Laser ion kinetics: set-up and application of a single-shot femtosecond pump-probe technique

In this contribution the first measurements of a single-shot femtosecond la ser pump-probe technique are reported. The technique is based on counter-pr opagating femtosecond laser pulses in a supersonic beam of a low density of sample molecules and simultaneous probe detection by ion or fragment-ion f ormation through a reflectron time-of-flight mass spectrometer. It will be shown that the range of the pump-probe delays covers the time span between 100 fs and 10ps depending on the pulse width of the laser used and the stab ility of the volt ages of the mass spectrometer. The application of this te chnique to organometallic compounds as well as to medium-sized organic mole cules reveals some insight into the electron-transfer process during ioniza tion through a 1+1 multi-photon absorption procedure. Furthermore it is dem onstrated that this technique is also applicable to the investigation of ul tra-fast isomerization and fragmentation processes. As an example the resul ts of the processes within iron pentacarbonyl and substituted benzalacetone s are reported.