Dresden 2014 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 24: Crystallography in Materials Science (Joint Session with KR)

DF 24.8: Talk

Thursday, April 3, 2014, 17:15–17:30, CHE 184

Selective preparation of single-crystalline alpha- & beta-phase perylene platelets — •André Pick and Gregor Witte — Molekulare Festkörperphysik, Philipps-Universität Marburg, 35032 Marburg

Though polarization resolved optical absorption spectroscopy in transmission geometry is a simple method to characterize optoelectronic properties of pi-conjugated molecular crystals their large absorption requires rather thin crystals. Moreover such studies are complicated by the presence of polymorphism and structural defects like twinning. For the case of the polycyclic aromatic hydrocarbon perylene two crystalline phases (alpha and beta) are known which comprise different molecules per unit cell. Both crystalline phases exhibit also characteristic differences in the habitus of single crystals which allows their differentiation. Here, we present a method to selectively prepare thin platelets of both polymorphisms, which are suitable for optical studies of single crystals. In order to get full morphological information, the crystallites were characterized by means of optical microscopy, X-ray diffraction and atomic force microscopy.