Capillary waves and thermodynamics of multisteps on Pt(1 1 1)

We describe observations of multisteps, up to n=5 steps high, that form on Pt(1 1 1) at temperatures above 1400 K. Using step fluctuation spectroscopy, we determine the multistep stiffnesses, β̃n, and so estimate their line free energies, assumed isotropic. Measurements of mode relaxation times τnq, for modes of wavevector q, reveal that β̃nτnq/n2 depends only weakly on step height, n, in agreement with capillary theory. From the measured energies, we infer that multisteps have large free energies of internal motion, such that the net thermal free energy, including capillary modes, undergoes only small changes when steps merge.