Dresden 2003 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 10: Experimente mit Einzelmolekülen

CPP 10.3: Vortrag

Donnerstag, 27. März 2003, 10:30–10:45, ZEU/160

Single molecule dynamics in liquid and polymer films — •Frank Cichos, Arne Schob, Jörg Schuster, and Christian von Borczyskowski — Institut für Physik 122501, TU Chemnitz, 09107 Chemnitz

Single molecule microscopy techniques deliver a tool to study dynamics on a nanoscopic scale with the advantage of resolving distributions of observables rather than mean values. Therefore it is possible to study directly heterogeneity, which is present in many systems. We apply single molecule video microscopy to study the rotational and translational motion of single dye molecules in ulrathin liquid films and thick polymer films close to the glass transition. The experiments in polymer films show a temperature dependent heterogeneous rotational diffusion close to the glass transition. Individual dye molecules obey a continuous change in the rotational diffusion with time. Translational motion is not observed close to the glass transition even though our spatial resolution reaches 40 nm. The first detectable translational diffusion is observed about 70 degree above the glass transition with diffusion constants of 10¹¹ cm²/s. The translational diffusion is homogeneous in nature. A film thickness dependence of the diffusion is discussed and compared to the translational diffusion in ultrathin liquid films which is found to be heterogeneous.