We present experimental results on the photoluminescence (PL) of gas-suspended zinc oxide nanoclusters prepared during ablation of sintered ZnO targets by a pulsed ArF laser in the presence of oxygen ambient gas. The PL spectra in the UV spectral region correspond to the exciton recombination in the nanoclusters which are crystallized and cooled down to the temperature of the ambient gas in the ablation chamber. The time evolution of the spectra as well as their dependence on the ambient gas pressure are discussed.

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It is shown that, for plasmas in which electron-atom collisions dominate over other collision processes, the electron temperature can be derived from the density of metastable helium states measured with laser atomic absorption spectroscopy. The model describing the electron temperature as a function of the density of the metastable helium states is independent of the electron density and is valid for electron temperatures -10 eV and for electron densities to within an error of 20%. For an extended parameter range a more complex model, additionally requiring knowledge of the electron density, may be used.

Experiments in a low pressure glow discharge on gases of environmental relevance: CO2,CO y O2 are reported. We studied the various atomic processes: ionization, excitation and molecular dissociation with typical discharge parameters of p∼0.6 mbar, I≤ 0.1 A and V∼1100 Volts. We used visible and near UV spectroscopy to observe the emitted radiation on both electrodes on pure gases and hydrogen seeded mixtures. We also set up Langmuir probes in both electrodes.

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