Regensburg 2010 – scientific programme
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O: Fachverband Oberflächenphysik
O 25: Metal substrates: Adsorption of organic / bio molecules III
O 25.5: Talk
Tuesday, March 23, 2010, 11:30–11:45, H36
Vibrational spectroscopy of 4-mercaptopyridine on Au(111): A comparison of scanning tunneling spectroscopy and calculations — •Norbert Maurer1, Anna Tschetschetkin1, Berndt Koslowski1, Paul Ziemann1, Inga Respondek2, and David M. Benoit2 — 1Institut für Festkörperphysik — 2Nachwuchsgruppe Theorie SFB 569, Universität Ulm, Albert-Einstein-Allee 11, D-89081 Ulm
Notion of the adsorption structure and vibrational properties is essential to understand electronic transport across molecules and, therefore, is an essential issue in the field of molecular electronics. Scanning tunnelling microscopy (STM), scanning tunnelling spectroscopy (STS), and especially inelastic electron tunnelling spectroscopy (IETS) is ideal to investigate these properties on a single-molecular basis. We employ these techniques to reveal the properties of 4-mercaptopyridine (4MPy) on Au(111) and compare those to, e.g., DFT calculations. We put emphasis on IETS where we find about 20 excitations in the energy range 0-200 meV. Results are compared to calculations based on the vibrational self-consistent field method [1] and earlier experimental results [2,3]. We conclude that 4MPy adsorbs at elbow sites, in the fcc region, and at step edges preferentially in a bridge configuration thereby ruling out a model proposed earlier which suggests that adsorption of a single 4MPy is accompanied by a Au ad-atom.
[1] I. Respondek and D.M. Benoit, J. Chem. Phys 131, 054109 (2009). [2] Yu, et al., Nano Lett. 8 (7), 1923 (2008). [3] Zhang, et al., J. Raman. Spec. 38, 1106 (2007).