ray energy, although it was clearly dependent on the photon density. The atomic motion can be attributed to surface diffusion, which might not be due to core-excitation accompanied with electronic transition, but a thermal effect by X-ray irradiation. The crystal surface structure was possible to break even at a lower photon density than the conventionally known barrier. These results can alert X-ray studies in the near future about sample damage during measurements, while suggesting the possibility of new applications. Also the obtained results show a new availability of the in-situ SR-STM system.
authors.affiliation: Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Saito
authors.forename: Takehiro
authors.initials: T
authors.lastname: Tanaka
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Takagi
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Hosokawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Notsu
authors.forename: Gozo
authors.initials: G
authors.lastname: Ohzeki
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Kohmura
authors.forename: Megumi
authors.initials: M
authors.lastname: Akai-Kasaya
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kuwahara
authors.forename: Seishi
authors.initials: S
authors.lastname: Kikuta
authors.forename: Masakazu
authors.initials: M
authors.lastname: Aono
mesh_terms: D004579:Electron Transport / Q000528:radiation effects; D005857:Germanium / Q000737:chemistry* / Q000528:radiation effects*; D008422:Materials Testing; D016252:Microscopy, Scanning Tunneling / Q000379:methods*; D009038:Motion; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects*; D017356:Synchrotrons; D014965:X-Rays
chemical_list: D005857:Germanium