Effects of dual-pulse laser ablation

Krstulović, Nikša (2010) Effects of dual-pulse laser ablation. Doctoral thesis, Faculty of Science > Department of Physics.

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Abstract

In this work the effect of laser ablation which is induced with two, time separated, laser pulses was studied. As a main parameter in dual-pulse laser ablation delay time between the laser pulses τ appeared and it was scanned within interval 0 – 50 μs. Experiment is based on measurement of time-dependent absorption and emission from plasma plume of titanium ablated in vacuum in respect to τ. Absorption and emission spectra of Ti, and emission spectra of Ti+ were also measured as well as its temporal dependence. Absorption measurements were performed by means of cavity ring-down spectroscopy while emission measuremenst were performed by means of classical monocromator. Results shows many-fold increase of measured signal in dual-pulse in comparison to single-pulse laser ablation. For given temporal and spatial parameters absorption line profiles appeared doppler-splitted. It is indication of increased velocity component parellel to the target surface, i.e. increased phase explosion. The model was developed for simulation of absorption measurements. From the model parameters such are velocity distributuin of ablated species, or anisotropy function can be assessed. Otherway those parameters cannot be obtained directly from the experiment. Volumes, radii and depths of the craters induced by laser ablation were also measured in respect to τ. It was found that largest volumes were given for shorters τ when ablation threshold is lowest, except that for the shortest τ where screening effect dominates for the second pulse hence energy delievered to the target was decreased. Ti films deposited on si depend on τ and on regime of ablation (single or dual). The thickest and smoothed layer was made with τ = 2 μs.

Item Type: Thesis (Doctoral thesis)
Keywords: dual-pulse laser ablation ; laser ablation ; cavity ring-down spectroscopy ; laser-induced breakdown spectroscopy ; emission spectroscopy ; absorption profiles ; absorption spectra ; emission spectra ; laser drilling ; titanium
Supervisor: Milošević, Slobodan
Date: 18 June 2010
Number of Pages: 233
Subjects: NATURAL SCIENCES > Physics
Divisions: Faculty of Science > Department of Physics
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 22 Dec 2013 21:55
Last Modified: 22 Dec 2013 21:55
URI: http://digre.pmf.unizg.hr/id/eprint/52

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