Fundamental Studies in the ICP Using a Sinusoidally Modulated Power Input

Parisi, Adriano; Hieftje, Gary M.

doi:10.1366/0003702864509556

Cited by 17 publications

(3 citation statements)

References 14 publications

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“…Later experiments on arcs were carried out by Kafrouni et al in 1979 [7]. Power modulations on ICPs were reported by Parisi and Hieftje [8] and by Olisek and Bradley [9]. They modulated the plasma power with a sinusoidal or a quasirectangular wave.…”

Section: Different Effects Of Power Interruptionsmentioning

confidence: 98%

“…The method that has been used is based on the study of the time-dependent behaviour of atomic line or molecular band intensities during short interruptions in the power generated by the microwave power supply. These measurements will be referred to as so-called 'power interruption (PI) experiments' [6][7][8][9][10][11][12][13]. Apart from insight into excitation balances, the PI experiments can reveal important aspects of transport phenomena, such as diffusion processes, heat conduction and convection.…”

Section: Introductionmentioning

confidence: 99%

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Excitation balances and transport properties in atmospheric microwave-induced plasmas studied by power interruption experiments

Timmermans¹,

Mullen

Thomas

et al. 2000

Plasma Sources Sci. Technol.

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Atmospheric microwave-induced argon plasmas with and without analyte injection have been exposed to power interruption experiments in order to study transport processes and to reveal dominant excitation balances. From the time-dependent behaviour of line intensities due to electron cooling and quenching during the power interruption, it is found that electron loss channels, such as diffusion, convection and the dissociative recombination of molecular ions, are much larger than for inductively coupled plasmas. It is found that in the ionizing part of the plasma electron dominated mechanisms are responsible for the population of radiative levels. Significant changes in the responses to power interruption are observed when small amounts of molecular compounds are injected (>0.5%), probably due to a decrease of the electron density. Furthermore, it is found that in the recombination zone downstream in the plasma an electron-independent excitation mechanism, probably thermal excitation, is responsible for the population of radiative levels of analytes with relatively low excitation energies. From the downstream propagation of a disturbance created in the ionizing part of the plasma the local axial gas velocity has been determined. In the analyte excitation zone of the plasma typical velocities are around 25 m s −1 , whereas in the recombining zone velocities of 12-18 m s −1 are obtained.

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Section: Different Effects Of Power Interruptionsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Excitation balances and transport properties in atmospheric microwave-induced plasmas studied by power interruption experiments

Timmermans¹,

Mullen

Thomas

et al. 2000

Plasma Sources Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…15 Modulated plasmas, however, have been used extensively to study plasma dynamics. 16,17,18 Potential bene® ts of a m odulated MIP include being able to use higher peak power, which could raise the attainable analyte emission levels, yet low average power, to extend the lifetime of the quartz discharge tube. In contrast to earlier investigations, the study perform ed here has as its principal goal to reduce the contribution of ICP emission to the TS background, and thereby to improve detection limits.…”

Section: Resultsmentioning

confidence: 99%

Inductively Coupled Plasma/Microwave-Induced Plasma Tandem Source for Atomic Emission Spectroscopy

Pack

Hieftje

2000

Appl Spectrosc

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A microwave-induced plasma (MIP)/inductively coupled plasma (ICP) combination has been evaluated as an “atomization-excitation” tandem source (TS). The results indicate that some of the problems reported for similar sources in the past can be effectively reduced or eliminated. Desolvation of the analyte aerosol before its introduction into the tandem source improved detection limits only slightly. However, power modulation of the microwave plasma served to improve tandem-source performance in two ways. First, noise contributed by the ICP and the MIP was isolated one from the other. Since the modulation frequency was chosen to be far removed from the major noise frequencies observed from either of the two sources, more stable background signals were realized. Second, the intense background signal from the ICP could be discriminated against through use of a lock-in-amplifier tuned to the modulated MIP signal. Relative standard deviations of both the signal and the background were usually below 1% when the MIP power was modulated. Detection limits ranged from 0.53 ppb to 40 ppb for the elements examined, which represents an improvement of 5-to 40-fold over previously reported data for a similar tandem-source configuration. Disappointingly, these improved detection limits were still much worse than detection limits obtained by other investigators utilizing the ICP alone. Addition of a mixed gas did little to improve the performance of the tandem source; for barium and calcium ion lines, an increase of approximately three in signal-to-background ratios was observed upon the addition of hydrogen or helium.

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Fundamental Principles of Inductively Coupled Plasmas

Mermet¹

2006

Inductively Coupled Plasma Spectrometry and Its Applications

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Fundamental Studies in the ICP Using a Sinusoidally Modulated Power Input

Cited by 17 publications

References 14 publications

Excitation balances and transport properties in atmospheric microwave-induced plasmas studied by power interruption experiments

Excitation balances and transport properties in atmospheric microwave-induced plasmas studied by power interruption experiments

Inductively Coupled Plasma/Microwave-Induced Plasma Tandem Source for Atomic Emission Spectroscopy

Fundamental Principles of Inductively Coupled Plasmas

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