Adsorption of Nickel on Molybdenum in the Field Emission Microscope

An investigation of the adsorption of nickel on molybdenum is compared with theoretical considerations of adsorption phenomena. Nickel was found to adsorb coherently on molybdenum, preferentially on the (111) planes of the substrate. For coverages of about ⅕ of a monolayer, the following activation energies were determined: $$\begin{array}{c}{Q}_d\text{=(2.10±0.05)\hspace{0.17em}}\mathrm{ev}\mathrm{\hspace{0.17em}(}\mathrm{desorption})\\ Q_m\text{=(1.31±0.08)\hspace{0.17em}}\mathrm{ev}\mathrm{\hspace{0.17em}(}\mathrm{surface\; migration}\hspace{0.17em}\frac{1}{4}\hspace{0.17em}\mathrm{completed})\\ Q_m\text{=(1.42±0.05)\hspace{0.17em}}\mathrm{ev}\mathrm{\hspace{0.17em}(}\mathrm{surface\; migration}\hspace{0.17em}\frac{1}{2}\hspace{0.17em}\mathrm{completed})\\ Q_m\text{=(1.48±0.06)\hspace{0.17em}}\mathrm{ev}\mathrm{\hspace{0.17em}(}\mathrm{surface\; migration}\hspace{0.17em}\frac{3}{4}\hspace{0.17em}\mathrm{completed}\mathrm{).}\end{array}$$ The desorption energy did not vary with degree of completion. Heavy adsorbed layers of nickel were investigated. The equilibrium position of heavy layers was found to be field dependent.