Ultrahigh vacuum reflection electron microscopy has been applied to single fluctuations caused by step pinning in the strain fields of an edge dislocation emerging at a surface. The effective step edge stiffness was deduced from the relaxation rate of a single perturbation in the shape of steps at high temperatures in the regimes far from thermodynamical equilibrium. The experimental step stiffness evaluated under dynamical conditions of sublimation was compared with theoretical predictions from recently developed theories.

• Received 16 June 1995

DOI:https://doi.org/10.1103/PhysRevLett.76.94