Friday, July 13, 2007, 9:30 am — Bldg 555, Room 300
Since the invention of the scanning tunneling microscope (STM), it has become one of the most important tools for surface science. The operation of the STM is not only limited to imaging single atom/molecules in real space but also exploring the capabilities to resolve energy states of a surface at a fixed position.
I will begin my talk by discussing the design and construction of a low temperature STM for atom/molecule manipulation. I will present an atom-by-atom extraction process from a native silver cluster using the tip-cluster interaction. The manipulation signal, combined with total energy calculations and molecular dynamics simulations, shows lowering of the atom-extraction barrier upon approaching the tip to the cluster.
I will present recent results for a nitrogen polar, gallium rich GaN(0001) surface, investigated at 5K using LT-STM and scanning tunneling spectroscopy (STS). We observe four novel, low temperature surface reconstructions which are different from the room temperature surface reconstructions. By means of STS measurements and voltage dependent imaging, novel features of the voltage-dependent surfaces structure are associated with two of the intrinsic surface states of GaN(0001).
Finally, I will present some results on DNA/CNT hybrid
system using STS/STM at low temperature.
Hosted by: Peter Sutter
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