SIMULTANEOUS DETERMINATION OF ABSORPTION CROSS-SECTIONS AND DECAY-RATE CONSTANTS BY QUANTITATIVE LASER MASS-SPECTROMETRY

A method is described that allows the simultaneous measurement of the transition cross sections between the molecular states involved in a m ultiphoton process and the decay rate constants for the intermediate l evels involved. The technique is based on the quantitative determinati on of the multiphoton ionization efficiency as a function of the laser intensity applied. From these values the cross sections and rate cons tants are extracted by an algorithm using multiple non-linear regressi on. Several examples are discussed and compared to values obtained wit h conventional techniques. (C) 1998 Elsevier Science B.V.