アイテム詳細

要旨

In this thesis, the role of phase-control in time-resolved spectroscopy was investigated. In the first part, measuremets and simulations about autocorrelations with laser pulses modified by the partial-coherence-method were performed under laboratory conditions. This was motivated by measurements at a free-electron-laser (FEL) [17], because a better resolution than the one predicted by the mean pulse duration were measured. Within the scope of this thesis work, the measured structures at the FEL were also observed under laboratory conditions using statistical laser pulse shaping in the time domain. In the second part of this thesis, modifications in a measured absorption spectrum of the dye IR-144 [15] were modelled and interpreted. The many absorption lines of the dye were estimated by the free-electron-molecular-orbital-approximation and the infrared-active modes. The essential part of this thesis is the model and simulation of the modifications in the absorption spectra: A first laser pulse induces transitions into excited states. After a certain time, in which the dipole response performs a damped oscillation, a second laser pulse shifts the transition frequency during the interaction time with the second laser pulse. Due to the modified transition frequencies an additional phase is imprinted on the dipole response. It is shown that the measured modifications can be described by this toy model. The measured and simulated results were compared to each other at different time delays between the two laser pulses and different intensities of the second laser pulse.