Sources atomic spectroscopy

Table 2 Bibliography from 1980 to 1990. (Source Atomic Spectroscopy)...

The predorninant method for the analysis of alurninum-base alloys is spark source emission spectroscopy. SoHd metal samples are sparked direcdy, simultaneously eroding the metal surface, vaporizing the metal, and exciting the atomic vapor to emit light ia proportion to the amount of material present. Standard spark emission analytical techniques are described in ASTM ElOl, E607, E1251 and E716 (36). A wide variety of weU-characterized soHd reference materials are available from major aluminum producers for instmment caUbration. 

W.C. Martin, Sources of Atomic Spectroscopy Data for Astrophysics , in PL. Smith and W. L. Wiese (eds.), Atomic and Molecular Data for Space Astronomy Needs, Analysis and Availability, Springer, Berlin, 1992. 

Perhaps the most noticeable difference in instrumentation is the sample container used for atomic spectroscopy. This container is the source of the thermal energy needed for the conversion of ions in solution to atoms in the gas phase (and hence is called an atomizer) and in no way resembles a simple cuvette. Recall, for example, the brief discussion and photograph of the flame container in Section 7.5. 

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... 

The minor and trace elements in coals are currently determined by several techniques, the most popular of which are optical emission and atomic absorption spectroscopy. Neutron activation analysis is also an excellent technique for determining many elements, but it requires a neutron source, usually an atomic reactor. In addition, x-ray fluorescence spectroscopy, electron spectroscopy for chemical analyses (ESCA), and spark source mass spectroscopy have been successfully applied to the analyses of some minor and trace elements in coal. 

Mass balance measurements for 41 elements have been made around the Thomas A. Allen Steam Plant in Memphis, Tenn. For one of the three independent cyclone boilers at the plant, the concentration and flow rates of each element were determined for coal, slag tank effluent, fly ash in the precipitator inlet and outlet (collected isokinetically), and fly ash in the stack gases (collected isokinetically). Measurements by neutron activation analysis, spark source mass spectroscopy (with isotope dilution for some elements), and atomic adsorption spectroscopy yielded an approximate balance (closure to within 30% or less) for many elements. Exceptions were those elements such as mercury, which form volatile compounds. For most elements in the fly ash, the newly installed electrostatic precipitator was extremely efficient. 

The flameless atomic absorption method has a reproducibility of about 2% or better for homogeneous specimens. Checks (3) between AA and NAA (with radiochemical separation after irradiation) and isotope dilution spark source mass spectroscopy on thoroughly homogenized tuna fish and Bureau of Mines round-robin coal specimens indicate good agreement between the methods. (0.425 0.9%, 0.45 3.5%, and 0.45 4.4% for tuna by AA, NAA, and SSMS, respectively, and 1.004 is the average ratio of NAA to AA results for five coal samples.) The similar results indicate that the technique used in sample preparation... 

The dialogue between users and providers of atomic data is a two-way conversation, with atomic physicists beginning to view astrophysical and laboratory plasmas as unique sources of new information about the structure of complex atomic species. A number of monographs on theoretical atomic spectroscopy cowritten by theoreticians and astrophysicists and dedicated to astrophysicists also contribute to better mutual understanding [18, 320]. 

Atomic spectroscopy continues to be one of the most important subjects of contemporary physics. Spectra are fundamental characteristics of atoms and ions, and are the main source of information on their structure and properties. Modem atomic spectroscopy studies the structure and properties of practically every atom of the Periodical Table as well as of ions of any ionization degree. The book contains a large number of new results, which have been mainly published in Russian and are therefore almost unknown to western scientists. 

Atomic absorption remained the technique of choice until relatively recently. However, with the introduction of plasma sources, atomic emission, in the form of inductively coupled plasma spectroscopy, has made a comeback. This development is now receiving historical attention, and was the subject of a symposium held in 1999. Papers discussed atomic emission analysis prior to 1950,206 the fact that emission techniques developed continuously, even in the period when absorption methods were dominant,207 and the development of the plasma sources on which the new techniques depend.208 Also discussed was the powerful hyphenated technique of ICP-MS,209 and the history of one of the leading manufacturers of atomic emission instruments.210... 

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-... 

LSafety note In atomic spectroscopy, thej., fiu se of high- pressure gas sources, e.g.L.- . Ry]iiiders,3affB )particWar[y,haza2lou sr. Alvyaysjoirsolt a-demonstrator otC Itechpician before use - ... 

Safety note in atomic Spectroscopy, the use of. high-pressure gas sources, e.g. cylinders, an be particularly hazardous.. Always consult a demonstrator or technician before use. ... 

The conversion of the sample into an atomic vapor and its subsequent, excitation are the most important and difficult stages in atomic spectroscopy. The process consists of three distinct phases presentation of the sample to the energy source, atomization, and finally excitation of the atomic vapor. The ideal system is one in which the sample is completely converted into an atomic vapor in a perfectly reproducible manner, the vapor produced is of high atomic density with no interactions within the vapor which could lead to impairment of the emission, absorption, or fluorescence. 

The number of applications of atomic techniques based on solid or slurry sampling is so large that only a comparatively minute fraction is discussed in this section. Interested readers are referred to the biannual reviews of Analytical Chemistry and the atomic spectroscopy update in the Journal of Analytical Atomic Spectrometry, among other sources, for more extensive information. A specific review of the uses of graphite atomizers modified with high-melting carbides has been published by Volynsky that includes virtually all metals determined in this manner [74]. 

Figure 3.17 Graphical illustration of measurement uncertainty for individual sources with an analytical method for metal analysis using atomic spectroscopy...

In the application of atomic spectroscopy to FIA the sample plug is carried first to the nebuliser and eventually to the plasma source for excitation and atomisation for detection to give signal responses for the corresponding concentrations of analyte, as shown in Figure 7.3. 

In addition to the continuum sources just discussed, line sources are also important for use in the UV/visible region. Low-pressure mercury arc lamps are very common sources that are used in liquid chromatography detectors. The dominant line emitted by these sources is the 253.7-nm Hg line. Hollow-cathode lamps are also common line sources that are specifically used for atomic absorption spectroscopy, as discussed in Chapter 28. Lasers (see Feature 25-1) have also been used in molecular and atomic spectroscopy, both for single-wavelength and for scanning applications. Tunable dye lasers can be scanned over wavelength ranges of several hundred nanometers when more than one dye is used. 

For a detailed discu.ssion of the various plasma sources, see S. J. Hill. Inductively Coupled Plasma Spectrometry and Its Applications. Boca Raton, FL CRC Press, 1999. Inductively Coupled Plasmas in Analytical Atomic Spectroscopy, 2nd ed. A. Montaser and D. W. Golightly. Eds. New York Wiley-VCH Publishers, 1992 Inductively Coupled Plasma Mass Spectrometry. A. Montaser, Ed. New York Wiley, 1998 Inductively Coupled Plasma Emission Spectroscopy. Parts I and 2. P. W. J. M. Bouraans. Ed. New York Wiley. 1987. 

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. 

In the early days of atomic spectroscopy, dc and ac arcs and high-voltage sparks were popular for use in excitation of atomic emission. Such sources have almost entirely been replaced by the ICP. 

Burners Sources of heat for laboratory operations or for flame atomic spectroscopy. 

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