Different techniques are applied in order to obtain information about ultrafast molecular and reaction dynamics. Femtosecond time-resolved pump-probe spectroscopy is used to investigate the dissociation reaction of NAI molecules. Starting from free NaI molecules, the environment is changed to solution-like conditions adding rare gas with different pressures. Femtosecond time-resolved degenerate four-wave mixing (DFWM) spectroscopy is performed in order to investigate molecular dynamics in iodine molecules in the gas phase. Depending on the timing of the laser pulses different dynamics are reflected in the DFWM transient signal. By the use of time evolution diagrams, the varying contribution of ground and excited-state dynamics can be explained conclusively. Supersonic jet-cooled potassium dimers are investigated in their electronic ground state by a femtosecond pump-probe experiment. The ground state vibrational wave packets are created by a stimulated Raman pumping process and selectively interrogated by resonance enhanced three photon ionization.
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