A two-dimensional molecular template structure of 1,3,5-benzenetricarboxylic acid (trimesic acid, TMA) was formed on a highly oriented pyrolytic graphite surface (HOPG) by self-assembly at the liquid-solid interface. Scanning tunneling microscopy (STM) investigations show high-resolution images of the porous structure on the surface. After the host structure was created, coronene molecules were inserted as guest molecules into the pores. STM results indicate that some of the guest molecules rotate inside their molecular bearing. Further investigations show that single coronene molecules can be directly kicked out of their pores by means of STM.
Details of the design, fabrication, ground and flight calibration of the High Energy Transmission Grating, HETG, on the Chandra X-ray Observatory are presented after five years of flight experience. Specifics include the theory of phased transmission gratings as applied to the HETG, the Rowland design of the spectrometer, details of the grating fabrication techniques, and the results of ground testing and calibration of the HETG. For nearly six years the HETG has operated essentially as designed, although it has presented some subtle flight calibration effects.
This scanning tunneling microscopy (STM) study uses a supramolecular two-dimensional architecture of
trimesic acid molecules adsorbed on a graphite substrate as a host for the incorporation of C60 as a molecular
guest. By choosing a proper solvent, it was possible to verify that self-assembly of the host−guest structure
can be accomplished at the liquid solid interface. Because of the ideal steric match with the molecular bearing
of the host structure, C60 buckminster fullerenes are feasible guests. It was possible to coadsorb C60 within
cavities of the open TMA structure from the liquid phase, and lateral manipulation of the molecular guest by
the STM tip was demonstrated at room temperature. Because of the increased tip−sample interaction as a
result of lower tunneling resistance, a transfer of a C60 molecule from one cavity of the host structure to an
adjacent one was achieved.
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