Paper
20 September 2004 Excimer laser ablation: energy or power density? A different approach
Lucien Diego Laude, Claudio Dicara, Konstantin Kolev, Helmut Schillinger
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Abstract
In all excimer laser irradiation data, the induced laser ablation process is constantly referred to an energy density (fluence) and, eventually, to a fluence threshold that sets the onset of matter emission. In the work presented here, ablation experiments have been performed on a specific class of ceramic (sialon) with two excimer sources A and B that differ in their respective time-profiles, with a full pulse width of either (A) 23 or (B) 44 ns. Working with these sources at identical fluences and number of pulses, products of irradiation may differ drastically. In particular, it is observed that an irreversible surface decomposition may be achieved with laser A at a given threshold fluence, not with laser B that requires a higher fluence. Results are analyzed and interpreted taking into account the time dependence of the laser emission and its consequences in terms of photon-electron interactions at the material surface. Differing strongly from existing moels of ablation, a two-step model is presented that incorporates (1) creation of a free-electron gas at the material surface and (2) its subsequent photoemission giving rise to surface ionization and structural instability. Results are discussed in the light of that model. In particular, a distinct advantage is given to short pulse excimer sources in their ability to modify surface properties at lesser fluences and with reduced heat generation, as compared to longer pulse sources.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Lucien Diego Laude, Claudio Dicara, Konstantin Kolev, and Helmut Schillinger "Excimer laser ablation: energy or power density? A different approach", Proc. SPIE 5448, High-Power Laser Ablation V, (20 September 2004); https://doi.org/10.1117/12.563197
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Cited by 2 scholarly publications.
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KEYWORDS
Electrons

Excimer lasers

Laser ablation

Chemical species

Absorption

Metals

Ceramics

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