Stuttgart 2012 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 59: Ultrakurze Laserpulse

Q 59.3: Vortrag

Freitag, 16. März 2012, 11:00–11:15, V38.04

A Farewell to Laser Flash Photolysis: Transient Spectroscopy Covering Three Octaves and 11 Orders of Magnitude in Time — •Maxmimilian Bradler, Christoph Grill, Christian Sailer, Daniel Herrmann, Igor Pugliesi, and Eberhard Riedle — BioMolekulare Optik, LMU München

We present transient UV-visible-NIR spectroscopy that can be used for the everyday analysis of dynamical and kinetic processes over an unprecedented temporal and spectral range. We achieve a 50 fs temporal resolution covering 195 to 5000 nm excitation without gap and 245 to 1600 nm detection. The pump for fs to few ns measurements is based on a NOPA operated at kHz repetition rate and nonlinear optics for frequency conversion. As probe light fs continua generated in bulk materials are utilized. With 775 nm pumping from the Ti:Sa amplifier operated at 1 kHz a probe range from 285 to 730 nm is available. The range down to 245 nm can be accessed with SHG pumping. The range up to the cut-off of silicon based detectors is covered by a continuum pumped by 1250 nm pulses. For the longest wavelength range out to 1600 nm the continuum-pump is tuned to 1800 nm and a InGaAs array used for detection. To cover the time range beyond single nanoseconds we use a synchronized ns OPO (tunable from 210 to 2600 nm) for excitation. The jitter of this light source is less than 200 ps, and its pulses are about 2.7 ns long. Switching the pump pulse allows us to cover in total the temporal range from femtoseconds to about one millisecond. The probe wavelength is reproducible to about 0.1 nm and this allows even for the observation of extremely small spectral shifts.