In this thesis, we developed and applied a real-time method, called LITD/LEEM method, to study CO diffusion on the Pt(111) surface. An adsorption study was first carried out with a goal to determine the relationship between the LEEM image intensity and CO coverage on the Pt(111) surface. With the use of the experimental results from HREELS study [85], the relationship between the LEEM intensity and CO coverage was determined....[ Read more ]

In this thesis, we developed and applied a real-time method, called LITD/LEEM method, to study CO diffusion on the Pt(111) surface. An adsorption study was first carried out with a goal to determine the relationship between the LEEM image intensity and CO coverage on the Pt(111) surface. With the use of the experimental results from HREELS study [85], the relationship between the LEEM intensity and CO coverage was determined.

In the diffusion experiment, a non-equilibrium concentration profile was created by laser-induced thermal desorption (LITD) on the Pt(111) surface on which a uniform layer with a prescribed CO coverage was initially adsorbed. The whole profile evolution process was then observed by LEEM. To determine the diffusion coefficient, a diffusion model was used to predict the temporal evolution of the experimental concentration profile. By assuming spatial- and coverage- dependent diffusivity D(r,θ), which is attributed to laser-induced damages created upon the substrate surface by LITD, the modeled concentration profiles fitted well with the experimental results.