Experimental appraisal of the maximal-entropy theory of multiphoton ionization-fragmentation: The alternative ionization pathway test

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Abstract
An experimental test of the Silberstein–Levine (SL) maximal-entropy theory of multiphoton ionization-fragmentation has been devised and applied to a diverse group of polyatomic molecules. The MPI fragmentation pattern of a given compound is strongly dependent upon the laser wavelength (which governs the ’’pathway’’ to the continuum) and the laser power density (and pulse energy). Nevertheless, it is found possible to obtain similar fragmentation patterns at several wavelengths (i.e., via different pathways) by adjusting the laser power so as to excite the molecule/ion system to the same average value of internal energy 〈E〉. Data are presented for benzene, toluene, t-butylbenzene, triethylenediamine, quinuclidine, and iodomethane, all of which tend to confirm the major premise of the SL theory that the branching fraction pattern is governed by the single parameter 〈E〉.