A miniature planar magnetron glow discharge source for analysis of submicroliter volume aqueous samples using atomic emission spectroscopy

A miniature planar magnetron glow discharge source with a chamber volume of 60 ml has been designed and evaluated for the analysis of less than 1 μl of aqueous samples by atomic emission spectroscopy. Limits of detection for magnesium, silver, boron, europium and copper in the presence of a magnetic field are observed to be 3 to 40 times lower than for the source without a magnetic field when the measurements are made under the compromised discharge conditions for each type of source. Emission intensity in the presence of the magnetic field is found to increase as a square function of the discharge current. The improved detection limits for the magnetically enhanced glow discharge source are attributed to the increased current density of the discharge in the presence of the magnetic field which formed a plasma ring localized above the cathode surface. An RSD in the range 15–25% is observed for these measurements.     

Internal glow discharge-fourier transform ion cyclotron resonance mass spectrometry

A glow discharge (GD) ion source has been developed to work within the high magnetic field of a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. Characterization of this source revealed that the optimum operating voltage, pressure, and current are significantly lower than those for normal glow discharges. The sputter rate was lowered to 1/30th of that found with a normal glow discharge source operated external to the high magnetic field region. Operation of the GD source closer to the FTICR analyzer cell than with previous experimental designs resulted in improved ion transport efficiency. Preliminary results from this internal GD source have established detection limits in the low parts per million range for selected elemental species.     

Powering the analytical glow discharge

The glow discharge may be powered by direct current (dc), radio frequency (rf) and pulsed discharge sources. Each has specific advantages and special features that should be considered by analysts using the various forms of glow discharge spectroscopy. This paper reviews some of the factors that contribute to the selection of a power source for the glow discharge.     

Powering the analytical glow discharge

The glow discharge may be powered by direct current (dc), radio frequency (rf) and pulsed discharge sources. Each has specific advantages and special features that should be considered by analysts using the various forms of glow discharge spectroscopy. This paper reviews some of the factors that contribute to the selection of a power source for the glow discharge.     

A glow discharge lamp with supplementary excitation by a radio—frequency discharge-preliminary measurements

The emission radiant output of an ordinary glow discharge plasma was increased by several factors through secondary inductively coupled RF excitation produced by an external coil and a 136.2MHz oscillator. The gain factor was determined at several glow discharge currents and voltages in copper alloys and cast iron samples. Improved linear calibration curves were obtained because the RF-boosted glow discharge source decreased the effect of self-absorption.     

Glow discharge electron impact ionization source for miniature mass spectrometers

A glow discharge electron impact ionization (GDEI) source was developed for operation using air as the support gas. An alternative to the use of thermoemission from a resistively heated filament electron source for miniature mass spectrometers, the GDEI source is shown to have advantages of long lifetime under high-pressure operation and low power consumption. The GDEI source was characterized using our laboratory's handheld mass spectrometer, the Mini 10. The effects of the discharge voltage and pressure were investigated. Design considerations are illustrated with calculations. Performance is demonstrated in a set of experimental tests. The results show that the low power requirements, mechanical ruggedness, and quality of the data produced using the small glow discharge ion source make it well-suited for use with a portable handheld mass spectrometer.     

Optimization of an rf-powered magnetron glow discharge for the trace analysis of glasses and ceramics

A radiofrequency (rf) powered planar magnetron glow discharge ion source has been designed and coupled to a double-focusing mass spectrometer. Superposition of the electrical field of the plasma in the cathode dark space and the magnetic field obtained from a ring-shaped magnet located directly behind the sample (cathode) form the electron traps and enhance the sputtering and ionization efficiency of the ion source. In order to establish optimum conditions for the trace analysis of nonconducting materials, mass spectrometric studies have been carried out on the ion signal intensities and energy distributions of analyte and discharge gas ions depending on pressure.     

Optimization of an rf-powered magnetron glow discharge for the trace analysis of glasses and ceramics

A radiofrequency (rf) powered planar magnetron glow discharge ion source has been designed and coupled to a double-focusing mass spectrometer. Superposition of the electrical field of the plasma in the cathode dark space and the magnetic field obtained from a ring-shaped magnet located directly behind the sample (cathode) form the electron traps and enhance the sputtering and ionization efficiency of the ion source. In order to establish optimum conditions for the trace analysis of nonconducting materials, mass spectrometric studies have been carried out on the ion signal intensities and energy distributions of analyte and discharge gas ions depending on pressure.     

