Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 14: Organic/bio Molecules on Metal Surfaces II
O 14.11: Vortrag
Montag, 31. März 2014, 18:30–18:45, TRE Phy
Structural phase dynamics and intermolecular coupling studied by energy-dispersive NEXAFS — •Markus Scholz1,2,3, Christoph Sauer1,2, Michael Wiessner1,2, Than-Nam Nguyen1,2, Achim Schöll1,2, and Friedrich Reinert1,2 — 1Universität Würzburg, Experimentelle Physik VII, Am Hubland, D-97074 Würzburg — 2Karlsruher Institut für Technologie (KIT), Gemeinschaftslabor für Nanoanalytik, D-76021 Karlsruhe — 3Present address: Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, D-22761 Hamburg
We study the formation of a 3D geometric structure in molecular films, which emerges from an initially amorphous layer by the means of energy-dispersive near edge x-ray absorption fine-structure spectroscopy. This novel technique allows NEXAFS experiments with full spectroscopic information on the time scale of seconds. On the example of NTCDA multilayer films, we identify several sub-processes involved in the structure formation and quantify thermodynamic parameters [1]. In a particular transient phase, which exists only for several minutes during the structure formation, we observe peculiar changes of the line shape and energy position of the C K-NEXAFS signal with respect to the bulk and gas phase spectra. By a comparison to a theoretical model based on a coupling of transition dipoles, which is established for optical absorption, we demonstrate that the observed spectroscopic differences can be explained by an intermolecular delocalized core hole-electron pair [2]. [1] M. Scholz et al, New J. Phys. 15, 083052 (2013). [2] M. Scholz et al, Phys. Rev. Lett. 111, 048102 (2013).