Collisional activation of N2O decomposition and CO oxidation reactions on isolated rhodium clusters.

The reactions of nitrous oxide decorated rhodium clusters, RhnN2O(+) (n = 5, 6), have been studied by Fourier transform ion cyclotron resonance mass spectrometry. Collision induced dissociation with Ar is shown to lead to one of two processes; desorption of the intact N2O moiety (indicating molecular adsorption in the parent cluster) or N2O decomposition liberating molecular nitrogen with the latter becoming increasingly dominant at higher collision energies. Consistent with the results of earlier studies, which employed infrared excitation [Hermes, A. C.; et al. J. Phys. Chem. Lett. 2011, 2, 3053], Rh5ON2O(+) is observed to behave qualitatively differently to Rh5N2O(+) with decomposition of the nitrous oxide dominating the chemistry of the former. In other experiments, the reactivity of RhnN2O(+) clusters with CO has been studied. Chemisorption of (13)CO is calculated to deposit ca. 2 eV into the parent cluster, initiating a range of chemical processes on the cluster surface, which are fit to a simple reaction mechanism. Clear differences are again observed in the reaction branching ratios for Rh5N2O(+) and Rh6N2O(+) parent cluster ions. For the n = 5 cluster, the combined N2O reduction/CO oxidation is the most significant reaction channel, while the n = 6 cluster preferentially is oxidized to Rh6O(+) with loss of N2 and CO. Even larger differences are observed in the reactions of the N2O decorated cluster oxides, RhnON2O(+), for which more reaction possibilities arise. The results of all studies are discussed in relation to infrared driven processes on the same parent cluster species [Hamilton, S. M.; et al. J. Am. Chem. Soc. 2010, 132, 1448; J. Phys. Chem. A, 2011, 115, 2489]

2 còpies d'Informació sobre els terminis i lloc de presentació de sol·licituds d'Estades Temporals de Científics i Tecnòlegs Estrangers a Espanya (Modalitats A i B)

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Generation of C6H4+ by laser vaporization of magnesium with o-C6H4F2 in argon carrier gas

A route to efficient generation of C6H4+, potentially the benzyne radical cation, is presented. Laser vaporization of Mg+. and supersonic expansion in helium doped with o-, m-, or p-C6H4F2 yields, among other ions, o-, m-, p-C6H4F2Mg+.. complexes, but no C6H4+.. Collision-induced dissociation experiments show that the o-C6H4F2Mg+. complex can be converted into C6H4+. in a mildly energetic collision, with a center-of-mass energy around 1-2 eV. These conditions can also be reached in the ion source when argon is used as a carrier gas. In this way, mass spectra containing the desired m/z 76 peak, i.e. C6H4+., are obtained. Copyright (C) 2004 John Wiley Sons, Ltd