AVS 47th International Symposium
    Surface Science Tuesday Sessions
       Session SS2-TuA

Paper SS2-TuA7
Theory of Single Molecule Vibrational Spectroscopy and Microscopy

Tuesday, October 3, 2000, 4:00 pm, Room 209

Session: Stimulated Processes and Excitations
Presenter: N. Lorente, Chalmers/Gothenburg University, Sweden
Authors: N. Lorente, Chalmers/Gothenburg University, Sweden
M. Persson, Chalmers/Gothenburg University, Sweden
Correspondent: Click to Email
A recent breakthrough in Surface Science has been the experiments demonstrating vibrational spectroscopy and microscopy of single molecules by inelastic electron tunneling using a scanning tunneling microscope.@footnote 1@ Based on density functional theory and a many-body generalization of Tersoff-Hamann theory, we have developed a theory and calculational method for this new spectroscopy.@footnote 2@ We apply our theory to acetylene on copper and explain why only the carbon-hydrogen stretch modes are observed in terms of elastic and inelastic contributions to the tunneling conductance. The calculated values for the changes in tunneling conductance induced by these stretch modes and their spatial images are in good agreement with experiments. We find that the symmetry of the adsorbate-induced states makes the inelastic signal for the anti-symmetric stretch mode to dominate over the signal for the symmetric one. This result is in agreement with experiment and shows that the symmetries of the lowest unoccupied molecular states has an important influence on the spatial dependence of the vibrationally inelastic tunneling.@footnote 3@ @FootnoteText@ @footnote 1@ B. C. Stipe, M.A. Rezaei, and W. Ho, Science 280, 1732 (1998). @footnote 2@ N. Lorente and M. Persson, (submitted to Phys. Rev. Lett.). @footnote 3@ N. Lorente, M.Persson, L.J. Lauhon, and W. Ho, (to be submitted).