Dresden 2014 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 4: Crystallization, Nucleation and Self Assembly I

CPP 4.3: Vortrag

Montag, 31. März 2014, 10:00–10:15, ZEU 114

Guided assembly of nano-particles exploiting forces induced by 3D confinement — •Stefan Fringes¹, Colin Rawlings¹, Heiko Wolf¹, Urs Duerig¹, Madhavi Krishnan², and Armin Knoll¹ — ¹IBM Research, 8803 Rüschlikon, Switzerland — ²Institute of Physical Chemistry, University of Zurich, 8057 Zurich, Switzerland

It has been shown previously that charged nanoparticles can be stabilized in a static nano-fluidic slit due to the formation of the electric double layer. By shaping the topography of the confining interfaces, a trapping potential is established for the nanoparticle, which overcomes the Brownian motion and traps the nanosized object for several hours [1]. Here we demonstrate a mechanical setup capable of controlling the confining surfaces with sub-nanometer precision. By controlling the slit height, the strength of the trapping potential is directly controlled. The shape of the potential is also defined by the shape of the topography, which is carved out of a thermally decomposable polymer film by 3D thermal Scanning Probe Lithography (tSPL) [2]. The potential landscape is experimentally determined by observation of the particle motion at high frame rates using Interferometric scattering imaging. The undissociated polymer surface has a lower energy barrier for direct contact. We demonstrate that this energy barrier can be overcome at small separations, where the van der Waals force dominates providing stable deposition. In addition, the particles can be transferred to the substrate of choice by thermal decomposition of the polymer film.

[1] Krishnan et al., Nature 467, 692-695, 2010

[2] D. Pires, A.W. Knoll et al., Science 328(5979), 732-735, 2010