Surface structure analysis using low energy scattered and recoiling ions

Abstract

There have been many studies of surface structure and adsorption using low energy ion scattering (LEIS). A well quoted example is the study of oxygen adsorption on the Ni(110) surface, but despite the numerous studies there is not yet agreement on the adsorption site. It is evident that LEIS alone cannot yield enough information to differentiate between some of the proposed models and LEED does not provide the necessary complementary information required to distinguish between similar models. In a new study additional information has been gathered by combining the results of LEIS with low energy hydrogen scattering and low energy negative ion recoil spectroscopy. The hydrogen scattering experiments yield similar information to its medium energy and high energy (RBS) analogues by the processes of channeling and blocking to locate the adsorption site relative to the underlying atoms. The low energy negative ion recoil process is extremely sensitive to the electronegative atoms and is thus a perfectly tailored tool for oxygen studies. The angular distributions of the negative ions yield valuable information concerning its initial physical adsorption site. These three aspects of low energy ion bombardment have been applied to the Ni(110)-O surface and the agreement with various proposed surface structures is discussed.