RELATION BETWEEN SURFACE ELECTRONIC STATES AND SURFACE PLASMON DISPERSION

点击翻译按钮获取中文摘要

(1) We mada a combined measurement system with a high-resolution electron-energy-loss spectroscopy (HREELS) and a scanning tunnel microscope (STM) ; HREELS-STM.The resolution of the HREELS is 1meV.(2) The surface plasmon energy and dispersion are measured on the silver (111) and (110) surfaces. The plasmon energy at q=0 is observed at 3.69 meV.The dispersion on the (111) surface is quadratic. On the other hand, the dispersion on the (110) surface has anisotropy between [100] and [110] directions. But the measured energy at finite q is scattered with the accuracy of tenths of meV,so that the dispersion curves are not determined correctly.(3) In order to understand the scattering of the measured surface plasmon energy at finite q, we observed the surface morphology by STM.The surfaces are well ordered with steps. The distances are between 5 nm and 60 nm. This step may influence the dispersion at shorter momentum transfer than 0.002 nm^<-1>. The distribution of the steps don't contribute to the scattered surface plasmon dispersion.