Dresden 2011 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 8: Poster: Organic Semiconductors
CPP 8.50: Poster
Montag, 14. März 2011, 17:30–19:30, P2
Soft x-ray linear dichroism to explore molecular orientation in STXM — •Stephan Wenzel1, Andreas Späth1, Benjamin Watts2, and Rainer H. Fink1 — 1ICMM, Dept. Chemie & Pharmazie, Univ. Erlangen, Egerlandstraße 3, D-91058 Erlangen, Germany — 2Paul Scherrer Institut, Swiss Light Source, CH-5232 Villigen, Switzerland
Soft x-ray near-edge x-ray absorption fine structure (NEXAFS) is an ideal fingerprint tool for the study of organic substances. This also serves as an excellent contrast mechanism for scanning transmission x-ray microscopy (STXM). Linear dichroism which originates from the anisotropy of NEXAFS resonances further serves as a tool for the study of molecular orientation. We present some microspectroscopic studies of TCNQ and F4-TCNQ, which are commonly used in organic electronic devices. Single crystals were prepared from saturated solutions on commercial ultrathin Si3N4 membranes and imaged in the PolLux STXM at the Swiss Light Source (SLS). We discuss analytical routines to derive the molecular crystal packing in individual nano- and microcrystals from hyperspectral images, e.g., from a series of images recorded at various photon energies (corresponding to a measurement of the NEXAFS spectrum in each pixel of the image series). Such studies can be extended to more complex materials like e.g. oriented polymers in organic solar cells, where the combination of structural and chemical analysis is inevitable. The PolLux STXM is supported by the BMBF (contract 05 KS7WE1).