Personne : Laroche, Gaétan
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Laroche
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Gaétan
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Université Laval. Département de génie des mines, de la métallurgie et des matériaux
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ncf10316941
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Publication Accès libre Fourier-Transform infrared spectroscopy of ethyl lactate decomposition and thin-film coating in a filamentary and a glow dielectric barrier discharge(Wiley-VCH-Verl., 2021-07-05) Milaniak, Natalia; Laroche, Gaétan; Massines, FrançoiseGlow and filamentary regimes of atmospheric pressure plasma-enhanced chemical vapor deposition in a planar dielectric barrier discharge configuration were compared for thin-film deposition from ethyl lactate (EL). EL decomposition in the plasma phase and thin-film composition were both characterized by Fourier- transform infrared spectroscopy. EL chemical bonds' concentration along the gas flow decreases progressively in the glow dielectric barrier discharge (GDBD), whereas it drastically oscillates in the filamentary dielectric barrier discharge (FDBD), with values higher than that of the initial mixture. EL decomposition route depends on the discharge regime, as the decrease of the concentration of the different investigated bonds is different for an identical amount of energy provided to EL molecules. CO2 is systematically formed reaching concentrations of 25 and 40 ppm, respectively, in FDBD and GDBD.Publication Restreint Atmospheric-pressure plasma-enhanced chemical vapor deposition of nanocomposite thin films from ethyl lactate and silica nanoparticles(Weinheim Wiley-VCH-Verl., 2020-10-09) Milaniak, Natalia; Laroche, Gaétan; Massines, FrançoiseNanocomposite coatings are made by atmospheric-pressure plasma-enhanced chemical vapor deposition from ethyl lactate (EL) and silica nanoparticles (NPs) in a dielectric barrier discharge (DBD) using frequency-shift keying (FSK) to alternate between 1- and 15-kHz voltages. In situ plasma Fourier-transform infrared spectroscopy (FTIR) and thin film FTIR, scanning electron microscopy, atomic force microscopy, and profilometry show that (i) 1 kHz DBD mainly deposits NPs, 15 kHz only polymerizes EL; (ii) the EL polymerization rate is the same in FSK and continuous modes; (iii) despite the 50/50 contribution of both frequencies, the NP deposit is three times faster in FSK mode than in 1 kHz DBD and compared with 1 and 15 kHz coatings, in the nanocomposite, NP Si–O–Si and EL C═O bonds per unit length are equal to 68% and 34%, respectively. In situ FTIR detects SiO2 NPs, their functionalization, and the formation of CO2.Publication Accès libre Interpretation of artifacts in Fourier transform infrared spectra of atmospheric pressure dielectric barrier discharges : relationship with the plasma frequency between 300 Hz and 15 kHz(Institute of physics, 2019-10-11) Milaniak, Natalia; Audet, Pierre; Laroche, Gaétan; Griffiths, Peter R.; Massines, FrançoiseThis article describes the occurrence of a phenomenon that is observed while recording mid-infrared (4000–700 cm−1) absorption spectra of dielectric barrier discharges sustained at frequencies ranging from 300 Hz to 15 kHz. This phenomenon is observed as the presence of very sharp spikes in the spectrum, for which the wavenumber depends on both the high voltage frequency used to generate the discharge and the velocity of the moving mirror of the interferometer (which in turn determines the interferogram sampling frequency). While it is well known that the consumption of gas precursor within plasmas can be followed, we demonstrate that Fourier transform infrared spectroscopy also makes it possible to monitor frequencies and coupling of excitation mechanisms occurring in the plasma.