Resumo

FLORES, Teresa et al. Laser-induced breakdown spectroscopy analysis with multi-pulse excitation for ablation process of tuna areolas. Nova scientia [online]. 2010, vol.2, n.4, pp.16-32. ISSN 2007-0705.

Introduction: The Laser-Induced Breakdown Spectroscopy technique (LIBS), has important advantages over other analytical techniques. For example, the sample requires no preparation may be in solid, liquid, or gas phase and have any shape and size, it requires a minimal amount of material and finally, the analysis is performed in real time. These advantages make possible realtime tracking of a laser ablation process, even for samples of complex composition. For monitoring an industrial process, this tool would be most appropriate if you have a calibration of equipment and a particular defined protocol. In this work, we show the results for LIBS analysis performed for the case of laser ablation of Tuna areolas (fruit of the Opuntia ficus-indica). Method: The LIBS analysis of tuna samples takes place, both in the areola and in the cortex. For the plasma excitation we uses a Nd: YAG laser with special Q:Switch scheme: The pulse train emission regime. In order to guarantee the lines recognition in the LIBS spectra, before experiments widh samples, we takes the spectrum of well known composition standarts, establishing a protocol for the interpretation of spectra. Results: A clear reading for the H line located at 656.2 nm was obtained. A simple protocol was established for the spectra interpretation, which allowed the identification of 49 characteristic peaks. Finally, the composition to the cortex and the areola were determined and carried out a qualitative comparison between them. Discussion or Conclusion: The results shows that the laser excitation in pulse train form, understood as a particular form of Q: Switch regime, provides an intense plasma emission and efficient elements determination, with adequate signal to noise ratio. Moreover, it is possible to identify compositional differences between crust and areola, which can permits to track the laser ablation of areolas process in a simple way.

Palavras-chave : opuntia; plasma; láser; LIBS.

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