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Ion-molecule reactions involving metallic species play a central role in the chemistry of planetary ionospheres and in many combustion processes. The kinetics of the Ca(+) + N(2)O --> CaO(+) + N(2) reaction was studied by the pulsed multiphoton dissociation at 193 nm of organo-calcium vapor in the presence of N(2)O, followed by time-resolved laser-induced fluorescence spectroscopy of Ca(+) at 393.37 nm (4(2)P(3/2) <-- 4(2)S(1/2)). This yielded k(188-1207 K) = 5.45 x 10(-11) (T/300 K)(0.53) exp(282 K/T) cm(3) molecule(-1) s(-1), with an estimated accuracy of +/-13% (188-600 K) and +/-27% (600-1207 K). The temperature dependence of this barrierless reaction, with a minimum in the rate coefficient between 400 and 600 K, appears to be explained by the role of N(2)O vibrational excitation. This is examined using a classical trajectory treatment on a potential energy surface calculated at the B3LYP/6-311+g(2d,p) level of theory.

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A new technique of metal nanopowder production and in situ coating using a microarc discharge is proposed. The feasibility of this method is demonstrated and preliminary results are presented. The microarc discharge was operated at 1 atm in both pure Ar and natural gas environments. Respectively, aluminium nanoparticles without and with ∼1 nm thick carbon surface coating were obtained. The morphology and structures of the nanoparticles were studied using a transmission electron microscope (TEM), and size distribution of the coated particles was determined from the TEM image analyses. It was found that the sizes of the produced carbon-coated aluminium particles were well described by a lognormal distribution with the geometrical mean size of 22.7 nm and standard deviation of 1.35.