Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 25: Brownian Motion and Transport (jointly with DY, CPP)

TT 25.12: Talk

Monday, March 16, 2015, 18:15–18:30, BH-N 243

Calibration free 3D tracking of confined nanoparticles in a tunable nanofluidic slit — •Stefan Fringes, Michael Skaug, Heiko Wolf, Urs T. Dürig, and Armin W. Knoll — IBM Research, 8803 Rüschlikon, Switzerland

We investigate the behavior of nanoparticles in a nanofluidic slit with tunable confinement and spatial and temporal resolution of 10nm and 2ms, respectively. The high speed detection of the particles' X, Y and Z coordinates allows us to obtain the spatiotemporal probability distribution of individual particles and thus to study their confining potential-landscape both in lateral and vertical direction. To obtain the 3D trajectory of a nanometer-sized particle we use interferometric scattering detection (iSCAT). The method exploits the interference between the scattered wave from the particles and the highly reflective reference surface for a precise localization in vertical direction [1]. Evaluating the particle contrast for varying slit distances enables us to measure the scattering phase, amplitude, and consequently the z-position of individual particles without prior calibration of the particle contrast [2]. Precise knowledge of the nanoparticles' paths and surrounding potentials allows us to study confinement effects on Brownian motion and charge regulation at the participating interfaces. It further enables us to precisely trap and immobilize nanoparticles at a specific location on the substrate.

[1] P. Kukura et al., Nature Methods 6, 923-927 (2009).

[2] N. Mojarad et al., Optics Express 21, 8, 9377-9389 (2013).