%A Petro Maksymovych
%T NOVEL SURFACE CHEMISTRY OF SINGLE MOLECULES AND SELF-ASSEMBLEDSTRUCTURES BY SCANNING TUNNELING MICROSCOPY
%X This thesis demonstrates the richness of Scanning Tunneling Microscopy (STM) as amethod to understand surface chemistry and physics and to explore the new frontiers in singlemoleculesurface reactions and molecular self-assembly. Organosulfur molecules on the Au(111)surface were studied to address unresolved and controversial issues about self-assembledmonolayers of alkanethiol molecules on gold surfaces. The key new finding is that the thermalsurface chemistry of alkanethiol molecules occurs in a dynamic chemical environment thatinvolves reactive gold adatoms to which the alkanethiol molecules chemically bond. Theproblem of alkanethiol self-assembly is thus transformed from the realm of adsorption on asurface toward organometallic surface chemistry, which is anticipated to have broad implicationsfor the field. Molecules containing a disulfide (S-S) bond were also found to be a spectacularmodel system for exploring electron-induced surface chemistry. In particular, the atomicallylocalizedinjection of electrons from the metal tip of the tunneling microscope is capable ofproducing highly delocalized chemical reactions by means of surface current of hot-electrons.Chemical reactions can therefore be a unique approach to the measurement of the local transportof hot-electrons on metal surfaces. Finally the concepts of self-assembly and electron-inducedchemistry are combined through an observation of an unusual process that flips the chirality ofmolecules self-assembled on the surface by a radical-like chain reaction. This experimentdemonstrates how self-assembly enables a new reaction coordinate by optimizing the stericfactor of the chemical reaction.
%D 2007
%K alkanethiol; gold; hot-electron; microscopy; self-assembly; STM; tunneling
%I University of Pittsburgh
%L pittir7771