Characterization of an inductively coupled N<sub>2</sub>plasma using sensitive diode laser spectroscopy

Bakowski, B.; Hancock, Gus; Peverall, R.; Ritchie, Grant A. D.; Thornton, Lee

doi:10.1088/0022-3727/37/15/004

Cited by 29 publications

(35 citation statements)

References 40 publications

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“…Translational and rotational temperatures of electronically excited N 2 A 3 S þ u molecules, formed in an inductively coupled nitrogen plasma, were measured by Bakowski et al 179 using CEAS via the B 3 P g (v 5 3)-A 3 S þ u (v 5 0) band at 686 nm. The two temperatures were found to be in equilibrium, but varied from 300 to 450 K at respective applied powers of 5 and 400 W. Absolute number densities of N 2 (A) were also determined, with the v 5 0 population measured to be 1.19 ¡ 0.07 6 10 10 cm 23 at 100 W and 10 mTorr total pressure.…”

Section: Plasma and Flame Chemistry Diagnosticsmentioning

confidence: 99%

4 Cavity ring-down and cavity enhanced spectroscopy using diode lasers

Mazurenka

Orr-Ewing

Peverall

et al. 2005

Annu. Rep. Prog. Chem., Sect. C

243

174

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Continuous wave (cw) diode lasers are increasingly being used as light sources in the visible and near-IR regions of the spectrum for cavity ringdown spectroscopy (CRDS) and cavity enhanced absorption spectroscopy (CEAS); the latter technique is also widely known as integrated cavity output spectroscopy (ICOS). The very high sensitivities to weak absorptions that are possible with cw CRDS and CEAS, coupled with the quantitative nature of the absorption measurements, are enabling a rapidly expanding range of applications. We review the benefits and practical implementation of these techniques; methods of data analysis for extraction of quantitative absorption data; the sensitivities of cw CRDS and CEAS, and how they might be optimised; and applications of cw CRDS and CEAS in molecular spectroscopy, atmospheric chemistry, plasma and flame chemistry, analytical science, and medical diagnosis via breath analysis. The development of CRDS and CEAS techniques exploiting cw diode lasers and, very recently, high luminosity light-emitting diodes, has stimulated a wealth of highsensitivity measurements. Highlights include quantitative measurement of various ultra-trace gases such as: NO 3 , NO 2 and ethene in ambient air samples; CO 2 isotopologues, ethane and other organic compounds in human breath samples; and excited electronic states of N 2 and O 2 in plasmas and discharges. Exciting developments include wavelength extension into the mid-IR and UV regions, and use of novel locked-cavity techniques to increase data acquisition rates and sensitivities.

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Section: Plasma and Flame Chemistry Diagnosticsmentioning

confidence: 99%

4 Cavity ring-down and cavity enhanced spectroscopy using diode lasers

Mazurenka

Orr-Ewing

Peverall

et al. 2005

Annu. Rep. Prog. Chem., Sect. C

243

174

View full text Add to dashboard Cite

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“…The experimental arrangement and the plasma chamber used in this study have been described in detail elsewhere [21] and so only a brief description is given here. The ICP chamber is of cylindrical geometry (height × width = 21 × 35 cm) and is powered through a quartz dielectric interface (diameter = 25 cm) via a coil-type rf electrode.…”

Section: Introductionmentioning

confidence: 99%

Quantitative measurements of singlet molecular oxygen in a low pressure ICP

Rogers

Bond

Peverall

et al. 2021

Plasma Sources Sci. Technol.

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We present measurements of the densities and temperatures (rotational and translational) of the metastable a 1 Δ g (v = 0) state of O 2 in a cylindrically symmetric RF driven plasma operating in inductive mode at 100 mTorr total pressure and 300 W applied power. Line-of-sight absorption across the plasma region was determined by diode laser cavity ringdown spectroscopy on the (0, 0) vibrational band of the O 2 (b 1 Σ g + ) ← O 2 (a 1 Δ g ) transition near 1.9 μm. Four rotational quantum states were studied, with a population distribution corresponding to a rotational temperature of 346 ± 38 K. The translational temperature was determined to be 359 ± 16 K from the width of the strongest absorption line, Q(12), and in equilibrium with the rotational distribution. The absolute concentration of O 2 (a 1 Δ g , v = 0) was measured as (9.5 ± 1.3) × 10 13 cm −3 , and corresponds to an apparent (3.5 ± 0.45)% contribution to the total number density. Time-resolved CRDS measurements following plasma extinction were used to deduce a wall loss coefficient, γ, of (2.8 ± 0.3) × 10 −3 on predominantly Al surfaces. Surmising reasonable concentrations for O 2 (b 1 Σ g + ) and an upper limit for the vibrational temperature places the total contribution of O 2 (a 1 Δ g ) at between 3.6% and 5.85%. The variation of the O 2 (a 1 Δ g , v = 0) state concentration with RF power shows a clear transition from the E to H mode excitation near an applied power of 150 W. Allan variance analysis yields a minimum measurable concentration of O 2 (a 1 Δ g , v = 0) of 1.1 × 10 12 cm −3 over 100 ringdown events, an order of magnitude more sensitive than previously reported.

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“…Absolute measures of N 2 * and atomic N density in plasmas have been measured using laser-induced fluorescence [27,28], threshold ionization mass spectrometry [29], and absorption spectroscopy [30]. Unfortunately these advanced techniques require dedicated equipment that typically is not compatible with deposition systems.…”

Section: N 2 Optical Emission Spectramentioning

confidence: 99%