Tubular electrode torch for capacitatively coupled helium microwave plasma as a spectrochemical excitation source

Patel, Bhavana; Heithmar, Edward M.; Winefordner, J. D.

doi:10.1021/ac00146a012

Cited by 44 publications

(8 citation statements)

References 31 publications

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“…Figure shows the emission spectrum of the atmospheric pressure helium plasma for the wavelength region between 240 and 500 nm. The spectrum shows typical helium emission lines and significant molecular bands of OH, NH, N 2 , and N 2 + species − due to the presence of impurities such as water, N 2 , O 2 , and hydrocarbons. The C(I) atomic line at 247.86 nm, ,, which is commonly observed in other plasmas such as microwave-induced plasma, is absent.…”

Section: Resultsmentioning

confidence: 99%

“…The spectrum shows typical helium emission lines and significant molecular bands of OH, NH, N 2 , and N 2 + species − due to the presence of impurities such as water, N 2 , O 2 , and hydrocarbons. The C(I) atomic line at 247.86 nm, ,, which is commonly observed in other plasmas such as microwave-induced plasma, is absent. This result may be due to several factors, such as high purity of helium, low discharge power, and short residence time (6.9 ms at a plasma gas flow rate of 1 L/min).…”

Section: Resultsmentioning

confidence: 99%

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A Low-Power, Atmospheric Pressure, Pulsed Plasma Source for Molecular Emission Spectrometry

Jin

Duan

2000

Anal. Chem.

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A low-power, plasma source-based, portable molecular emission detector is described in this paper. The detector employs a pulsed-plasma source operated at atmospheric pressure for molecular fragmentation and excitation. The plasma was generated with a home-built high-voltage pulsed power supply. The average operational power of the detector was less than 0.2 W. The effects of operational parameters such as plasma gas, voltage, and plasma gas flow rate were investigated. Molecular emission spectra of a variety of organic compounds were studied. The features of the emission spectra obtained with the pulsed plasma source were significantly different from those obtained with direct current (dc) discharge at a power higher than 10 W. The spectra obtained in this work showed strong CH emission at 431.2 nm; however, the typical CN emission observed with a conventional dc plasma source at 383-388 nm was very weak in most cases. The strong CN emission was only obtained for compounds containing nitrogen, such as aniline. Dimethyl sulfoxide can be detected at a limit of 200 ppb using helium plasma by observing the emission band of the CH radical. The detector was very stable and did not experience electrode fouling even with the introduction of organic vapors. Such a detector is very promising for organic vapor detection.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

A Low-Power, Atmospheric Pressure, Pulsed Plasma Source for Molecular Emission Spectrometry

Jin

Duan

2000

Anal. Chem.

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“…were gathered in the wavelengths between 690–925 nm by the transition of 4p → 4s. The strong emission lines of OH (A 2 Σ → X 2 Π) at 308.81 nm, NH (A 3 Π → X 3 Σ − ) at 335.79 nm, and N 2 (C 3 Π μ → B 3 Π g ) at 356.66 nm and 379.81 nm were also found in the region of 280–380 nm due to the presence of impurities such as water and nitrogen in argon and back-diffusion air2728. The formation of excited N 2 and OH may attribute to the Penning ionization (Ar* + N 2 0 → N 2 (C 3 Π μ ) + Ar 0 ; N 2 (C 3 Π μ ) → N 2 (B 3 Π g ) + hv; Ar* + H 2 O → OH + H + Ar 0 ) and energy transfer (N 2 0 + e − → N 2 * + e − ; H 2 O + e − → OH + H + e − ).…”

Section: Resultsmentioning

confidence: 99%

Chip-based ingroove microplasma with orthogonal signal collection: new approach for carbon-containing species detection through open air reaction for performance enhancement

Meng

Duan

2014

Sci Rep

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A novel microplasma generator based on ceramic chips has been developed and coupled with optical emission spectrometry through orthogonal detection. Stable microplasma was generated between two electrodes in the ingroove discharge chamber and the optical fiber was set in perpendicular to the gas outlet to collect emitted light. The emission signal of CN is surprisingly enhanced by reacting carbon-containing species with back-diffusion nitrogen from open air, and the enhanced CN signal is successfully applied to sensitively detect organic compounds for the first time. This article focuses to study the structural characteristic and the signal enhancement mechanism through back-diffusion reaction. Several organic compounds were detected directly with the limits of detection down to ppb level. Besides, the advantages of low energy consumption and the chip-based discharge chamber show great potential to be applied in portable devices. This development may lead to a new way for the sensitive detection of organic compounds.

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“…As mentioned above, the capacitive mode of coupling exists when the plasma has at least one point of immediate contact with electric conductor. Plasma can be operated at the tip of the metal electrode sustained with Ar, He and even with air, N 2 or H 2 at a MW power ranging from 10 to 2000 W. [38][39][40] The tip material (W, Mo, Ta, brass 38,[41][42][43] ) does not have to take part in plasma formation avoiding extensive degradation or evaporation. Despite plasma-metallic electrode contact, there is no contamination in the spectrum.…”

Section: Nature Of Microwave Coupling: Cmp and Mipmentioning

confidence: 99%

Recent developments in instrumentation of microwave plasma sources for optical emission and mass spectrometry: Tutorial review

Jankowski

Reszke²

2013

J. Anal. At. Spectrom.

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This paper reviews the most common methods of generation of plasmas using microwaves with special emphasis on recently developed microwave plasma (MWP) sources for analytical applications. The art and science of microwave plasma optical and mass spectroscopy instrumentation (MWP-OES/MS), and the applications are briefly presented, including very recent advances in the field as of 2012. The design and operation of MWPs is discussed to provide a basic understanding of the most important selection criteria when designing MWP systems. The various plasma generation systems described include single-electrode capacitive microwave plasmas, electrodeless inductively coupled plasmas, multi-electrode systems energized with stationary or rotating fields. We also discuss various technical realizations of MWP sources for selected applications. Examples of technical realizations of plasmas in closed structures (cavities), in open structures (surfatrons, planar plasma sources), and in magnetic fields (Hammer cavity) are discussed in detail. Finally, we mention micro-and mini-discharges as convenient sources for miniaturized spectrometric systems. Specific topics include fundamental aspects of MWP, i.e., recent advances in the construction of analytical MWPs (coaxially coupled cavities, strip-line technology, multi-point energizing, power combining, rotating fieldexcited plasmas), operational characteristics, analytical characteristics and applications. Special reference is made to coupling with OES for determination of chromatographic effluents and particle sizing. The developments in elemental and molecular MS applications in both low-power and high-power MWPs are also discussed.

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Tubular electrode torch for capacitatively coupled helium microwave plasma as a spectrochemical excitation source

Cited by 44 publications

References 31 publications

A Low-Power, Atmospheric Pressure, Pulsed Plasma Source for Molecular Emission Spectrometry

A Low-Power, Atmospheric Pressure, Pulsed Plasma Source for Molecular Emission Spectrometry

Chip-based ingroove microplasma with orthogonal signal collection: new approach for carbon-containing species detection through open air reaction for performance enhancement

Recent developments in instrumentation of microwave plasma sources for optical emission and mass spectrometry: Tutorial review

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