Abstract Pulsed laser ablation of Silver and Gold targets, immersed in a polymeric solution of Polyvinylpyrrolidone (PVP), is used to generate colloids and composite metal-polymer. Solutions of PVP in deionized water at different concentrations are employed. Two PVP number average molecular weights were considered, 10000 g/mol and 55000 g/mol. The high purity targets are irradiated between 20 min and40 min with the third harmonic (THG) ( λ = 335 nm) of a Nd:YAG laser operating at a rate of 10 Hz with pulses of 8 ns. Optical spectroscopy in UV and vis regions, Scanning Electron Microscopy (SEM), High Resolution Scanning Electron Microscopy (HR-SEM) and X-Ray are used to identify and determine the shape and size of the produced particles. Very stable sub-micrometric spherical particles for Au/PVP y Ag/PVP samples are obtained with diameters of 0.72 μ m y 0.40 μm, respectively. The preparation of colloids is performed in one step and no surfactant or dispersing agent is used in this process.

The propagation and expansion of the plasma produced by a coaxial plasma gun is evaluated simultaneously using a laser beam deflection technique and a Langmuir double probe. The first method is very sensitive to the time and space dependent gradients produced by the pulsed plasma, and it is applied to measure the resulting beam deflection over a He-Ne laser beam that is placed perpendicular to the propagation axis. The system with a quadrature detector has a rise time response of 10 ns and a resolution of 2 µrad. The Langmuir double probe is used along the axis and allows us to measure the time of flight under diverse plasmas conditions. We present comparative measurements for Nitrogen and Helium background gases from 50 to 500 mTorr, in a 50 cm long and 10 cm diameter chamber.

La propagación de un pulso de plasma generado en un acelerador coaxial de 4 kJ, es detectada simultáneamente a través de una sonda doble de Langmuir y un sistema óptico de deflexión láser. La señal de deflexión sobre un haz láser de He-Ne, colocado perpendicularmente al eje de propagación, es una medida de los altos gradientes espacio-temporales generados por el pulso de plasma. Para esto se utiliza un detector de cuadratura de respuesta rápida (10 ns), que permite medir desviaciones angulares del haz de hasta 2 µrad. La sonda de Langmuir se utiliza para medir los tiempos de vuelo del plasma a lo largo del eje bajo diferentes condiciones del gas de fondo. El estudio comparativo de estas dos señales es realizado en ambientes de nitrógeno y helio a presiones de 50 a 500 mTorr sobre una cámara de expansión de 50 cm de longitud y 10 cm de diámetro.

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.