Atomic optical emission spectroscopy excitation sources

In general, detection limits with the KiP source are contparable to or better thait other atomic spectral procedures. Table lO-.f compares detection limits for Several of these methods. Note that more elements can be detected at levels of 10 ppb or less with plasma excitation than with other emission or absttrplion melhods. As we shall see in Chapter 11, the ICP coupled with mass spectrontetrie detection improves detection limits by two to live orders of magnitude for many elements and is thus strong competition for ICP optical emission spectroscopy. 

This chapter describes methods of observing the emission spectra of atoms, ions, and molecules using excitation sources powered by electrical energy. The common names emission spectroscopy or optical-emission spectroscopy are applied to these methods. 

Minute amounts of sample material ablated with the focused radiation of a pulsed laser are transported into an independent excitation source, e.g., inductively coupled plasma (ICP) for further atomization, excitation, or ionization. The detection of target atoms after laser ablation (LA) is performed by hyphenated techniques using optical emission or mass spectrometry LA-ICP-OES laser ablation-lCP-optical emission spectroscopy LA-ICP-MS laser ablation-l CP-mass spectrometry... 

With the exception of better optical resolution needed, the basic instrument used for atomic emission is very similar to that used for atomic absorption with the difference that no primary light source is used for atomic emission. One of the most critical components for this technique is the atomisation source because it must also provide sufficient energy to excite the atoms as well as atomise them. The earliest energy sources for excitation were simple flames, but these often lacked sufficient thermal energy to be truly effective sources. The development in 1963 and the introduction in 1970 of the first commercial inductively coupled plasma (ICP) as a source for atomic emission dramatically changed the use and the utility of emission spectroscopy (Thompson Walsh 1983). 

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. 

F.K. Fong, Nonradiative processes of rare-earth ions in crystals 317 J.W. O Laughlin, Chemical spectrophotometric and polarographic methods 341 S.R. Taylor, Trace element analysis cf rare earth elements by spark source mass spectroscopy RJ. Conzemius, Analysis of rare earth matrices by spark source mass spectrometry 377 37D. E.L. DeKalb and V.A. FasseL Optical atomic emission and absorption methods 405 37E. A.P. D Silva and V.A. Fassel, X-ray excited optical luminescence of the rare earths 441 F.W.V. Boynton, Neutron activation analysis 457... 

The analytical chemistry of rare earths has been reviewed by Banks and Klingman (1961), Loriers (1964), Ryabchikov (1959), and Ryabchikov and Ryabukhin (1964). Fassel (1961) reviewed the analytical spectroscopy of rare earth elements. In volume 4 of this Handbook chapters can be found on the chemical spectrophotometric and polarographic methods (O Laughlin 1979), spark source mass spectrometry (Conzemius 1979, Taylor 1979), optical atomic emission and absorption (DeKalb and Fassel 1979), X-ray excited optical luminescence (D Silva and Fassel 1979), neutron activation (Boynton 1979), mass spectrometric stable isotope dilution analysis (Schuhmaim and Philpotts 1979), and shift reagents and NMR (Reuben and Elgavish 1979). 

---