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High Temperature Material Processes: An International Quarterly of High-Technology Plasma Processes

Impact factor: 0.058

ISSN Print: 1093-3611
ISSN Online: 1940-4360

High Temperature Material Processes: An International Quarterly of High-Technology Plasma Processes

DOI: 10.1615/HighTempMatProc.v4.i1.70
18 pages

TIME RESOLVED LASER INDUCED BREAKDOWN SPECTROSCOPY FOR FLUORINE, CHLORINE AND SULFUR DETECTION USING AN OPTICAL FIBER PROBE

H. Lancelin
Centre d'Etudes du Bouchet, Direction des Centres d'Expertise et d'Essais, BP 3,91710 Vert-le-Petit, FRANCE
L. Dudragne
Centre d'Etudes du Bouchet, Direction des Centres d'Expertise et d'Essais, BP 3,91710 Vert-le-Petit, FRANCE
P. Adam
Section détection physique, Centre d’Etudes du Bouchet, Direction des Centres d'Expertise et d'Essais, Delegation Generate pour l’Armement, BP 3, 91710 Vert le Petit, France
Jacques Amouroux
Laboratoire de Genie des Precedes Plasmas Universite P. et M. Curie, ENSCP 11 rue P. et M. Curie 75005 Paris France

ABSTRACT

Our goal is to develop an optical spectroscopy analysis of toxic molecular compounds by using the atomic emission of a plasma induced by a Nd:YAG laser (TRELIBS). The qualitative and quantitative analysis have been carried out on chlorine and fluorine atoms from organohalogenated molecules. The experimental setup uses a Nd:YAG laser at 1064 nm and a cylindrical cell in stainless steel through which the gas flow is introduced. The laser beam is focused in the cell through a BK7 lens, while the emission wavelengths are analyzed by a 24 optical fiber probe connected to a spectrometer with an optical multichannel analyzer, and a computer. The time resolution of plasma emissions with a gated image intensifier leads us to a best signal to noise ratio (SNR) on atomic emission lines with 0.5 to 4 μs delay between the end of the laser pulse and the detector aperture. Spectral, time and space resolution permit a high reproducibility and a good sensitivity of the method (close to 10 ppm(w/w)).
The high temperature of the plasma produced by a laser beam of 100 mJ is responsible of the total decomposition of the molecular structure and explains the high excitation states of the atoms such as Cl, F, S, P.