AFM images of dissolution and growth on a calcite crystal

We present atomic-force-microscope (AFM) images of aqueous dissolution and growth of monolayers on the cleavage plane of calcite. These processes were observed in real time and in situ. Dissolution in 0.015N NaOH occured primarily by faceting and expansion of pre-existing surface pits and by removal of islands. No new dissolution sites were observed to nucleate during this process. We also observed a simple growth sequence wherein CaCO₃ monolayers were deposited on the calcite surface by uniformly advancing steps. Atomic resolution was readily obtained, even at larger-scale features such as steps and etch pits. This shows the potential of the AFM to study deposition and removal of individual molecules on a crystal surface in solution.