Absorption spectroscopy measurements of resonant and metastable atom densities in atmospheric-pressure discharges using a low-pressure lamp as a spectral-line source and comparison with a collisional-radiative model

Castaños-Martínez, Eduardo; Moisan, M.

doi:10.1016/j.sab.2009.12.003

Cited by 31 publications

(13 citation statements)

References 40 publications

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“…where I p+l is the emission of the plasma with the lamp on, I p is the emission of the plasma with the lamp off, and I l is the emission of the lamp with the plasma off. The analysis method was then adopted from Castaños-Martinez and Moisan [28] to take into account the difference in pressure broadening between the low-pressure Ar lamp and the atmospheric-pressure Ar plasma. This method assumed a Voigt line profile to carry out the analysis, thus taking into account the pressure broadening of the Ar emission lines from the plasma.…”

Section: Optical Absorption Spectroscopymentioning

confidence: 99%

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Spatially-Resolved Spectroscopic Diagnostics of a Miniature RF Atmospheric Pressure Plasma Jet in Argon Open to Ambient Air

Sainct

Durocher‐Jean

Gangwar

et al. 2020

Plasma

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The spatially-resolved electron temperature, rotational temperature, and number density of the two metastable Ar 1 s levels were investigated in a miniature RF Ar glow discharge jet at atmospheric pressure. The 1 s level population densities were determined from optical absorption spectroscopy (OAS) measurements assuming a Voigt profile for the plasma emission and a Gaussian profile for the lamp emission. As for the electron temperature, it was deduced from the comparison of the measured Ar 2 p i → 1 s j emission lines with those simulated using a collisional-radiative model. The Ar 1 s level population higher than 10 18 m − 3 and electron temperature around 2.5 eV were obtained close to the nozzle exit. In addition, both values decreased steadily along the discharge axis. Rotational temperatures determined from OH(A) and N 2 (C) optical emission featured a large difference with the gas temperature found from a thermocouple; a feature ascribed to the population of emitting OH and N 2 states by energy transfer reactions involving the Ar 1 s levels.

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Section: Optical Absorption Spectroscopymentioning

confidence: 99%

“…This method assumed a Voigt line profile to carry out the analysis, thus taking into account the pressure broadening of the Ar emission lines from the plasma. As a result, the frequency-integrated absorption coefficient for each individual line can be expressed as [28]:…”

Section: Optical Absorption Spectroscopymentioning

confidence: 99%

Spatially-Resolved Spectroscopic Diagnostics of a Miniature RF Atmospheric Pressure Plasma Jet in Argon Open to Ambient Air

Sainct

Durocher‐Jean

Gangwar

et al. 2020

Plasma

View full text Add to dashboard Cite

show abstract

“…However, because of radiation trapping, the actual lifetime is much longer, such that ray ¼ g 0 , where g is the trapping coefficient. 43 Here we have considered that trapping occurs both in the radial (g \ ) and in the longitudinal (g k ) directions, such that we use the heuristic trapping coefficient…”

Section: Particle Balance With Excited Statesmentioning

confidence: 99%

A global model of the self-pulsing regime of micro-hollow cathode discharges

Lazzaroni

Chabert

2012

Journal of Applied Physics

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International audienceA global (volume-averaged) model of the self-pulsing regime of micro-hollow cathode discharges working in argon gas is proposed. The power balance is done using an equivalent circuit model of the discharge that allows the current and voltage dynamics to be calculated. The fraction of the total power dissipated in the discharge that contributes to electron heating is deduced from a sheath model previously described. The particle balance is first done in a very simplified reaction scheme involving only electrons, argon atomic ions, and argon molecular ions. In a second step, the excited states (the metastable state Ar*(3P2) and the resonant state Ar*(3P1)) are included in the particle balance equations. The models are compared to experiments and several conclusions are drawn. The model without excited states underestimates the electron density and does not capture well the trends in pressure. The model with the excited states is in better agreement which shows that multi-step ionization plays a significant role. The time-evolution of the electron density follows closely that of the discharge current but the excited states density presents two peaks: (i) the first at the early stage of the current peak due to direct excitation with high electron temperature, (ii) the second at the end of the current (and electron density) peak due to large production of excited states by electron-ion recombination at very low electron temperature

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“…Using the approach proposed by Michell and Zemansky 23 for Doppler-broadened lines, the absorption coefficient at the center of the line, k 0 0 can be calculated assuming that the lines emitted from lamp and plasma have Gaussian profile (see Ref. 24)…”

Section: Experimental Setup and Diagnosticsmentioning

confidence: 99%

Determination of the number density of excited and ground Zn atoms during rf magnetron sputtering of ZnO target

Maaloul

Gangwar

Stafford

2015

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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A combination of optical absorption spectroscopy (OAS) and optical emission spectroscopy measurements was used to monitor the number density of Zn atoms in excited 4s4p (3P2 and 3P0) metastable states as well as in ground 4s2 (1S0) state in a 5 mTorr Ar radio-frequency (RF) magnetron sputtering plasma used for the deposition of ZnO-based thin films. OAS measurements revealed an increase by about one order of magnitude of Zn 3P2 and 3P0 metastable atoms by varying the self-bias voltage on the ZnO target from −115 to −300 V. Over the whole range of experimental conditions investigated, the triplet-to-singlet metastable density ratio was 5 ± 1, which matches the statistical weight ratio of these states in Boltzmann equilibrium. Construction of a Boltzmann plot using all Zn I emission lines in the 200–500 nm revealed a constant excitation temperature of 0.33 ± 0.04 eV. In combination with measured populations of Zn 3P2 and 3P0 metastable atoms, this temperature was used to extrapolate the absolute number density of ground state Zn atoms. The results were found to be in excellent agreement with those obtained previously by actinometry on Zn atoms using Ar as the actinometer gas [L. Maaloul and L. Stafford, J. Vac. Sci. Technol., A 31, 061306 (2013)]. This set of data was then correlated to spectroscopic ellipsometry measurements of the deposition rate of Zn atoms on a Si substrate positioned at 12 cm away from the ZnO target. The deposition rate scaled linearly with the number density of Zn atoms. In sharp contrast with previous studies on RF magnetron sputtering of Cu targets, these findings indicate that metastable atoms play a negligible role on the plasma deposition dynamics of Zn-based coatings.

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Absorption spectroscopy measurements of resonant and metastable atom densities in atmospheric-pressure discharges using a low-pressure lamp as a spectral-line source and comparison with a collisional-radiative model

Cited by 31 publications

References 40 publications

Spatially-Resolved Spectroscopic Diagnostics of a Miniature RF Atmospheric Pressure Plasma Jet in Argon Open to Ambient Air

Spatially-Resolved Spectroscopic Diagnostics of a Miniature RF Atmospheric Pressure Plasma Jet in Argon Open to Ambient Air

A global model of the self-pulsing regime of micro-hollow cathode discharges

Determination of the number density of excited and ground Zn atoms during rf magnetron sputtering of ZnO target

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