Triplet solvation dynamics in supercooled hydrogen bonding liquids in hard and soft confinements

Principle

As in dielectric spectroscopy (DS), triplet solvation dynamics (TSD) measures the reorientation of the molecular dipoles of a liquid as a response to an electric field. The difference lies in the generation of the electric field. Instead of applying a macroscopic electric field over the entire sample, the field is generated locally in the sample itself. This is done by adding a dye to the sample in a very low concentration. When pumping the dye with a pulsed UV Laser, it can be excited to a long-lived triplet state. Since the dipole moment of the triplet state differs from the ground state dipole moment, the surrounding liquid molecules start to reorient in response to the changed electric field of the dye molecule. Due to the relaxation of the surrounding liquid, a Stokes shift of the emission wavelength of the dye occurs, which can be measured in the time range from 1 ms to 1 s by time-resolved optical spectroscopy [1]. The spatial range of TSD is limited to the first solvation shell around the dye, making it possible to measure the relaxation dynamics locally in confinements of a few nanometres.

Schematic of Solvation Dynamics: dye molecule (red), solvation shell (dark blue), molecular dipoles (green)

References

[1] Richert, R. (2000). Triplet state solvation dynamics: Basics and applications. The Journal of Chemical Physics, 113 (19), 8404. doi:10.1063/1.1319174

Kontakt

Prof. Dr. Thomas Walther

Laser und Quantenoptik
Institut für Angewandte Physik
Fachbereich 05 - Physik
Technische Universität Darmstadt
Schlossgartenstr. 7
D-64289 Darmstadt

+49 6151 16-20831 (Sekretariat)

+49 6151 16-20834

Thomas.Walther@physik.tu-...

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