Passler, Mark A.

Low Energy Electron Diffraction is used to determine the different structures formed by the CO adsorption on the Ni(110) surface at two coverages. At full coverage the superlattice is Ni(110)-(2 x 1)2CO. For this superlattice, the CO molecules adsorb at the short bridge sites with a 20 degrees common tilt in the +-[001] directions. The Ni-C and the C-O bond lengths are 1.85 A and 1.15 A, respectively. In the Ni(110)-c(2 x 4)3CO superlattice structure, which is formed at an intermediate coverage, the CO molecules adsorb at the top sites with two types of configurations on alternate (110) rows. Half the rows are filled with CO molecules having a 9 degrees zig-zag common tilt in the $\pm$ (001) directions, and half the rows are half filled with untilted CO molecules. The Ni-C and the C-O bond lengths are 1.67 A and 1.15 A, respectively. The possible role of hydrogen in the formation of the surface structure is discussed.

The purpose of this thesis is to provide a comprehensive overview of an important technique (low energy electron diffraction) used in the study of surface phenomena. Within this context, the LEED studies of NO adsorbed on the Ni(110) surface and of Fe-33%Ni(111) near its Martensitic transition temperature were done to determine their surface structures.

The purpose of this thesis is to provide a comprehensive overview of two important techniques (low energy electron diffraction (LEED) and Auger electron spectroscopy (AES)) used in the study of surface phenomena. Within this context, a LEED study of Fe-33%Ni near its Martensitic transition temperature (155K) was done to determine if there is a surface precursor to the Martensitic transformation. Based on visual comparison of experimental and theoretical I-V curves for two diffracted beams, it has been concluded that at 166K no such precursor is apparent. The taking of LEED data nearer the transition temperature was made impossible by the unexpected transformation of our sample during cooling. Further study with a new sample is planned for the immediate future.