Hamburg 2001 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

SYOF: Organische Festkörper

SYOF 5: Poster Session

SYOF 5.34: Poster

Dienstag, 27. März 2001, 17:00–19:00, Aula S3

Infrared spectroscopic study of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) films grown on H-passivated Si(111) — •Georgeta Salvan, Reinhard Scholz, Marion Friedrich, Thorsten U. Kampen, and Dietrich R. T. Zahn — Institut für Physik, Technische Universität, D-09107 Chemnitz, Germany

Infrared spectroscopy is applied for the characterisation of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) films grown with organic molecular beam deposition (OMBD) on hydrogen-passivated Si(111). Comparing these OMBD grown films with powder spectra, the films show a preferential orientation of the PTCDA molecules close to coplanar with the substrate surface. For deposition of PTCDA films using laser ablation at 1064 nm, the average orientation of the molecules is more random than in the OMBD grown films, but we still find a lower degree of preferential order of the molecules with respect to the substrate surface.

Our experimental findings are analysed in detail with density functional calculations of the infrared active modes of PTCDA, both for a single molecule and for the monoclinic bulk crystal. The calculated Davydov splittings of the most intense IR modes are in good agreement with the experimental observations.