Experimental Persistence Probability for Fluctuating Steps
  The persistence behavior for fluctuating steps on the $Si(111)$ $(\sqrt3 \times \sqrt3)R30^{0} - Al$ surface was determined by analyzing time-dependent STM images for temperatures between 770 and 970K. The measured persistence probability follows a power law decay with an exponent of $\theta=0.77 \pm 0.03$. This is consistent with the value of $\theta= 3/4$ predicted for attachment/detachment limited step kinetics. If the persistence analysis is carried out in terms of return to a fixed reference position, the measured persistence probability decays exponentially. Numerical studies of the Langevin equation used to model step motion corroborate the experimental observations. 
D.B. Dougherty, I. Lyubinetsky, E.D. Williams, M. Constantin, C.   Dasgupta and S. Das Sarma