Dresden 2003 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

O: Oberflächenphysik

O 13: Hauptvortrag Lorente

O 13.1: Hauptvortrag

Dienstag, 25. März 2003, 09:30–10:15, HSZ/02

Mode excitation and reaction pathways induced by the scanning tunneling microscope — •Nicolas Lorente — Lab. Collisions Agrégats et Réactivité, UMR 5589, Unviersité Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex, France

The scanning tunneling microscope (STM) can induce molecular vibrations. This is detected by changes in the tunneling conductance as the bias voltage matches a vibrational excitation threshold. Vibrational spectroscopy is available for a unique molecule. Nevertheless, the experimental results present several challenges: few modes are detected, certain symmetries are dominant, and site and conformation properties affect the detection. Despite these difficulties, this technique is proving to be of uttermost importance in the analysis of molecular adsorbates and in their manipulation.

We will present a general theory that can predict the outcome of STM induced vibrational spectroscopy. We will analyze the above challenges and show quantitative results.

The excitation of localized vibrations can be the precursor of reaction pathways. We will present the first results of mode selected chemistry by tunneling electrons. These results can be understood with the above theoretical treatment enlargened to include vibrational damping and intermode coupling. We will show that intermode coupling is very efficient on metallic surfaces.