MODIFICATION OF ATOMIC STEPS BY ADSORBATES OBSERVED BY LOW ENERGY ELECTRON MICROSCOPY AND PHOTOEMISSION MICROSCOPY

The influence of adsorbates on the structure of atomic steps on a Mo{110} single crystal surface is studied by Low Energy Electron Microscopy and Photoemission Electron Microscopy. Adsorption and proper annealing of a Cu double-layer produces a large number of atoms at atomic step positions along the Mo[001] direction. The number of kink sites increases by the formation of pits. Atoms at atomic step sites multiply as atomic steps migrate past step pinning centers. Cu adsorbs at the bottom of atomic steps modifying Mo step sites there, whereas molybdenum carbide produced by thermal cracking of CO forms at both the top and bottom of atomic steps, modifying Mo sites at both top and bottom.