Stephen Thurgate

In this work, the problems of what happens to the image potential as a charge approaches a metal surface and of how oxygen is chemisorbed onto clean metal surfaces are investigated by the techniques of low energy electron diffraction. Auger electron spectroscopy and contact potential difference measurement. Both Copper and Nickel low index planes are investigated. LEED intensity curves are analysed using a previously developed model of the surface barrier. From these analyses, conclusions are drawn as to the location and shape of the surface barrier on the clean surfaces and the effect on the barrier of exposure to oxygen. The chemisorption of oxygen on Cu(001), Cu(110), Cu(lll) and Ni(001) is monitored by the above techniques and the results compared with those appearing in the literature. The various ordered overlayers appearing on Cu(001), Cu(110) and Ni(001) are examined. The kinetics of their formation are investigated by AES and CPD measurements. These are contrasted with the kinetics governing the formation of the disordered overlayers on Cu(lll). The empirical relationship between surface smoothness and the relative height of the fine structure features and Bragg features in the LEED is investigated. It is established that a smooth surface produces relatively intense fine structure features. This relationship is used to test various proposed models of overlayer structures. This test appears to rule out several models proposed for overlayers on Cu(001), Ni(001) and Cu(110).