THE INTERACTION OF AL AND O ATOMS ON W(110) STUDIED WITH METASTABLE IMPACT ELECTRON-SPECTROSCOPY (MIES) AND UPS

Al layers (< 2.5 adlayers thickness) are grown on W(110) under the ''i n situ'' control of metastable impact electron spectroscopy (MIES) and photoelectron spectroscopy (UPS). The adlayer thickness was determine d by combining LEED and work function measurements. The interaction of oxygen with the Al adlayers is studied. In order to analyze the adsor bed-oxygen/oxide transition, thin layers of alumina are grown by coads orbing Al and oxygen on a 750 K hot W(110) surface. The resulting MIE and UP spectra are compared with those obtained during the oxygenation of the Al layers. Finally, the MIE spectra for Al/W, Al/W + O-2 and a lumina are simulated by taking into account information on the electro nic structure available from previous studies.