Field Ion Scanning Tunneling Microscopy and Its Application to Oxygen Adsorption on the Ag(110) 1x1 Surface

A field ion-scanning tunneling microscope (FI-STM), a combination of a scanning tunneling microscope (STM) and a field ion microscope (FIM), was constructed with successful performance. It was applied to the investigation of the oxygen adsorption on the Ag(110) surface. The FI-STM results show that atomic oxygen is mobile on the Ag surface at room temperature until it finds two free mobile Ag atoms to form an Ag-O-Ag linear chain along the 〈001〉 direction. Our FI-STM data suggest that, in addition to this type of atomic oxygen adsorption, there is another type of oxygen adsorption over the Ag-O-Ag linear chains with much weaker bonding to the Ag substrate. The type of weakly bonded atomic oxygen may play an important role in the partial oxidation of ethylene.