Electronically excited C2 from laser photodissociated C60

Optical and X-ray Emission Spectroscopy of High-Power Laser-Induced Dielectric Breakdown in Molecular Gases and Their Mixtures

Large-scale plasma was created in molecular gases (CO, CO2, N2, H2O) and their mixtures by high-power laser-induced dielectric breakdown (LIDB). Compositions of the mixtures used are those suggested for the early earth's atmosphere of neutral and/or mildly reducing character. Time-integrated optical spectra emitted from the laser spark have been measured and analyzed. The spectra of the plasma generated in the CO-containing mixtures are dominated by emission of both C2 and CN radicals. A vibrational temperature of approximately 10(4) K was determined according to an intensity distribution in a vibronic structure of the CN (B2Sigma(+)u-X2Sigma(+)g) violet band. For comparison, the NH3-CH4-H2-H2O mixture has been irradiated as a model of the strongly reducing version of the early earth's atmosphere. In this mixture, excited CN seems to be significantly less abundant than C2. The LIDB experiments were in the molecular gases carried out not only in the static cell but also using a large, double stream pulse jet (gas puff target) placed in the vacuum interaction chamber. The obtained soft X-ray emission spectra indicate the presence of highly charged atomic ions in the hot core of high-power laser sparks.

Measurement and analysis of atomic and diatomic carbon spectra from laser ablation of graphite

Spectra from plasma produced by laser-induced breakdown of graphite were recorded and analyzed to increase our understanding of the way in which carbon nanoparticles are created during Nd:YAG laser ablation of graphite. The effects of various buffer gases were studied. Electron density and temperature were determined from spectra of the first and second ions of atomic carbon. The C2 Swan spectrum was also prominent in most of the measured spectra. Temperature was inferred from each experimental Swan spectrum by determination of the temperature for which a synthetic Swan spectrum best fitted, in the least-squares sense, the measured spectrum.