Scanning-tunneling and atomic-force microscopy


  • Anonymous


(STM and AFM) are allowing for in situ (in air and under water) imaging of mineral surfaces at previously unattainable nanometer to atomic scales. The four images, which represent a range of STM/AFM applications, were all taken on [001] surfaces of hematite. Counterclockwise from bottom left, these micrographs are described as follows: (1) An STM image of oxygen sites on terraces separated by steps—imaged under oil at -300-mV sample bias. The difference in tunneling current between terrace (blue) and step-edge (pink) sites can be related to differences in local electronic structure that may affect the reactivity of the different sites Terraces step downward toward the lower left. A kink site is apparent along one step. (2) An AFM image in air showing the molecular-scale structure of the hematite surface.