HREELS STUDY ON HYDROGEN ADSORBED AL(111) SURFACE

Recently we have confirmed that aluminium hydride desorbs around room temperature from hydrogen adsorbed Al(111) surface by thermal desorption spectroscopy (TDS). In this study, adsorbed states of hydrogen atoms on Al(111) were investigated, from 85 K to the desorption temperature, by use of high resolution electron energy loss spectroscopy (HREELS). The loss features observed in the HREEL spectra were assigned based on the local density functional (LDF) calculation. It was revealed that two or three hydrogen atoms adsorb on an aluminium terminal site at low temperature (< 150 K), and that some fraction of the terminal hydrogen atoms migrate to bridge sites on increasing the temperature above 150 K.