We have identified the monohydride Si(001)-(2X 1):H surface and the dihydride Si(001)-(1X1)::2H surface by angle-resolved electron-energy-loss spectroscopy and elastic lowenergy electron diffraction. On the monohydride (2X1):H surface the S3 transition from the back-bond surface state was distinctly observed although the Sl transition from the dangling-bond surface state disappeared, while on the dihydride (1X1)::2Hsurface both the S3 and the Sl transitions completely disappeared. These facts show that on the monohydride surface the subsurface strain due to dimerization remains; on the other hand, on the dihydride surface the strain is healed out. The hydrogen-induced transitions for the two surfaces were clearly distinguished; the transition energy for the (2X 1):H surface (SHl) was 8.0 eV and that for the (1 X 1)::2H surface (SHq) increased from 7.0 to 7.5 eV with increas-ing~k~~~due to dispersion. The present results support and develop the models for the monohydride and the dihydride surfaces proposed by Sakurai and Hagstrum.

To date, various connection rerouting methods for connection-oriented mobile networks have been proposed. The previous methods, however, are limited to specific topologies or environments. In this paper, we propose the connection-information-based rerouting widely applicable to various connection-oriented mobile networks. This method requires neither a specific topology nor a complex connection, enables fast rerouting, provides appropriate route optimality, and can be extended easily.

Inelastic low-energy-electron-diffraction measurements on a clean Si(001)-2×1 surface were made. Surface cleanliness was verified by Auger analysis. The elastic and inelastic energy intensity profiles of the (00) spot were measured to select incident conditions amenable to a kinematic analysis of the energy loss profiles. The surface-plasmon dispersion relation for Si(001)-2×1 surface was derived from the inelastic data using a conservation-law model. The dispesion curve decreases as the momentum parallel to the surface increases.

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