Dresden 2011 – scientific programme

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MO: Fachverband Molekülphysik

MO 10: Cluster

MO 10.2: Talk

Tuesday, March 15, 2011, 10:45–11:00, MER 02

Matrix isolation of PTCDA molecules in rare gas samples: clusters vs. bulk matrices — •Matthieu Dvorak¹, Markus Müller¹, Alexandre Rydlo², Stefan Minniberger², Wolfgang Harbich², and Frank Stienkemeier¹ — ¹Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg im Breisgau — ²Institut de Physique des Nanostructures, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne

Matrix isolation spectroscopy of chromophores in rare gas matrices is a convenient way to unravel properties of the host media. The chromophore used in the present case is the PTCDA molecule (C₂₄H₈O₆), a perylene derivative, the fluorescence properties of which are well characterized. The influence of large argon and neon clusters or matrices on the emission and absorption spectra of PTCDA molecules have been studied. Attaching PTCDA molecules to large neon and argon clusters results in an increase of the spectral resolution of more than one order of magnitude when compared to PTCDA probed at thin films or in organic solvents at room temperature. In cryogenic rare gas matrices, site-specific isomers are observed, resulting in a broadening of the absorption spectrum and a splitting of the lines in the fluorescence spectrum. From the comparison between cluster and cryogenic matrix measurements, it can also be concluded that neon and argon clusters are solid and the studied molecules reside on the cluster surface. The quasi absence of PTCDA dimer formation implies a lack of mobility which can be interpreted as the surface being solid.