Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 77: Focussed Session: Towards a Quantitative Understanding of Complex Adsorption Structures: Surface Science goes Organic III

O 77.1: Topical Talk

Donnerstag, 3. April 2014, 16:00–16:30, TRE Phy

Infrared-Spectroscopy applied to ultrathin organic films. — •Peter Jakob — Physics Department, Philipps-University Marburg, 35032 Marburg, Germany

IR-spectroscopy is commonly referred to as a fingerprint technique to identify molecular species. However, this method can do better! The high spectral resolution and polarization dependence of vibrational modes allows to distinguish between different local environments (→ lateral interactions), bonding configurations (→ adsorption site and orientation), and phases (monolayer, bilayer, bulk) of large organic molecules with high selectivity. Thereby IR spectroscopy is non-invasive/destructive, obeys strict selection rules, and provides adequate sensitivity to detect even slight differential changes within grown films. Selected examples of various effects and curiosities associated with ultra-thin molecular layers will be presented, demonstrating the excellent quality and potential of infrared spectroscopy in studying such systems. Notably, for molecular species exhibiting a partially filled (former) LUMO, IR spectra are influenced by interfacial dynamical charge transfer (IDCT) between molecule and metal substrate /1/. By means of line-shape analysis of the associated Fano-like absorption profiles the electron dynamics (electron transfer time) between contact primer layer and metal substrate can be estimated.

/1/ F.S. Tautz, Progress in Surface Science 82 (2007) 479-520.