Hannover 2016 – scientific programme
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MO: Fachverband Molekülphysik
MO 15: Femtosecond Spectroscopy 3
MO 15.7: Talk
Thursday, March 3, 2016, 12:45–13:00, f102
Temporal resolution in noisy-pulse transient absorption spectroscopy — •Kristina Meyer1, Niklas Müller1, Zuoye Liu1,2, and Thomas Pfeifer1 — 1Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany — 2School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
Pump--probe experiments with deuterium molecules using Free-Electron-Laser (FEL) pulses revealed molecular dynamics on time scales shorter than the average pulse duration [1]. This enhanced temporal resolution was explained by the partially coherent nature of the FEL pulses [2] and a temporal correlation between the pump and probe pulses. The average spectrum of the FEL pulses provides a coherence time much shorter than the average pulse duration, which is the ultimate limit of temporal resolution instead of the average duration of the noisy, fluctuating pulse shape. Here, we demonstrate the generalization of this noisy-pulse concept to time-resolved spectroscopy in complex systems in the liquid phase. Using a pulse shaper we generated partially coherent laser pulses in the visible to near-infrared range and performed transient-absorption measurements in a solution of the dye IR144 in methanol. Features occurring on time scales (~60 fs) shorter than the average pulse duration (300 fs) could be identified in the measured absorption spectra. Thus, we demonstrate the universality of the concept of achieving a temporal resolution beyond the average pulse duration with statistically fluctuating pulses. [1] Y. Jiang et al., PRA 81, 051402(R) (2010), [2] K. Meyer et al., PRL 108, 098302 (2012)