Determination of Step Free Energies from Island Shape Fluctuations on Metal Surfaces

Abstract
The absolute measurement of free energies associated with crystal steps on a metal surface has been a long-standing problem. We report a reliable estimate of the step free energy on a Cu(111) crystal surface, based on an analysis of island shape fluctuations directly imaged by scanning tunneling microscopy. The result of 0.22 eV per atomic distance for steps running into close-packed directions is in good agreement with theoretical predictions.