Hamburg 2009 – scientific programme

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SYSM: Single Molecule Spectroscopy of Nanoobjects

SYSM 3: Single Molecule Spectroscopy of Nanoobjects III

SYSM 3.3: Invited Talk

Thursday, March 5, 2009, 17:50–18:30, VMP 8 HS

Femtosecond Time-Resolved Spectroscopy of Single Molecules — •Richard Hildner¹, Daan Brinks¹, and Niek F. van Hulst^1,2 — ¹ICFO - Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain — ²ICREA - Institucio Catalana de Recerca i Estudis Avancats, 08015 Barcelona, Spain

We present a study of the femtosecond dynamics of single molecules embedded in an inert polymer matrix at room temperature employing a fluorescence detected double pulse excitation scheme. By controlling the delay time between the excitation pulses as well as the relative phase between the electric fields of the pulses we are able to manipulate the excited state population probabilities of single molecules. An analysis of these data based on the optical Bloch equations for two- and three-level systems allows to retrieve the dephasing time of single molecules directly in the time domain. In addition the transition dipole moments (absorption cross sections) and thus the Rabi-frequencies can be determined from these data. We found dephasing times between 25 -- 50 fs and the transition dipole moments were distributed between 0.8 and 16 D.