Near-field scanning optical microscopy of zinc-porphyrin crystals

Using a near-field scanning optical microscope (NSOM), crystals of zinc-por phyrin network materials are characterized with respect to morphology and f luorescence. Needle-shaped crystals are observed. While the topography is f lat, the fluorescence intensity profile in the width direction is approxima tely triangular. A numerical calculation shows that differences between the topographic and optical images cannot be due to an artifact. In some needl e-shaped crystals, the fluorescence emission is strongly peaked at one or b oth ends, possibly indicating a polar crystal structure. (C) 2000 Elsevier Science B.V, All rights reserved.