Spectral, spatial and temporal characteristics of a millisecond pulsed glow discharge: metastable argon atom production

Jackson, Glen P.; Lewis, C.L.; Doorn, Stephen K.; Majidi, Vahid; King, Fred L.

doi:10.1016/s0584-8547(01)00329-9

Cited by 61 publications

(72 citation statements)

References 42 publications

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“…This hypothesis has been confirmed by an optical investigation performed in this lab, in which charge transfer processes were found to maximize at ϳ5 mm and decrease sharply with increasing distance [32]. Penning ionization, however, exhibits a different spatial profile because the metastable argon atom density is distributed more evenly throughout the negative glow region [11]. For this reason, Penning ionization is expected to exhibit a more moderate decrease with increasing distance.…”

Section: Spatial Characteristics Of P()mentioning

confidence: 62%

“…As a direct consequence of the recombination the Ar ϩ population, as evidenced by the ion intensity (Figure 5), suffered a sharp decrease upon the power termination, eliminating charge transfer from being a major ionization mechanism in the afterpeak regime. Meanwhile, the recombination of argon ions and electrons followed by radiative decay produces a large population of metastable argon atoms, which in turn greatly enhances Penning ionization [11,12] to the point that it becomes the dominant ionization process in the afterpeak regime [27].…”

Section: Temporal Characteristics Of P() Over a Pulse Cyclementioning

confidence: 99%

“…The population of each energetic species and the corresponding ionization process vary with location in the plasma [11,12]. Analyte molecules at each location are subject to a specific convolution of energy transfer processes, resulting in a unique P().…”

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confidence: 99%

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Millisecond pulsed radio frequency glow discharge time of flight mass spectrometry: Temporal and spatial variations in molecular energetics

Millay

Turner

et al. 2004

J. Am. Soc. Mass Spectrom.

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The internal energy distributions, P(epsilon), of a millisecond pulsed radio frequency glow discharge plasma were investigated using tungsten hexcarbonyl W(CO)(6) as a "thermometer molecule". Vapor of the probe molecule, W(CO)(6), was introduced into the plasma and subjected to various ionization and excitation processes therein. The resultant molecular and fragment ions were monitored using a Time-of-Flight mass spectrometer. Ion abundance data were utilized in combination with the known energetics of W(CO)(6) to construct the P(epsilon) plots. The P(epsilon) of W(CO)(6) exhibited strong temporal dependence over the pulse cycle: Distinct internal energy distributions were found at the discharge breakdown period (prepeak), the steady state period (plateau), and the post-pulse period (afterpeak). Spatial variation in P(epsilon) was also observed, especially during the plateau regime. The observations suggest that this pulsed glow discharge affords excellent energy tunability that can be used to perform selective ionization and fragmentation for molecular, structural, and elemental information. Parametric studies were performed to evaluate the effects of discharge pressure and operating power on P(epsilon). These studies also provided insight into the correlation of the observed P(epsilon)s with the fundamental ionization and excitation mechanisms in the plasma. The temporal and spatial variations in P(epsilon) were hence attributed to changes in the dominant energy transfer processes at specific times in specific regions of the plasma. These data will be useful in future efforts to optimize the analytical performance of this source for chemical speciation.

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Section: Spatial Characteristics Of P()mentioning

confidence: 62%

Section: Temporal Characteristics Of P() Over a Pulse Cyclementioning

confidence: 99%

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Millisecond pulsed radio frequency glow discharge time of flight mass spectrometry: Temporal and spatial variations in molecular energetics

Millay

Turner

et al. 2004

J. Am. Soc. Mass Spectrom.

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“…By using a pulsed GD, it is possible to achieve a high instantaneous pulse power, avoiding over heating of the cathode [12][13][14] and generating different temporal regimes [15,16]. These regimes, prepeak, plateau, and afterglow, provide different information about the composition of a sample [17].…”

Section: Introductionmentioning

confidence: 99%

Tunable fragmentation of organic molecules in laser ablation glow discharge time-of-flight mass spectrometry

Lotito¹,

Günther²

2011

Anal Bioanal Chem

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A DC-pulsed glow discharge (GD) has distinct temporal regimes which are characterized by "softer" or "harder" ionization of analytes introduced into the discharge. It is thus possible to obtain both molecular weight and structural fragment information from the same spectra. In order to extend the capabilities of this technique a laser ablation (LA) sampling system was coupled to a DC-pulsed GD and to a time-of-flight (TOF) mass spectrometer (MS) for characterizing organic samples such as oleic acid, reserpine, two different peptides, and a polymer. Both hard and soft ionization regimes were studied. These LAGD-TOFMS results were compared to matrix-assisted laser desorption ionization (MALDI) spectra using the same compounds (i.e., analytes, concentration, and matrix). It was found that LAGD offers tunable ionization and provides a reduced matrix dependence. However, the sensitivity achieved by the prototype LAGD-TOFMS was significantly lower when compared with commercially available MALDI-TOFMS instrumentation. Since LAGD-TOFMS is rather new, some technical details to increase its sensitivity are discussed.

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“…Studies have been conducted to examine the temporal and spatial emission characteristics occurring in pulsed glow discharges and the possibility of temporal separation of different ionisation and excitation processes over the pulse cycle (for example electron and Penning ionisation) has been demonstrated. King and co-workers [70,71] observed no pre-peak in pulsed millisecond dc profiles of copper atom transitions, whereas each transition resulted in an after-peak. Previous emission reports from a pulsed rf-GD [68] showed a series of anomalies (presence of prepeaks and absence of after-peaks) in some copper emission transitions, not previously observed using the dc-GD counterpart.…”

Section: Pulsed Rf-gdmentioning

confidence: 99%

Radiofrequency glow-discharge devices for direct solid analysis

Pisonero

Costa

Pereiro

et al. 2004

Analytical and Bioanalytical Chemistry

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The enormous potential of radiofrequency glow discharges (rf-GD) as photon, atom, or ion sources, coupled to spectrometric techniques, for rapid direct analysis of almost any conductor, semiconductor, or insulating material with good in-depth resolution has been demonstrated world-wide. This outstanding performance has prompted a great effort to develop and characterise rf-GD for direct materials analysis in recent years. The state of the art of rf-GD coupled to atomic absorption spectrometry, optical emission spectrometry, and mass spectrometry for direct solid analysis is reviewed here. A description of the principles of operation of the rf-GD and attempts to model these discharges are also given. Rf-GD instrumentation, both developed at research laboratories and commercially available, is described. Several practical examples are given demonstrating the capabilities of these techniques for bulk and depth-profile analysis. Finally, the research gaps to be filled for full implementation of rf-GD spectrometric techniques in industry and research centres alike for materials science studies and technical development are discussed.

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Spectral, spatial and temporal characteristics of a millisecond pulsed glow discharge: metastable argon atom production

Cited by 61 publications

References 42 publications

Millisecond pulsed radio frequency glow discharge time of flight mass spectrometry: Temporal and spatial variations in molecular energetics

Millisecond pulsed radio frequency glow discharge time of flight mass spectrometry: Temporal and spatial variations in molecular energetics

Tunable fragmentation of organic molecules in laser ablation glow discharge time-of-flight mass spectrometry

Radiofrequency glow-discharge devices for direct solid analysis

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