Plasma diagnostics of an analytical Grimm-type glow discharge in argon and in neon: Langmuir probe and optical emission spectrometry measurements

Comparative investigations were performed on a Grimm-type glow discharge source by Langmuir probe measurements and by optical emission spectrometry. The Langmuir probe measurements yielded electron temperatures and number densities of electrons, whereas the optical emission spectrometry measurements resulted in data for excitation and ionization temperatures of different species. The results confirm that there is no local thermal equilibrium in the discharge plasma. The operating conditions of the glow discharge source and also the working gas and the cathode material were varied to investigate their influence on the plasma parameters. The outcome of the plasma diagnostics will be used to improve the modelling of relevant excitation and ionization processes by computer simulation. The major physical processes in the low pressure glow discharge plasma should be better understood if the analytical capability of this spectrochemical excitation and ionization source has to be further enhanced.     

Radio-frequency glow discharge ion source for high resolution mass spectrometry

A radio-frequency powered glow discharge ion source has been developed for a double-focusing mass spectrometer. The sputtering and ionization of conducting, semiconducting and insulating materials have been realized using a 13.56 MHz generator to supply the discharge operating potential. The glow discharge ion source operates stably at argon pressures of 0.1–1 hPa and radio frequency powers of 10–50 W. The influence of discharge parameters and gas inlet system on sputtering rates and ion signal intensities for semi-insulating gallium arsenide wafers has been investigated.     

Direct determination of trace amounts of acetic acid using a novel ambient glow discharge ion source

<正>A novel ambient glow discharge ion source with improved line-cylinder electrodes is put forward and designed in this paper.The diameters of inner and outer electrodes are 0.16 and 4 mm respectively.With a special assembly method,a perfect coaxiality of the two electrodes is obtained.From the gas discharge experiment,it can be seen that the discharge can stably work in normal glow discharge mode.The operating currents of the ion source are in an order of milliamperes and can generate a much larger number and wider variety of reagent ions.The MS experiment shows that the ion source has higher detection sensitivity.     

Application of a modulated Grimm-type glow discharge plasma as primary light source for simultaneous reading atomic absorption spectrometry

Summary The Grimm-type glow discharge lamp (GDL) working in a modulated way can be used as primary light source for atomic absorption measurements. The number of element radiations is given by the composition of the target (sample on GDL) which becomes sputtered. Its composition can be adopted to the analytical problem to be solved. It is easy to change the target.The glow discharge source generated at relatively low power (10–24 W) is burning stable for >20 min on the same spot. This is time enough to operate atomic absorption measurements of 10 samples simultaneously, for example, by using the normal flame technique or the graphite tube furnace or the atomsource sputter method to generate atoms of the sample material. The monochromator device of an AA spectrometer has to be replaced by a polychromator one.The spectral behaviour of the glow discharge source compared to that of the hollow cathode lamps of the elements studied is described here by using a double beam two channel AA spectrometer for simultaneous reading of both the signals. In most cases the glow discharge source is the better one. Home-made targets are used to measure first analytical results.

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Einsatz einer modulierten Glimmentladungslampe als Primärlichtquelle zur simultan messenden Atomabsorptionsspektrometrie

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We have to thank the Spectruma company and Bernhard Bogdain especially for supporting this work.     

Reducing the Background Level of a Mass-Spectrometric Hollow Cathode Glow Discharge Ion Source

Glow discharge mass spectrometry was used for the direct elemental analysis of solids with gas inclusions. The background signal of a glow discharge, which converts the analyte into ions, is higher than the background signals of other plasma sources by several orders of magnitude. The structure and sources of background contamination were analyzed in this work. It was found that hydrocarbon and water impurities, which are adsorbed on the inner surfaces of the discharge chamber, make the major contribution to the background signal of a glow discharge source. A glow discharge plasma licked the walls of the discharge chamber to desorb contaminants. We proposed using a hollow cathode with a holed cap arranged at the vertex. On the appearance of a discharge, a plasma plug is formed in the cathode hole in front of the orifice. This plasma plug prevents a gas flow from the hole to the source chamber. As a result, a gas pressure drop is formed whose magnitude depends on the orifice diameter in the cap.     

