Laser induced breakdown spectroscopy (LIBS) applied to stratigrafic elemental analysis and optical coherence tomography (OCT) to damage determination of cultural heritage brazilian coins
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2009
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SPIE EUROPE: OPTICAL METROLOGY
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This work presents a compositional characterization of 1939’s Thousand “Réis” and 1945’s One “Cruzeiro” Brazilian
coins, forged on aluminum bronze alloy.
The coins were irradiated by a Q-switched Nd:YAG laser with 4 ns pulse width and energy of 25 mJ emitting at 1064
nm reaching 3.1010Wcm-2 (assured stoichiometric ablation condition), forming a plasma in a small fraction of the coin.
The plasma emission was collected by an optical fiber system connected to an Echelle spectrometer. The capability of
LIBS to remove small fraction of material was exploited and the coins were analyzed ablating layer by layer from patina
to the bulk.
The experimental conditions to assure reproductivity were determined by evaluation of three plasma paramethers:
ionization temperature using Saha-Boltzmann plot, excitation temperature using Boltzmann plot, plasma density using
Saha-Boltzmann plot and Stark broadening.
The Calibration-Free LIBS technique was applied to both coins and the analytical determination of elemental
composition was employed. In order confirm the Edict Law elemental composition the results were corroborated by
Neutron Activation Analysis (NAA). In both cases the results determined by CF-LIBS agreed to with the Edict Law and
NAA determination. Besides the major components for the bronze alloy some other impurities were observed.
Finally, in order to determine the coin damage made by the laser, the OCT (Optical Coherence Tomography) technique
was used. After tree pulses of laser 54µg of coin material were removed reaching 120µm in depth.
Como referenciar
AMARAL, MARCELLO M.; RAELE, MARCUS P.; FREITAS, ANDERSON Z. de; ZAHN, GUILHERME S.; SAMAD, RICARDO E.; VIEIRA JUNIOR, NILSON D.; TARELHO, LUIZ V.G. Laser induced breakdown spectroscopy (LIBS) applied to stratigrafic elemental analysis and optical coherence tomography (OCT) to damage determination of cultural heritage brazilian coins. In: SPIE EUROPE: OPTICAL METROLOGY, 14-18 June, 2009, Munique, Alemanha. Proceedings... (SPIE Proceedings Series, 7390). Disponível em: http://repositorio.ipen.br/handle/123456789/16658. Acesso em: 30 Dec 2025.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.