Surface islands nucleated by a beam of energetic self-ions on Pt(111): A low-energy electron microscopy study*

Using low energy electron microscopy (LEEM), we observe the adatom and advacancy islands nucleate and evolve when clean Pt(111), in the temperature range 750-1300K, is bombarded by a beam of Pt$^{-}$ ions of various energies. The source of negative ion beam is incident on the sample at normal incidence with impact energies selectable in the range of 0 to 5 keV, and with current densities up to 40 $\mu $A/cm$^{2}$. We describe briefly initial experiments done with LEEM-Ion accelerator tandem namely the investigations of relaxing steps extending the range over which surface mass diffusion coefficient D$_{s}$ is known on Pt(111) and observed neutral energy of 245 eV, at which sputtering balances the self-ion input. The results reveal a previously unobserved symmetry between the chemical potentials $\mu $* required to nucleate the adatom and advacancy islands. Linear response theory is employed to relate $\mu $* to ion beam flux; the observations confirm that its use is valid above 1000K.