Bayreuth 1998 – scientific programme

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CP: Chemische Physik

CP 11: Einzelteilchenspektroskopie

CP 11.11: Poster

Tuesday, March 10, 1998, 18:00–20:00, P1

The influence of oxygen on single molecule blinking — •O. Panzer, W. Göhde, U.C. Fischer, and H. Fuchs — Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Straße 10, D-48149 Münster

The fluorescence of single molecules often shows unsteady on–off transitions (”blinking”).
We observed the blinking of single Terrylendiimide (TDI) molecules absorbed on a glass surface by means of confocal fluorescence microscopy.Our special interest was to examine the influence of ambient oxygen on the kinetics of those on–off transitions at room temperature.
The on times during which the fluorescence is above a certain threshold are prolonged significantly in nitrogen compared to those in ambient air.The off times–during which the fluorescence is below the same threshold–are not affected.
Also fluorescence measurements were made on a large ensemble of TDI molecules.Reverible changes of the fluorescence are induced by flushing alternately with nitrogen and air.
It is shown that a simple phenomenological model consisting of a fluorescing and a non fluorescing state for the molecule match the observations on the ensemble as well as those on the single molecules.
The exact physical and chemical processes responsible for blinking are still unclear.