Continuum-source atomic absorption

Figure 21-19 Graphite furnace absorption spectrum of bronze dissolved in HN03. [From B. T. Jones. B. W Smith, and J. D. Winetordner. Continuum Source Atomic Absorption Spectrometry in a Graphite Furnace with Photodiode Array Detection. Anal. Chem. 1989,61. 1670.]...

H. Becker-Ross, S. Florek, U. Heitmann, R. Weisse, Influence of the spectral bandwidth of the spectrometer on the sensitivity using continuum source atomic absorption spectrometry, Fresenius J. Anal. Chem., 355 (1996), 300. 

U. Heitmann, S. Florek, M. D. Huang, Sensitivity, linearity and working range of a modem continuum-source atomic absorption spectrometer, Seventh Rio Symposium on Atomic Spectrometry, Book of Abstracts, Florianopolis, SC, Brazil, 7-12 April 2002,... 

Welz B, Becker-Ross H, Florek S, Heitmann U, Vale MGR. Braz J. High-resolution continuum-source atomic absorption spectrometry - what can we expect Chem Soc 2003 14 220-9. 

J.A. Rust, J.A. Nobrega, C.P. CaUoway Jr., and B.T. Jones. Advances with tungsten coil atomizers continuum source atomic absorption and emission spectrometry. Spectrochimica Acta Part B 60 589-598, 2005. 

Historical Development of Continuum Source Atomic Absorption Spectrometry... 

D.L.G. Borges, Direct determination of Lead in Biological Samples by High-Resolution Continuum Source Atomic Absorption Spectrometry, Master thesis, Uni-versidade Federal de Santa Catarina, Florianopolis, Brazil, 2005. 

A.F. Silva, D.L.G. Borges, F.G. Lepri, B. Welz, A.J. Curtius, U. Heitmann, Determination of cadmium in coal using solid sampling graphite furnace high-resolution continuum source atomic absorption spectrometry, calibration against aqueous standards and Ir as a permanent modifier, J. Anal. Atom. Spectrom. (2005) submitted. 

Continuum-source atomic absorption spectrometry in the case of a high-... 

ScHUETZ M., Murphy J., Fields R. F. and Haenly J. M. (2000) Continuum source-atomic absorption spectrometry using a two-dimensional charge-coupled device, Spectrochim. Acta, Part B 55 1895-1912. 

Florek S. and Heitmann U. (2002) Investigation of interferences in the determination of thallium in marine sediment reference materials using high-resolution continuum-source atomic absorption spectrometry and electrothermal atomization, Spectrochim. Acta, Part B 57 1043—1055. 

Figure 10.6. Atomic absorption with A) a sharp-line source and (B) a spectral-continuum source. AA = absorption line half-width AA, = source line half-width S = spectral bandwidth of monochromator. Adapted from G. D. Christian and F. J. Feldman, Atomic Absorption Spectroscopy Applications in Agriculture, Biology, and Medicine, New York Wiley-Interscience, 1970, p 58, by permission of John Wiley and Sons.

B. Welz, S. Mores, E. Carasek, M. G. R. Vale, M. Okruss and H. Beeker-Ross, High-resolution continuum source atomic and molecular absorption spectrometry - a review, Appl. Spectrosc. Rev., 2010, 45, 327-354. 

Equation 10.1 has an important consequence for atomic absorption. Because of the narrow line width for atomic absorption, a continuum source of radiation cannot be used. Even with a high-quality monochromator, the effective bandwidth for a continuum source is 100-1000 times greater than that for an atomic absorption line. As a result, little of the radiation from a continuum source is absorbed (Pq Pr), and the measured absorbance is effectively zero. Eor this reason, atomic absorption requires a line source. 

Atomic fluorescence spectrometry has a number of potential advantages when compared to atomic absorption. The most important is the relative case with which several elements can be determined simultaneously. This arises from the non-directional nature of fluorescence emission, which enables separate hollow-cathode lamps or a continuum source providing suitable primary radiation to be grouped around a circular burner with one or more detectors. 

Spectral line sources are used as light sources in atomic absorption instruments rather than the continuum sources used for UV-VIS molecular absorption instruments, and several atomic emission techniques require no light source at all apart from the thermal energy source. 

In recent years, it has been shown that the construction of atomic absorption spectrometers using continuum sources is possible, if somewhat expensive and complicated. So far, commercial manufacturers have not yet produced instruments of this type, which have remained the creations of a... 

Relative atomic absorption of light from continuum and line sources. 

U. Heitmann, M. Schutz, H. Becker-Ross and S. Florek, Measurements on the Zeeman-splitting of analytical lines by means of a continuum source graphite furnace atomic absorption spectrometer with a linear charge coupled device array, Spectrochim. Acta Part B, 51, 1996, 1095-1105. 

Figure 14.5—Comparison of transmit ted intensities in atomic absorption with a continuum source (a and b) and with a tamp that emits spectraI lines (c and d). The square region shows the wavelength interval percieved by the photomultiplier tube (PMT). The PMT signal is proportional to the area of the white parts in the squares. In this way, the resolution is in the source , as expressed by Walsh, who is considered to be one of the pioneers of atomic absorption.

Atomic Fluorescence Spectrometry. A spectroscopic technique related to some of the types mentioned above is atomic fluorescence spectrometry (AFS). Like atomic absorption spectrometry (AAS), AFS requires a light source separate from that of the heated flame cell. This can be provided, as in AAS, by individual (or multielement lamps), or by a continuum source such as xenon arc or by suitable lasers or combination of lasers and dyes. The laser is still pretty much in its infancy but it is likely that future development will cause the laser, and consequently the many spectroscopic instruments to which it can be adapted to, to become increasingly popular. Complete freedom of wavelength selection still remains a problem. Unlike AAS the light source in AFS is not in direct line with the optical path, and therefore, the radiation emitted is a result of excitation by the lamp or laser source. 

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