| A homemade variable temperature scanning tunneling microscope (STM) was used to fabricate nanostructures on metal surfaces and to probe their electronic, magnetic, and vibrational properties via imaging and local spectroscopy. The main goal of the research presented in this dissertation was to gain insights into the physics and chemistry at the nanoscale for possible future application to molecular electronics and spintronics.; The use of a STM as an atomic-scale reactor and analyzer was demonstrated by building single molecules from the bottom up and characterizing the reactants and products. Individual CO molecules adsorbed on a Ag(110) surface was vertically transferred onto the apex of the STM tip and subsequently placed down on top of the Fe and Cu adatoms to form single Fe and Cu carbonyls. Inelastic electron tunneling spectroscopy with the STM (STM-IETS) enabled vibrational analyses of the reactants and products as well as structural characterization. Spatial mapping of the CO vibrational intensities revealed a marked difference between the bonding geometries of the Fe and Cu carbonyls. Bonding geometries and vibrational properties of various metal carbonyls (CrCO, MnCO, FeCO, PdCO, CuCO, AgCO, and AuCO) on a NiAl(110) surface were compared by STM-IETS.; Electronic states of magnetic atoms (Mn, Fe, and Co) on a NiAl(110) surface were probed by scanning tunneling spectroscopy. Resonance peaks characteristic of each magnetic species were observed in the unoccupied density of states. Comparison of the measured dI/dV spectra with calculations by density functional theory revealed spin splitting in the unoccupied resonance states with s and p characters. Magnitude of the resonance splitting for the adatoms scaled with the calculated values of magnetic moments. Magnetic dimers, trimers, and chains were assembled from individual magnetic atoms. Controlled atom manipulation with the STM enables 'atom-by-atom' construction of nanostructures where neighboring atoms can be systematically substituted with elements of different magnetic properties. The spin-split resonance structures of the fabricated nanostructures exhibited signatures of their internal magnetic coupling. This novel approach probes the evolution of electronic and magnetic properties of nanostructures as functions of size and constituents. |
