Glow atomic emission spectroscopy

Bengtson A. (1985) A contribution to the solution of the problem of quantification in surface analysis work using glow discharge atomic emission spectroscopy, Spectrochim Acta, Part B 40 631-639. 

The following ionization sources are used mainly in inorganic (atomic) MS, where the elemental composition of the sample is desired. The glow discharge (GD) and spark sources are used for solid samples, while the inductively coupled plasma (ICP) is used for solutions. All three sources are also used as atomic emission spectroscopy sources they are described in more detail with diagrams in Chapter 7. 

Fig. 12.27 Schematic diagram of a discharge cell for RF-glow discharge atomic emission spectroscopy.

Use of glow-discharge and the related, but geometrically distinct, hoUow-cathode sources involves plasma-induced sputtering and excitation (93). Such sources are commonly employed as sources of resonance-line emission in atomic absorption spectroscopy. The analyte is vaporized in a flame at 2000—3400 K. Absorption of the plasma source light in the flame indicates the presence and amount of specific elements (86). 

Inductively Coupled and Microwave Induced Plasma Sources for Mass Spectrometry 4 Industrial Analysis with Vibrational Spectroscopy 5 Ionization Methods in Organic Mass Spectrometry 6 Quantitative Millimetre Wavelength Spectrometry 7 Glow Discharge Optical Emission Spectroscopy A Practical Guide 8 Chemometrics in Analytical Spectroscopy, 2nd Edition 9 Raman Spectroscopy in Archaeology and Art History 10 Basic Chemometric Techniques in Atomic Spectroscopy... 

During the 20-plus years that mass spectrometrists lost interest in glow discharges, optical spectroscopists were pursuing these devices both as line sources for atomic absorption spectroscopy and as direct analytical emission sources [6-10]. Traditionally, inorganic elemental analysis has been dominated by atomic spectroscopy. Since an optical spectrum is composed of lines corre-... 

Graphite furnace AAS Atomic fluorescence spectroscopy Inductively-coupled-plasma optical-emission spectroscopy Glow-discharge optical-emission spectroscopy Laser-excited resonance ionization spectroscopy Laser-excited atomic-fluorescence spectroscopy Laser-induced-breakdown spectroscopy Laser-induced photocoustic spectroscopy Resonance-ionization spectroscopy... 

Many other types of atomization devices have been used in atomic spectroscopy. Gas discharges operated at reduced pressure have been investigated as sources of atomic emission and as ion sources for mass spectrometry. The glow discharge is generated between two planar electrodes in a cylindrical glass tube filled with gas to a pressure of a few torr. High-powered lasers have been employed to ablate samples and to cause laser-induced breakdown. In the latter technique, dielectric breakdown of a gas occurs at the laser focal point. 

The most common type of emission spectrometer in use today (inductively coupled plasma-optical emission spectroscopy, or ICP-OES) atomizes a sample by passing an electric current into a gas plasma that contains the sample. In these optical emission methods, the sample is heated to high temperature. At this temperature the individual elements glow with their representative colors, e.g., red for potassium, yellow for sodium. The light from the sample is focused on a monochrometer to select a wavelength appropriate for the element of interest. That light at the correct wavelength is focused on a detector that measures its intensity (Fig. 4.8). 

This chapter deals with optical atomic, emission spectrometry (AES). Generally, the atomizers listed in Table 8-1 not only convert the component of samples to atoms or elementary ions but, in the process, excite a fraction of these species to higher electronic stales.. 4, the excited species rapidly relax back to lower states, ultraviolet and visible line spectra arise that are useful for qualitative ant quantitative elemental analysis. Plasma sources have become, the most important and most widely used sources for AES. These devices, including the popular inductively coupled plasma source, are discussedfirst in this chapter. Then, emission spectroscopy based on electric arc and electric spark atomization and excitation is described. Historically, arc and spark sources were quite important in emission spectrometry, and they still have important applications for the determination of some metallic elements. Finally several miscellaneous atomic emission source.s, including jlanies, glow discharges, and lasers are presented. 

Boumans, P.W.J.M. Inductively Coupled Plasma Emission Spectroscopy,Parts 1 and 2. Wiley New York, 1987. Broekaert, J.A.C. Glow discharge atomic spectroscopy. A/ / /. Spectrosc., 49(1), 12A, 1995. 

A more precise group of methods measure the beam equivalent pressure in molecular beams near the substrate or the atom fraction of interest in the gas phase. There are several ways of doing this including electron impact emission spectroscopy (EIES), conventional ionization gauges, mass spectrometers, glow-discharge optical spectroscopy, and other methods. We will briefly consider these four in turn. 

GD-OES (glow discharge optical emission spectrometry) are applied. AES (auger electron spectroscopy), AFM (atomic force microscopy) and TRXF (transmission reflection X-ray fluorescence analysis) have been successfully used, especially in the semiconductor industry and in materials research. 

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