Interplay between step velocity and morphology during the dissolution of CaCO3 surface

The interplay between the velocity and morphology of steps during the dissolution of the-cleaved CaCO3(<10(1)over bar 4>) surface in aqueous solution has been studied using atomic force microscopy (AFM). The experimental results were analyzed based on the terrace-ledge-kink model. Real-time AFM images show that, in the surface reaction regime, steps not only retreat at constant velocities which depend only on the atomic structure of the step, but also preserve a straight-edge morphology during the course of dissolution. The straight step morphology suggests that the nucleation of kinks is balanced by the annihilation of the kinks at the step during the dissolution. This result, along with the constant step velocity, can be explained in terms of a kink-kink annihilation process. (C) 1996 American Vacuum Society.