Core hole-electron correlation in coherently coupled molecules.
We study the core hole-electron correlation in coherently coupled molecules by energy dispersive near edge x-ray absorption fine-structure spectroscopy. In a transient phase, which exists during the transition between two bulk arrangements, 1,4,5,8-naphthalene-tetracarboxylicacid-dianhydride multilayer films exhibit peculiar changes of the line shape and energy position of the x-ray absorption signal at the C K-edge 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. By applying this model we can furthermore quantify the coherence length of the delocalized core exciton.
Experimentelle Physik VII and Röntgen Research Center for Complex Material Systems RCCM, Universität Würzburg, 97074 Würzburg, Germany. achim.schoell@physik.uni-wuerzburg.de
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Scholz
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Holch
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Sauer
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Wiessner
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Schöll
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