Dresden 2014 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 4: Crystallization, Nucleation and Self Assembly I

CPP 4.8: Talk

Monday, March 31, 2014, 11:30–11:45, ZEU 114

Influencing molecular thin film growth with light — •Linus Pithan¹, Hannes Zschiesche¹, Anton Zykov¹, Christopher Weber¹, Sebastian Bommel², and Stefan Kowarik¹ — ¹Humboldt Universität, Fachbereich Physik, Berlin — ²DESY, Hamburg

The possibilities to control the orientation and structure of molecular thin films during growth are limited to very few degrees of freedom e.g. the substrate temperature and molecular deposition rate. Here we show that light can influence the molecular growth.

Vacuum deposited α-sexithiophene (α−6T) films (OMBE) tend to grow in different crystal structures. Most prominent are the low temperature (LT) and high temperature (HT) polymorphous. Both structures are found to coexist when KCl is used as substrate material, as observed by real-time x-ray diffraction studies. Using light illumination during growth we show that the coexistence can be controlled and the phase purity can be increased by eliminating the HT phase. This demonstrates the possibility to use laser illumination as new control parameter to influence organic molecular beam deposition.