Dresden 2014 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 5: Focus Session: Feedback Control of Nonlinear Soft and Hard Matter Systems (joint session DY/CPP)
DY 5.2: Invited Talk
Monday, March 31, 2014, 15:30–16:00, HÜL 186
Thermophoretic trapping and steering of single nano-objects with plasmonic nanostructures — •Frank Cichos1, Andreas Bregulla1, Marco Braun1, and Haw Yang2 — 1Molecular Nanophotonics Group, Institute of Experimental Physics I, University Leipzig, 04103 Leipzig, GERMANY — 2Department of Chemistry, Princeton University, Princeton, NJ 08544-2020, USA
The manipulation of single micro- and nano-particles or even single molecules in solution requires to beat Brownian motion with a mechanism that drives objects into a well defined direction. Such a mechanism is provided by the thermophoretic drift of nano-objects in a temperature gradient as generated by optically heated plasmonic nano-structures. Since these tiny heat sources can be switched optically at high frequencies, they provide new means of feedback controlled optical manipulations. Here we report on two experiments controlling individual particles in solution by such a feedback mechanism. The first experiment employs a self-propelled thermophoretic swimmer that is steered in solution by a real-time feedback of the swimmer orientation and position. This type of feedback controlled actuation predicts an increased positional control with decreasing particle size. The second experiment involves the trapping of single colloids and molecules in feedback controlled dynamic temperature fields. While the actual thermophoretic drift is repelling the object from the heat source, the dynamic switching provides and effective potential well, which can be shaped by the feedback details. Both experiments provide huge perspectives for study of interactions in well defined clusters of nano-objects.