Depth-resolved analysis by laser-induced breakdown spectrometry at reduced pressure
✍ Scribed by Vadillo, J. M.; Fern�ndez Romero, J. M.; Rodr�guez, C.; Laserna, J. J.
- Book ID
- 101222807
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 165 KB
- Volume
- 26
- Category
- Article
- ISSN
- 0142-2421
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✦ Synopsis
The 581 nm output from a dye laser in a Ñuence range between 2.86 and 11.47 J cm-2 was used to ablate pure Zn and Fe foils. The average ablation rate (AAR, lm per shot) was calculated for di †erent experimental variables (bu †er gas, pressure, laser Ñuence and focal conditions). Deposition of previously ablated material in the ablation crater results in large variation of the observed AAR values. This e †ect was observed in air and argon bu †er gases at atmospheric pressure. The situation is largely alleviated at reduced pressure due to free expansion of the ablated material. Under these circumstances the capability of laser-induced plasmas to resolve interfacial structures is improved. The e †ect on depth-resolved studies was checked with a commercial Zn-coated steel sample. Due to the Gaussian-like energy distribution of the incident laser beam, the material is ablated to produce a conical crater. This fact ensures that the Zn signal remains for a longer time because the ablated region spreads over the edge gradually. At low pressure the emission peaks are better deÐned and the background becomes Ñat. However, these conditions produce also the lowest net intensities and some peaks are not detected. An Ar atmosphere produces more intense spectral lines at both pressure levels. Best analytical results were obtained at reduced pressure, with a slight improvement in depth resolution in the presence of Ar.
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