Single molecules reorientation reveals the dynamics of polymer glasses surface.

The polymer glass surface can be many orders of magnitude more mobile than the interior. We probe dynamics with reorientation of single dye molecules spin-coated onto polymer films. Rotation jumps in transition dipole orientation are observed for approximately 30% of all single molecules. It is found for the first time that there are mainly three typical jumping patterns of orientation: dithering jump, alternate jump and stepping jump patterns. The distribution of rotational correlation time are used to characterize the dynamics of polymer glass surfaces.