Studies on Stereoselectivities on a Clay Surface by STM Method

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This project intended to apply the scanning tunneling microscopy (STM) for the observation of a clay surface. We recently discovered that a certain kind of metal complex forms a stereoregular adsorbate layer on a surface of a clay mineral. For this propose, a new instrument of STM has been constructed and its function has been established. Our STM instrument enables us to observe a surface of graphite (HOPG) reproducibly with the resolution of 0.1-0.2 A in the x, y and z directions. The scan time for 100 A length is less than 10 seconds. Accordingly the surface that is unstable with time can be observed with this instrument. With this instrument, a graphite surface modified with a thin film of a clay is observed. As a result, it is confirmed that the image due to the substrate (graphite) surface is observed when a clay film is thin enough. The results imply that a tunneling electron penetrates through a clay film to reach a platinum tip. Thus it is expected that a molecule adsorbed on a clay film might give its own image with the present method. It is now in progress to confirm this possibility.