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Articles you may be interested inVibrational mode and collision energy effects on reaction of H 2 CO + with C 2 H 2 : Charge state competition and the role of Franck-Condon factors in endoergic charge transfer Probes of spin conservation in heavy metal reactions: Experimental and theoretical studies of the reactions of Re + with H 2 , D 2 , and HD Theoretical study of the reactions of Ar + +H 2 and Ar + +HD using the trajectory surface hopping method We present cross sections as a function of the collision energy for the bond-forming reactions of argon dications with oxygen molecules, producing ArO 2ϩ ϩO and ArO ϩ ϩO ϩ , respectively. Both the reactions are exothermic, and have cross sections much smaller than those of the competitive charge-transfer processes. The low-lying electronic states of ArO 2ϩ have been calculated at the MR-AQCC/cc-pV5Z level. In contrast to previous results we found that the ground 3 ⌺ Ϫ state has a local minimum. However, the estimated lifetime of this metastable state is too short to be detected in our setup. Thus the observed ArO 2ϩ ions must be in the higher-lying 1 ⌬ or 1 ⌺ ϩ states.

Here, we investigate the effect of the structure (generation) and nature of the surface groups of different polyamidoamine (PAMAM) dendrimers on electron-mediated dissociation, either electron capture dissociation (ECD) or electron detachment dissociation (EDD), and compare the fragmentation with that observed in collision-induced dissociation (CID). ECD and EDD of the PAMAM dendrimers resulted in simple mass spectra, which are straightforward to interpret, whereas CID produced complex mass spectra. The results show that electron-mediated dissociation (ECD and EDD) of PAMAM dendrimers does not depend on the nature of the surface group but tends to occur within the innermost generations. CID of the PAMAM dendrimers showed a strong dependence on the nature of the surface group and occurred mostly in the outer generation. The results demonstrate the potential utility of ECD and EDD as a tool for the structural analysis of PAMAM dendrimers.

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EID tandem mass spectrometry of singly-charged electrosprayed ions of octaethylporphyrin (OEP) and its iron(III) complex results in ionisation to give doubly-charged precursor and fragment ions. Singly-charged fragments are also observed. EID fragmentation differs significantly to that observed in electron ionisation mass spectrometry.