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

Experimental Setup (Advanced)

The accessible time range is limited by two different processes. At the long end it is limited only by the lifetime of the excited state. At the short end it is limited by the fact that a direct population of the triplet state from the singlet ground state is prohibited for optical excitation.

Generalized excitation scheme for Triplet Solvation Dynamics

This can be overcome by employing a two-photon excitation. Two possible techniques are the Stimulated Emission Pumping (SEP) and the STimulated Raman Adiabatic Passage (STIRAP) . For both excitation schemes it is necessary that the two laser pulses have a low timing jitter and a small spectral bandwidth. Therefore, we are building up a regenerative Ti:Sapphire amplifier, which allows the synchronous amplification of two different wavelengths [2]. The seed lasers for the amplifier consist of two external cavity diode lasers (ECDL), which run at 940nm and 960nm. After the amplification, the 960nm radiation is frequency tripled to 320nm. The timing between the two pulses is tuned by a simple optical delay line. The two-photon excitation promises both higher signal-to-noise and the observation of TSD at timescales far below 1ms.

Advanced experimental setup for two-photon excitation

References

[1] Bergmann, K., Theuer, H., & Shore, B. (1998). Coherent population transfer among quantum states of atoms and molecules. Opens external link in new windowReviews of Modern Physics, 70(3), 1003–1025. 

[2] Tian, C., Walther, T., Nicolaescu, R., Pan, X. J., Liao, Y., & Fry, E. S. (1999). Synchronous, dual-wavelength, injection-seeded amplification of 5-ns pulses in a flash-lamp-pumped Ti:sapphire laser. Optics Letters, 24(21), 1496–1498.

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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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