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The recent addition of (i) a third sector field to our two sector field mass spectrometer (resulting in a BE1E2 field configuration) and of (ii) a high performance electron gun enables us now to study in detail the time dependence of the kinetic energy release distribution (KERD) over a relatively wide range of cluster ion lifetimes. Using this newly constructed device we have studied here for the first time KERDs and deduced binding energies BEs (using finite heat bath theory) of large rare gas cluster ions (an upper size limit in earlier studies arose from the fact that different naturally occurring isotopes will contribute to a chosen metastable peak when the size exceeds a certain value) and in addition of fullerene ions smaller and larger than C60+ (here again contaminating coincidences did not allow such studies earlier). Moreover, high precision KERD measurements for the decay of rare gas dimer ions in conjunction with model calculations (using recently calculated potential energy curves for the rare gas dimer ions) also enable us to obtain information on the dynamics and the mechanisms of the underlying spontaneous decay reactions Rg2+∗ → Rg+ + Rg. In addition, we are also reporting here a novel method (unified breakdown graph method) to determine cluster ion binding energies using a recently constructed tandem mass spectrometer BESTOF allowing us to measure fragmentation patterns arising from the unimolecular decay of molecular cluster ions induced by surface collisions. The fragmentation and reaction patterns of protonated ethanol cluster ions investigated here clearly demonstrate in contrast to some of the earlier cluster ion studies that unimolecular dissociation kinetics determines the formation of product ions in the surface-induced decomposition. [ABSTRACT FROM AUTHOR]

Abstract: We have measured kinetic-energy-release distributions (KERD) for spontaneous dissociation of electronically excited dimer ions of krypton and xenon, formed by electron impact ionization of neutral precursors. The data cannot be reconciled by decay of the strongly bound II(1/2u) state that successfully explains dissociation of and . Instead, the KERD is dominated by contributions from the weakly bound II(1/2g) state that has so far escaped a convincing experimental characterization. The present data can be utilized to assess the accuracy of ab initio potential energy curves of this state. [Copyright &y& Elsevier]

Abstract: Doubly charged ions produced by electron impact ionization of toluene undergo metastable decomposition. We have determined decay channels for and the average kinetic energy release (KER) by applying the MIKE scan technique. We observe several reactions that have not been reported previously, including H2 elimination from . The KER distribution for H2 loss shows no evidence for a reverse barrier. The average KER is <0.1 eV; it exhibits a distinct time dependence and isotope effect. On the other hand, some charge separation reactions reported previously in the literature are likely due to isotopic interference. [Copyright &y& Elsevier]