engleski

Laser plasmas produced in various environments studied by optical emission spectroscopy

Pulsed laser ablation is the process which occurs when laser pulse hits the solid target and ablates material from target surface, due to various energy transfer processes as photodissociation, target heating, electron- phonon coupling and Coulomb repulsion between positive ions remained after electron ejection. The latter results in explosion (ablation) of target material which is ejected in the form of the hot plasma while simultaneously crater is formed at the target surface. If ablation is performed in liquid, liquid pressure ensures that plasma is confined in small space and exists in dynamic state of plasma plume. This process is called Pulsed laser ablation in liquid and presents "green technique" for nanoparticle production. Optical emission spectroscopy (OES) is technique that can provide us information about dynamics and related processes in laser produced plasmas. From Planck's distribution fit it's possible to determine the temperature of target during laser ablation. From line spectra and Boltzmann fit one can determine temperatures of ablated species in plasma plume. In this paper, OES is made on laser produced hot plasmas at three different environments above target - vacuum, air and water. Laser ablation is performed with Nd:YAG laser with fundamental wavelength 1064 nm. Laser operates at repetition frequency of 5Hz and pulse duration is 4ns. Analysed ablated targets are Au, Ag, Cu, ZnO and TiO2. Variations of pulse energies (300 mJ, 200 mJ, 100 mJ) and pulse wavelengths (1064 nm, 532 nm, 266 nm) are used for additional comparison.

Laser produced plasmas, optical emission spectroscopy

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