Determination of Minor Aluminum and Nickel in Brass Sample with Magnetic Field Enhanced Glow Discharge Optical Emission Spectrometry

Glow discharge atomic spectrometry, includes principally glow discharge optical emission spectrometry (GD-OES) and GD mass spectrometry, has been widely applied in direct solid sample determination and surface depth analysis. There have been numerous methods adopted to enhance the emission signal in a GD-OES without losing the advantage of narrow spectral lines by using what is known as boosted GD sources, especially microwave discharge and magnetic field enhanced techniques. The addition of a magnetic field to the GD volume is an attractive option because it does not require much modification to the original source configuration, in addition,the presence of magnetic field lengths the drift path of electrons from plasma region to the anode,and therefore strengthens the sputtering, excitation, and ionization processes that good for signal generation.     

辉光放电灯在分析中的应用

辉光放电灯（GDL）作为光源被广泛应用于固体样品的直接分析中,文章综述了GDL的发展过程、类型及其在分析中的应用。     

Chemical ionization mass spectrometry using a glow discharge ion source combined with a nebulizer sampling system

A glow discharge chemical ionization (CI) source equipped with a pneumatic nebulizer for sample introduction has been constructed. A comparative study of the discharge CI and conventional CI by electron impact from a hot filament is made for various polar compounds using oxygen-containing reagents such as water and methanol. The potential utility of the discharge ion source to liquid chromatography/mass spectrometry is also discussed.     

双电离源(辉光放电/激光溅射电离)四极杆质谱仪的研制

本研究将辉光电离源与激光溅射电离源巧妙地结合在同一台仪器中,使固体样品在离子源腔体中既能辉光电离,也能激光电离;并且使用同一质量分析器,两种离子源的结果可以相互比对,进而得到更为准确的分析结果.此仪器主要由真空系统、离子源、离子传输系统、四极杆质量分析器及检测与数据采集系统等组成.实验中分别用两种离子源测试了标准样品SRM 1262b,并获得了半定量结果.结果表明,仪器具有定性能力强,分析速度快,检测灵敏度高等优点,对固体样品元素分析的检出限可达μg/g量级.实验表明,激光溅射电离质谱的性能优于辉光放电质谱.     

射频供能辉光放电原子发射光谱分析导体的基本特性

自行设计组装了射频供能辉光放电原子发射光谱仪器(rf-GD-AES),并对其分析导体试样的基本特性(包括光源的稳定性、电学特性和光谱特性)进行了研究。在此基础上建立了rf-GD-AES分析导电试样的方法,并用于铜合金标准样品中的A l和Mn的分析,其测定结果与标准值吻合很好,充分地显示了rf-GD-AES在固体样品直接分析中的潜力。     

Glow characterization in direct current plasma polymerization of trimethylsilane

Plasma polymerization of trimethylsilane (TMS) was carried out in a direct current (dc) glow discharge and was investigated by optical photography and plasma diagnostic techniques including optical emission spectroscopy and residual gas analysis. The nature of the glow formed in TMS discharge, which deposited plasma polymers, was significantly different from that of a simple gas such as Ar. In an Ar discharge, the dominant glow was the well known negative glow, which developed at a distinctive distance from the cathode, whereas the cathode surface remained in the dark space. In strong contrast to this situation, in TMS dc discharge the dominant or primary glow was the cathode glow, which appeared at the cathode surface. At a similar location where the Ar negative glow appeared, a very feeble glow as a secondary glow was also observed in TMS glow discharge. The deposition results and plasma diagnosis data evidently indicated that in TMS glow discharge, the cathode glow resulted from the low‐energy electron‐impact dissociation of TMS molecules that creates polymerizable species, but the negative glow was related to nonpolymerizable species such as hydrogen atoms and molecules. In this article, the cathode glow formed in glow discharges of organic compounds was designated as the dissociation glow according to its underlying plasma reactions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1042–1052, 2004     

Surface elemental mapping using glow discharge—optical emission spectrometry

A glow discharge optical-emission spectrometry source was evaluated for use in imaging elemental surface distributions. A 1.8 cm² area of a nickel–chromium alloy was sampled and copper emission was observed directly above the surface of a copper inclusion. By pulsing the glow discharge, the resolution was improved greatly over measurements using direct-current powering. Ranges of gas flows, pulse frequencies, pulse potentials, pulse widths, and pressures were explored to determine their effects on spatial resolution and were related to atom transport in the glow discharge cell. Pressure, pulse width, and pulse frequency were all found to have a significant effect on resolution.