| In this dissertation, I describe the design, construction, calibration and the applications of an ultra high vacuum, low temperature scanning tunneling microscope (UHVLTSTM).;The UHVLTSTM is designed with both ultra high vacuum and low temperature capabilities. This is the first scanning tunneling microscope that can operate at low temperature and in ultra high vacuum. It has a unique capability for optical access. It is constructed in a UHV chamber equipped with a load-lock chamber and other surface preparation and analysis tools, such as thermal evaporation, thermal annealing, ion-beam bombardment, Auger, and LEED. We have used this scanning tunneling microscope to study various sample systems. The two major systems are high T;On high T;The quasi one-dimensional organic conductor studied in this dissertation work is single crystal TTF-TCNQ. Topographic images show the one-dimensional features of this material in great detail, which are consistent with other experiments. The low temperature images clearly display the double-period commensurate charge density wave, which we believe is due to the known Peirls phase transformation of this material. Support for this hypothesis is the observation of an energy gap of about 100 meV at low temperature. |
