Scaling transition of the time dependence of step fluctuations on Cu(111)

We have studied the time dependence of equilibrium step fluctuations on Cu( 111) at temperatures between 430 and 510 K for very long time intervals. We find a crossover of the time exponent of the step correlation function in time: for short times, the exponent is alpha=1/4. For long times, a transit ion to an exponent alpha=1/2 is observed. This crossover in time is analogo us to a crossover of the exponent observed previously as a function of temp erature. The temperature dependence of the fluctuations in the long-time li mit is consistent with an underlying transport mechanism via detachment/att achment of atoms from kinks onto the terraces. (C) 1999 Elsevier Science B. V. All rights reserved.