The surface structure of ZrB 2 (0001) was investigated using coaxial impact-collision ion scattering spectroscopy (CAICISS). The ZrB 2 (0001) 1 Â 1 surface was prepared by HF solution treatment and annealing in vacuum. It was directly evidenced that the ZrB 2 (0001) surface is terminated with a Zr layer. Moreover, we found that the interlayer spacing between the first Zr layer and the second B layer is expanded by 20% with regard to c-axis lattice constant. Since small amount of O atoms were detected after the cleaning, the incorporation of the residual O atoms into the subsurface region of the ZrB 2 (0001) surface is likely to be the origin of the large expansion.

A synchrotron-radiation-based neV-resolution spectrometer has been developed using single-line pure nuclear Bragg reflection. The developed optical system consists of two components: a 57 FeBO 3 single crystal near the Néel temperature for producing 57 Fe Mössbauer radiation from synchrotron radiation, and a single-line Mössbauer absorber ( 57 Fe-enriched stainless steel foil) for analyzing the energy distribution. As a feasibility study, we have performed the measurement of the Mössbauer radiation diffracted by a Si crystal under ultrasound vibration with the optical system and have successfully observed the neVrange energy modulation due to the ultrasound vibration.

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