Dresden 2014 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
DF: Fachverband Dielektrische Festkörper
DF 25: Glasses and Glass Transition II (Joint Session with CPP and DY)
DF 25.6: Vortrag
Donnerstag, 3. April 2014, 17:00–17:15, ZEU 114
Single molecule diffusion measurements in highly viscous media — •Dominik Wöll1,2 and Maren Dill2 — 1Zukunftskolleg, Universität Konstanz, D-78457 Konstanz — 2Fachbereich Chemie, Universität Konstanz, D-78457 Konstanz
Single molecule diffusion measurements in highly viscous media require a method which can readily detect very low diffusion coefficients. Single molecule fluorescence tracking typically becomes rather unreliable for diffusion coefficients below 10−18 m2 s−1 due to the limited accuracy in determining single molecule positions of a few nanometres and the need for a very high stability of the optical system, even for long-time measurements of several hours. We developed a photocleavable energy transfer dyad which, so far, has allowed us to extend the range of single molecule (pair) diffusion measurements by three orders of magnitude and to determine slow single molecule motion in polymer films in close vicinity to their glass transition temperature. As a FRET pair, we used a perylene and a terrylene diimide derivative, two very efficient and stable fluorophores ideal for single molecule fluorescence spectroscopy. A phenacyl derivative was chosen as the photolabile moiety which could be cleaved with UV light. Initially, the two fluorophores are covalently bound to each other and move correlated before they are cleaved by a UV light pulse and their diffusive separation gives access to low diffusion coefficients of down to 10−21 m2 s−1 and beyond.