45 research outputs found
Experimental Persistence Probability for Fluctuating Steps
The persistence behavior for fluctuating steps on the 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 . This is consistent with the value of 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.Comment: LaTeX, 11 pages, 4 figures, minor changes in References sectio
Survival in equilibrium step fluctuations
We report the results of analytic and numerical investigations of the time
scale of survival or non-zero-crossing probability in equilibrium step
fluctuations described by Langevin equations appropriate for
attachment/detachment and edge-diffusion limited kinetics. An exact relation
between long-time behaviors of the survival probability and the autocorrelation
function is established and numerically verified. is shown to exhibit
simple scaling behavior as a function of system size and sampling time. Our
theoretical results are in agreement with those obtained from an analysis of
experimental dynamical STM data on step fluctuations on Al/Si(111) and Ag(111)
surfaces.Comment: RevTeX, 4 pages, 3 figure
Distinguishing step relaxation mechanisms via pair correlation functions
Theoretical predictions of coupled step motion are tested by direct STM
measurement of the fluctuations of near-neighbor pairs of steps on
Si(111)-root3 x root3 R30 - Al at 970K. The average magnitude of the
pair-correlation function is within one standard deviation of zero, consistent
with uncorrelated near-neighbor step fluctuations. The time dependence of the
pair-correlation function shows no statistically significant agreement with the
predicted t^1/2 growth of pair correlations via rate-limiting atomic diffusion
between adjacent steps. The physical considerations governing uncorrelated step
fluctuations occurring via random attachment/detachment events at the step edge
are discussed.Comment: 17 pages, 4 figure