@PhdThesis{dbt_mods_00032962,
  author = 	{Meierott, Stefan},
  title = 	{Spectroscopic line shapes of electronic and vibrational excitations of single-atom and single-molecule junctions},
  year = 	{2017},
  month = 	{Sep},
  day = 	{15},
  address = 	{Ilmenau},
  keywords = 	{Experimentalphysik; Rastertunnelmikroskopie; Kondo-Effekt},
  abstract = 	{The Kondo effect and inelastic electron tunneling are important physical effects that give rise to Fano-like line shapes in the current-voltage characteristics through single adatoms and admolecules. In this work an ultra-high vacuum low-temperature scanning tunneling microscope is optimized to make these features accessible in scanning tunneling spectroscopy.  Following this, experiments are conducted. First, the single-Co Kondo effect on Au(110) is examined. The amplitude of the peak-like Abrikosov-Suhl resonance is found anisotropically distributed across obliquely adsorbed adatoms. The anisotropic evolution is traced to the varying tip-substrate distance across the adatom. Additionally, fitting of peaked Fano line-shapes is discussed. Characteristic properties of the Fano asymmetry parameter are extracted from experimental evidence and from simulations. An improved parameterization is suggested in order to reduce the parameter space for nonlinear optimization. An angular representation of the asymmetry parameter gives rise to the estimation of uncertainties using linear error propagation. Second, inelastic tunneling spectroscopy at C60 molecules adsorbed to Pb surfaces is reported. By deliberately functionalizing the tunneling tip with single C60 molecules the electronic structure is tuned. Coincidently, vibrational line shapes are affected. The varying electronic structure at different adsorption sites on the Pb(111) surface affects vibrational line shapes likewise. Thus, a clear-cut correlation between vibrational line shapes and the electronic structure is derived. These findings represent an experimental proof to theoretical predictions about the contribution of resonant processes in inelastic tunneling spectroscopy. Further, electronic transport through C60 on Pb(111) is examined for varying tip-molecule distance. The signature of the lowest unoccupied molecular orbital is found to shift towards the Fermi energy with decreasing tip-molecule distance. Vibrational line shapes are governed by the relative molecule position inside the junction, rather than the varying electronic structure. These observations stress the importance of the junction symmetry in inelastic electron tunneling.},
  url = 	{https://www.db-thueringen.de/receive/dbt_mods_00032962},
  url = 	{http://uri.gbv.de/document/gvk:ppn:897798279},
  file = 	{:https://www.db-thueringen.de/servlets/MCRFileNodeServlet/dbt_derivate_00039120/ilm1-2017000365.pdf:PDF},
  language = 	{en}
}