Hannover 2016 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 18: The Modelling of Molecular Dynamics

MO 18.5: Vortrag

Donnerstag, 3. März 2016, 15:30–15:45, f142

Tuning the nonradiative lifetime via excitonic interaction — •Alan Celestino and Alexander Eisfeld — MPIPKS, Dresden, Germany

Nonradiative electronic transitions are typical in many molecules. These transitions can occur in the pico- or even femtosecond scale. For being able to occur so rapidly, nonradiative transitions can also sup- press the slower spontaneous emission in certain molecules. For these molecules, controlling the nonradiative lifetime equals controlling the lifetime of an electronic excitation. Depending on the application in mind one would like to make this lifetime longer or shorter. Aggregated molecules interact and both their radiative and nonradiative lifetimes are in general changed by this interaction. In the present work we study the influence of transition dipole-dipole interaction (excitonic interaction) between molecules on their nonradiative lifetime. As an example, we consider the dynamics of Frenkel excitons in a homod- imer. The monomer is a two electronic level system coupled to nuclear vibrations. We consider the nonradiative channel to be well localized in the nuclear space. We calculate numerically the nonradiative lifetime of the dimer for different excitonic interaction strengths, positions of the nonradiative coupling and nuclear relaxation times. Using a Born- Oppenheimer approximation in the dimer level, we obtain the relevant dimeric potential surfaces. By using them, we can explain the direction of the changes in lifetime induced by excitonic interaction depending on the nonradiative channel position. For strong excitonic interaction, we can quantitatively predict the nonradiative lifetime.