Optimization of discharge parameters of a pin-type radio frequency glow discharge source for a quadrupole mass spectrometer system

1994 ◽  
Vol 9 (9) ◽  
pp. 1045 ◽  
Author(s):  
Charles R. Shick ◽  
Angelika Raith ◽  
R. Kenneth Marcus
Keyword(s):  
Glow Discharge ◽  
Radio Frequency ◽  
Mass Spectrometer ◽  
Quadrupole Mass ◽  
Radio Frequency Glow Discharge ◽  
Discharge Source ◽  
Mass Spectrometer System ◽  
Discharge Parameters ◽  
Spectrometer System ◽  
Glow Discharge Source

Optimization of Discharge Parameters for a Flat-Type Radio-Frequency Glow Discharge Source Coupled to a Quadrupole Mass Spectrometer System

1996 ◽  
Vol 50 (4) ◽  
pp. 454-466 ◽  
Author(s):  
Charles R. Shick ◽  
R. Kenneth Marcus
Keyword(s):  
Glow Discharge ◽  
Radio Frequency ◽  
Mass Spectrometer ◽  
Ion Beam ◽  
Source Parameters ◽  
Ionization Source ◽  
Radio Frequency Glow Discharge ◽  
Mass Spectrometer System ◽  
Discharge Parameters ◽  
Spectrometer System

A radio-frequency (rf)-powered glow discharge (GD) atomization/ionization source for nominally flat sample types (>6 mm o.d.) has been designed and coupled to a commercial GD mass spectrometer system, the VG GloQuad. This source was evaluated and optimized for conducting as well as nonconducting samples. A parametric study has been conducted on this rf-GDMS system with respect to discharge power, Ar flow (cell pressure), limiting orifice plate (anode) diameter, and ion sampling distance. Analytical characteristics under the optimized source parameters—including stabilization times (5 min for conducting samples, 60 min for nonconducting samples); repeatability (overall internal <2% RSD, overall external <8% RSD employing ion beam ratios); quantification; and detection limits—were evaluated for both conducting and nonconducting samples.

Investigation of Sample Atomization Using a Power-Modulated Radio-Frequency Glow Discharge Source

1996 ◽  
Vol 50 (3) ◽  
pp. 366-376 ◽  
Author(s):  
Mark Parker ◽  
R. Kenneth Marcus
Keyword(s):  
Glow Discharge ◽  
Radio Frequency ◽  
Average Power ◽  
Atomic Absorption Spectrophotometry ◽  
Orifice Diameter ◽  
Continuous Mode ◽  
Radio Frequency Glow Discharge ◽  
Discharge Source ◽  
Duty Cycles ◽  
Glow Discharge Source

A power-modulated (pulsed), radio-frequency glow discharge source by atomic absorption spectrophotometry (rf-GD-AAS) atomizer was used to evaluate the roles of applied power, pressure, orifice diameter, duty cycle, and power-on time in the production of gas-phase sample atoms. As expected, the response of the modulated rf-GD-AAS source generally followed the same trends as those exhibited by the more common continuous-powering scheme. The effects of discharge power and pressure on the observed plasma emission and absorbance transients are presented. Use of small duty cycles and higher instantaneous powers, thus keeping the same overall average power as in the continuous mode, was shown to increase the production of ground-state atoms. However, using very high instantaneous powers may more efficiently populate excited states of the atomic species, thus decreasing the observed absorption signal for resonant transitions. Individual pulse transients were shown to be distorted if the plasma “on” times approached periods down to 2 ms. Plasma stabilization times for measurements taken in the “dark” portion of the pulse cycle (i.e., after pulse termination) were comparable to those obtained in the continuous mode (on the order of a few seconds) with the use of the same source and sample. Calibration curves were used to investigate the analytical utility of different temporal regions of the absorption transients with comparisons made between the plasma “on” and “off” portions of the cycle in the quantification of continuous plasma operation.

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