Electron Number Density Measurements in Ar and Ar-N₂ Inductively Coupled Plasmas

Abstract

The emission spectrum of the series limit of Al was used to estimate the electron number densities ( n e) in inductively coupled Ar or Ar-N2 plasmas (ICP). The spectra of the series limit were recorded either with a silicon-intensified target vidicon detector or by a computer-controlled, scanning spectrometer. Background stripping was performed on the spectra recorded by both instruments to enhance signal recovery. Under comparable experimental conditions, the n e values in the Ar-supported ICP were higher than those observed in Ar-N2 plasma, when pure N2 was used in the outer flow. However, the n e value of the Ar ICP under the conditions commonly used in analytical laboratories (15 mm observation height and 1200 W forward power) was comparable to that found in pure N2 outer flow, Ar-N2 plasmas operated under conditions (5 mm observation height and 3000 W forward power) suitable for exciting spectral lines of high excitation energies. Whereas the use of higher, carrier gas flows tended to reduce the n e values of the Ar ICP substantially, this trend was not observed for the pure N2 outer flow Ar-N2 plasma.

Spectroscopic Characteristic and Analytical Capability of Ar-N2 Inductively Coupled Plasma in Axially Viewing Optical Emission Spectrometry

“…The improved LODs were observed for elements such as As, Bi, Cd, P, S and Zn whose excitation energies were relatively higher viewing Ar-N2 ICPOES reported previously. [4][5][6][7][8][9][10][11][12][13][14] From these results, the Ar-N2 ICP could be useful as an optional excitation and ionization source in axially viewing ICPOES, especially for those elements with relatively higher excitation and ionization energies.…”

“…2,3 In order to improve the analytical sensitivity as well as the analytical performance for either ICPOES or ICPMS, many examinations on the alternative plasma sources have been carried out instead of the Ar ICP as standard ICP. In the 1980's, mixed-gas ICPs such as Ar-N2 ICP, [4][5][6][7][8][9][10][11][12][13][14] Ar-O2 ICP, [10][11][12]14,15 Ar-He ICP, 10,11,13,15 Ar-Air ICP 10,11 and Ar-H2 ICP, 13 molecular-gas ICPs such as N2 ICP [16][17][18] and O2 ICP, [18][19][20][21][22] and He ICP, [23][24][25][26][27][28] were examined to achieve further improvement in the analytical sensitivity of elements instead of the standard (Ar) ICPOES. Since radial viewing ICPOES was mainly used in those days, most of the mixed-gas ICPs was examined in radial viewing OES.…”

Evaluation of the detection capability of a high power nitrogen microwave-induced plasma for both atomic emission and mass spectrometry

“…The instrumentation used for the AES work has been described conditions for each instrument. The detection limits (3s) were in a previous paper51 and the instruments for N 2 -MIP-MS established as the detection capability for both plasma systems and Ar-ICP-MS were a P-6000 (Hitachi, Ibaraki, Japan) and using a total of 55 wavelengths (atom and ion lines) for 21 an HP-4500 (Yokogawa Analytical Systems, Tokyo, Japan), elements for AES and a total of 38 m/z values for 22 elements respectively. The plasma operating conditions and the measurefor MS.…”

A dynamic model for the elucidation of a mechanism of analyte transformation in an inductively coupled plasma

“…The LTE approach is advantageous in the sense that the plasma can be characterized with either or both of the two measurable parameters, i.e., temperature and electron density, thus providing a basis for theory-experiment comparison. Unfortunately, many diagnostical studies have indicated that LTE does not exist throughout the ICP (2, 7, [9][10][11]16,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43], rendering it inappropriate to mechanistic elucidation of analyte excitation. Furthermore, it treats the portion of plasma under investigation as a closed system, whereas the real plasma is everywhere dynamic and open.…”