AVS 52nd International Symposium
    Applied Surface Science Monday Sessions
       Session AS+BI+NS-MoM

Paper AS+BI+NS-MoM11
Scanning Tunneling Microscope Assisted with Inner-Shell Excitation by Hard X-ray Micro-Beam

Monday, October 31, 2005, 11:40 am, Room 206

Session: Nanoscale Analysis: Biomaterial and Other Applications
Presenter: A. Saito, Riken Harima Inst., Japan
Authors: A. Saito, Riken Harima Inst., Japan
J. Maruyama, Osaka Univ., Japan
K. Manabe, Osaka Univ., Japan
K. Kitamoto, Riken Harima Inst., Japan
K. Takahashi, Osaka Univ., Japan
Y. Tanaka, Riken Harima Inst., Japan
M. Yabashi, Japan Synchrotron Radiation Res. Inst.
M. Ishii, Japan Synchrotron Radiation Res. Inst.
M. Akai-Kasaya, Osaka Univ., Japan
S. Shin, Riken Harima Inst., Japan
T. Ishikawa, Riken Harima Inst., Japan
Y. Kuwahara, Osaka Univ., Japan
M. Aono, Osaka Univ., Japan
Correspondent: Click to Email
A scanning tunneling microscope (STM) system was developed for in-situ experiments under the irradiation of highly brilliant hard x-rays of synchrotron radiation (SR). It appears attractive to excite the core electrons of specific level under the STM observation, because it may enable to analyze the elements or control the local reaction with the spatial resolution of STM. To surmount a small probability of the core-excitation by hard X-rays, SR of the highest brilliance at the SPring-8 was used. To prevail the difficulties produced by the highly brilliant SR (damage around the STM scanner, thermal and electrical noise, and instability of the system such as thermal drift), the beam size was limited to @phi@10 µm. The small beam size serves also to obtain a high signal to noise ratio and high spatial resolution by restraining the electrons emitted from a wide area. The in-situ STM observation was enabled by developing an accurate "three-body (invisible micro-beam, tip-end, and sample surface)" alignment system in ultrahigh vacuum. Despite a noisy condition of SR facility and radiation load around the probe tip, STM images were successfully obtained with atomic resolution. The analysis of the clean Si(111) surface revealed that the thermal expansion affects to the behavior of the tip much strongly than reported in the past reports. Next, the tip-current spectra were obtained on Ge nano-islands on the clean Si(111) surface, by changing the incident photon energy across the Ge absorption edge. A current modification was detected at the absorption edge, with a spatial resolution of the order of 10 nm. This system will serve to observation or manipulation with atomic resolution, which is based on the interaction between the surface atoms and the hard X-ray photons.