Berlin 2012 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 10: Interfaces and Thin Films II

CPP 10.5: Talk

Tuesday, March 27, 2012, 10:45–11:00, C 130

Diffusion study in thin free-standing liquid crystal films — •Benjamin Schulz and Christian Bahr — MPI für Dynamik und Selbstorganisation, 37077 Göttingen

Free-standing liquid crystal films are liquid films that are spanned over a supporting frame and stable without an underlying substrate. Hence it becomes possible to study the pure material properties in thin films as no surface interaction comes into play. However, not much is known about the changes in diffusion in such films as compared to bulk properties.

We study the translational molecular dynamics in free-standing films using single molecule tracking. For this we dissolve a small amount of dye molecules to then image their diffusive behaviour. This allows us to directly study the dynamics in the film on molecular level. We focus on the diffusion in films at the transition to complete 2-dimensional systems with a thickness of only a few layers, which leads to a strong increase in diffusion for some materials. Also we look into the diffusion properties in proximity to phase transitions as for some materials it is known that they show layer-by-layer phase transitions in the layers directly at the free surface [1].

[1] Jin et. al., Phys. Rev. E. 49 (1994), R4791-R4794