3-DIMENSIONAL MONTE-CARLO SIMULATIONS OF ROUGHNESS DEVELOPMENT FROM DIFFERENT MECHANISMS APPLICABLE TO THE DISSOLUTION OF A PURE SOLID

Three-dimensional (3D) Monte Carlo simulations based upon different mo dels for the dissolution of a pure solid under a surface reaction cont rol are presented. The analysis of the x-y and y-z profiles resulting from Monte Carlo snapshots using the dynamic scaling theory shows that when stochastic noise and lateral advance of the reacting interface a re included in the dissolution processes, the roughness exponents are alpha congruent to 1/3 and beta congruent to 1/4, approaching the appr oximate values predicted by the Kardar, Parisi, and Zhang motion equat ion in 3D. Otherwise, the addition of surface diffusion relaxation to the model results in alpha congruent to 1.0 and beta congruent to 0.25 , for the early stages of the process, and in an unstable surface with alpha congruent to 1.0 and beta > 0.5 for the advanced ones. The prog ressive hindrance of the interlayer mass transport results in a value of beta which increases from 0.25 to 0.45, whereas the value of alpha remains unchanged. Nonlocal effects stabilizing cavities also result i n an unstable surface with beta > 1. Results from these models are com pared to those obtained from real time STM imaging data on silver and copper electrodissolution in aqueous perchloric acid solution at 298 K .