Surface mass diffusion over an extended temperature range on Pt(111)

Surface mass diffusion is investigated on Pt(111) at temperatures in the range 710–1220 K. This greatly extends the range over which diffusion is known from step fluctuation spectroscopy (SFS). In the present research, a beam of Pt− self-ions is employed to create a suitable structure on step edges. The surface mass diffusion coefficients then follow from the decay of Fourier components observed by low-energy electron microscopy (LEEM) at selected annealing temperatures. The results agree with SFS values where they overlap, and continue smoothly to low temperature. This makes it unlikely that diffusion along step edges plays a major role in step edge relaxation through the temperature range studied. The surface mass diffusion coefficient for the range 710–1520 K deduced from the present work, together with previous SFS data, is Ds = 4 × 10−3 exp(−1.47 eV/kBT) cm2 s−1.