Investigation of a pulsed oxygen microwave plasma by time-resolved two-photon allowed laser-induced fluorescence

Georg, Andreas; Engemann, J.; Brockhaus, A.

doi:10.1088/0022-3727/35/9/307

Cited by 33 publications

(22 citation statements)

References 17 publications

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“…The initiation step of APTES decomposition is attributed to atomic oxygen. To the best of our knowledge, contrary to O atoms [52][53][54][55], the singlet state O 2 (a 1 ∆ g ) has never been identified as a reactive species with regards to dehydrogenation of organosilicon compounds. Afterglow studies with TEOS [52][53][54] and HMDSO [48,53] all reinforce this conclusion.…”

Section: Mechanisms At Stakementioning

confidence: 95%

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Interaction of (3-Aminopropyl)triethoxysilane with Pulsed Ar–O2 Afterglow: Application to Nanoparticles Synthesis

Gueye

Gries

Noël

et al. 2016

Plasma Chem Plasma Process

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The interaction of (3-Aminopropyl)triethoxysilane (APTES) with pulsed late Ar-O 2 afterglow is characterized by the synthesis of OH, CO and CO 2 in the gas phase as main by-products. Other minor species like CH, CN and C 2 H are also produced. We suggest that OH radicals are produced in a first step by dehydrogenation of APTES after interaction with oxygen atoms. In a second step, the molecule is oxidized by any O 2 state, to form peroxides that transform into by-products, break thus the precursor CC bonds. If oxidation is limited, i.e. a low duty cycle, fragmentation of the precursor is limited and produced nanoparticles keep the backbone structure of the precursor, but contain amide groups produced from the amine groups initially available in APTES. At high duty cycle, silicon-containing fragments contain some carbon and react together and produce nanoparticles with a non-silica-like structure.

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Section: Mechanisms At Stakementioning

confidence: 95%

“…Finally, Georg et al [55] proposed that a major reason for thin films improvement of roughness and homogeneity is the enhanced oxidation of unwanted carbohydrogen compounds in the HMDSO molecules by atomic oxygen.…”

Section: Mechanisms At Stakementioning

confidence: 99%

Interaction of (3-Aminopropyl)triethoxysilane with Pulsed Ar–O2 Afterglow: Application to Nanoparticles Synthesis

Gueye

Gries

Noël

et al. 2016

Plasma Chem Plasma Process

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“…There are three likely processes to produce atomic oxygen; one is to dissociate an oxygen molecule into two oxygen atoms via the reaction e + O 2  2O + e, which has a reaction rate coefficient k 1 = 4.2  10 -9 exp(-5.6/T e ) [37], where T e is in eV. This reaction rate decreases rapidly with T e < 5.6 eV; thus it needs about 5 eV electrons to effectively dissociate O 2 into atomic oxygen.…”

Section: Design Of the Devicementioning

confidence: 99%

Air plasma for medical applications

Kuo

2012

JBiSE

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The design and the electric and emission characteristics of two handheld air plasma spray generators are presented. The plasma is generated by 60 Hz periodic discharges between two concentrically cylindrical electrodes. A ring magnet is used to rotate arc discharges, which sprays outward by an air flow. The rotation of arc discharges keeps the generated plasma in non-equilibrium state and at relatively low temperature (<55°C). The plasma effluent yet contains high energy electrons which dissociate molecular oxygen into atomic oxygen. The emission spectroscopy of the plasma plume reveals that the plasma effluent, which carries abundant atomic oxygen, extends from the cap of the plasma spray by about 25 to 30 mm. Tests on blood droplets and smeared blood samples revealed the effectiveness and mechanism of low temperature air plasma on clotting blood. Tests on oral pathogens show that air plasma creates a zone of microbial growth inhibition in each of six treated samples, including those of grampositive bacteria and fungi, and on a cultivating biofilm sample of Streptococcus mutans UA159. The medical applications of the air plasma sprays for 1) bleeding control, 2) wound healing, and 3) dental disinfection, are then illustrated and discussed. As animal models, pigs were used in the tests of stopping wound bleeding and post-operative observation of wound healing by this air plasma spray. The results show that the bleeding from a cut to an ear artery is stopped swiftly; this air plasma spray also shortens wound healing time to about half (from 14 days to 8 days) after stopping the bleeding of a cross cut wound in the ham area. In-vitro tests demonstrate that the plasma effluent of the spray can prevent the formation of dental biofilms and further eliminate the mature biofilms

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“…The measured transmission of the interferential filters are respectively T Xe = 38% and T O = 81%. According to the literature [1], the optical branching ratio for the atomic oxygen transition 3p 3 P J → 3s 3 S is equal to unity (a 0 (O) = 1) and a 0 (Xe) = 0.733 for xenon transition 6p'[3/2] 2 → 6s'[1/2] 1 while the ratio of the two-photon excitation cross sections is σ (2) Xe /σ…”

Section: Introductionmentioning

confidence: 99%

Quantitative Determination of Density of Ground State Atomic Oxygen from Both TALIF and Emission Spectroscopy in Hot Air Plasma Generated by Microwave Resonant Cavity

Marchal

Yousfi

Merbahi

et al. 2016

Plasma Sci. Technol.

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Two experimental techniques have been used to quantify the atomic oxygen density in the case of hot air plasma generated by a microwave (MW) resonant cavity. The latter operates at a frequency of 2.45 GHz inside a cell of gas conditioning at a pressure of 600 mbar, an injected air flow of 12 L/min and an input MW power of 1 kW. The first technique is based on the standard two photon absorption laser induced fluorescence (TALIF) using xenon for calibration but applied for the first time in the present post discharge hot air plasma column having a temperature of about 4500 K near the axis of the nozzle. The second diagnostic technique is an actinometry method based on optical emission spectroscopy (OES). In this case, we compared the spectra intensities of a specific atomic oxygen line (844 nm) and the closest wavelength xenon line (823 nm). The two lines need to be collected under absolutely the same spectroscopic parameters. The xenon emission is due to the addition of a small proportion of xenon (1% Xe) of this chemically inert gas inside the air while a further small quantity of H2 (2%) is also added in the mixture in order to collect OH(A-X) and NH(A-X) spectra without noise. The latter molecular spectra are required to estimate gas and excitation temperatures. Optical emission spectroscopy measurements, at for instance the position z=12 mm on the axis plasma column that leads to a gas measured temperature equal to 3500 K, an excitation temperature of about 9500 K and an atomic oxygen density 2.09×10 17 ± 0.2×10 17 cm −3. This is in very good agreement with the TALIF measurement, which is equal to 2.0×10 17 cm −3 .

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Investigation of a pulsed oxygen microwave plasma by time-resolved two-photon allowed laser-induced fluorescence

Cited by 33 publications

References 17 publications

Interaction of (3-Aminopropyl)triethoxysilane with Pulsed Ar–O2 Afterglow: Application to Nanoparticles Synthesis

Interaction of (3-Aminopropyl)triethoxysilane with Pulsed Ar–O2 Afterglow: Application to Nanoparticles Synthesis

Air plasma for medical applications

Quantitative Determination of Density of Ground State Atomic Oxygen from Both TALIF and Emission Spectroscopy in Hot Air Plasma Generated by Microwave Resonant Cavity

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