THE APPLICATION OF RESONANT MULTIPHOTON IONIZATION BY SUBPICOSECOND LASER-PULSES FOR ANALYTICAL LASER MASS-SPECTROMETRY

Resonance-enhanced multiphoton ionization (REMPI) offers a number of a dvantageous features for the analysis of complex mixtures, e.g. the ab ility to ionize preselected compounds and to control the degree of fra gmentation, and, for a large number of substances, a high ionization e fficiency. These features require that the excited molecular state(s) involved in the MPI process are not significantly depleted during the duration of the laser pulse. For several groups of environmentally imp ortant molecules, such as metal organic compounds, this is not the cas e. In this work it is demonstrated that, for a number of such molecule s, the interesting features of REMPI for analysis can largely be regai ned, for quickly relaxing systems, by the application of ultra-short l aser pulses. (C) 1997 by John Wiley & Sons, Ltd.