Laser ion kinetics: dynamics of intramolecular reactions in substituted benzalacetones

Measurements of a single shot femtosecond laser pump-probe technique on sub stituted benzalacetones are reported. The technique is based on counter pro pagating femtosecond laser pulses in a supersonic beam of low density of sa mple molecules and simultaneous probe detection by ion or fragment ion form ation through a reflectron time-of-flight mass spectrometer, It will be sho wn that the range of the pump-probe delays covers the time span between 100 fs and 10 ps depending on the pulse width of the laser used and the stabil ity of the voltages of the mass spectrometer, The application of this techn ique to medium-sized organic molecules reveals some insight into the electr on transfer process during ionisation through a 1 + 1 multi-photon absorpti on procedure. Furthermore it is demonstrated that this technique is also ap plicable to the investigation of ultra-fast isomerisation and fragmentation processes.