Surface microscopy of porous materials

Atomic force microscopy (AFM) and high-resolution electron microscopy (HREM) are shown to be powerful tools for the investigation of crystal growth processes in microporous materials. Observations at atomic resolution of zeolite surfaces in the absence and presence of adsorbates reveals both surface structure and the mode of interaction of potential templates for crystallisation. A layer-by-layer growth mechanism is observed for many open-framework materials with organic templates acting by keying into exposed surfaces followed by clathration during growth of the subsequent layer. The role of defects in modifying growth processes can be discerned and predictions made for altering conditions of growth to control the defect type and density. Simulation of AFM micrographs permits the relative rates of fundamental growth processes to be ascertained. (C) 2001 Elsevier Science Ltd. All rights reserved.