Zur Startseite von DrArbeit.de,
der deutschlandweiten Stellenbörse für Diplomarbeiten und Doktorarbeiten


Archiv - Stellenangebot


Dies ist ein Angebot aus der Datenbank von DrArbeit.de

Um die Datenbank komfortabel nach weiteren Angeboten durchsuchen zu können, klicken Sie einfach oben oder hier.

Archiv-Übersicht     Angebot Nr. 13292

Angebotsdatum: 11. Februar 2019
Art der Stelle: Diplomarbeit
Fachgebiet: Physik > Angewandte Physik
Titel des Themas: Surface height profile imaging with Optically Trapped Spheres

Institut: Universität Freiburg, Labor für Bio- und Nano-Photonik, IMTEK
Dr. rer. nat. Felix Jünger
Georges-Köhler-Allee 102
79110 Freiburg
Tel.:    Fax.:
Bundesland: Baden-Württemberg
Homepage: http://www.imtek.de/professuren/bnp/stellen
E-Mail Kontakt: mail

Beschreibung: Background:
Optical traps play an increasing role in the bio-nano-sciences due to their ability to flexibly apply forces on tiny structures in fluid environments. Combined with particle tracking techniques they allow sensing miniscule forces exerted on these structures. Similar to atomic force microscopy (AFM), but much more sensitive, an optically trapped probe can be scanned across a structured surface to measure the height profile from the displacements of the probe.
We use a combination of a time-shared twin-optical trap and nanometer-precise 3D interferometric particle tracking reliable height-profiling and surface imaging, with a spatial resolution below the diffraction limit. The technique exploits the high energy thermal position fluctuations of the trapped probe, leading to a sampling of the surface 5000 times softer than in AFM. The measured height and force profiles from test structures and helicobacter cells illustrate the potential to uncover specific properties of hard and soft surfaces. (see Friedrich & Rohrbach in Nature Nanotechn., 2015).

Research goal: Further increasing the spatial resolution
The smaller the size of the trapped sphere, the smaller the structures at the surface that can be probed. The achievable spatial resolution depends in a first approximation linearly on the probe diameter and its polarizability. We want to use probes with diameters below 100 nm and with a high polarizability, such as small metal or semiconductor beads. At the same time, the trap stiffness must be increased and the diffusion volume of the probe decreased. Here, the right laser wavelength plays must be found for both trapping stability and tracking sensitivity. In addition, other characteristics of the probe’s thermal motion such as 3D fluctuation widths or temporal correlations shall be explored to uncover further structural information of the sample.

Research project:
The project parts require experimental and construction work, as well as computer simulations and theory to work out the principles and to find the best research strategy for solving the above questions.

We are looking forward to answering your questions!
Anfangsdatum: 11. Februar 2019
Geschätzte Dauer: 6-12 months