Spark-discharge atomization

In addition to the above-discussed techniques, some other atomization methods have also been developed for specific applications. These include, for example, solution atomization, liquefied gas atomization, and spark-discharge atomization,[881 etc. 

Volatile or volatilizable compounds may be introduced into the spectrometer via a pinhole aperture or molecular leak which allows a steady stream of sample molecules into the ionization area. Non-volatile or thermally labile samples are introduced directly by means of an electrically heated probe inserted through a vacuum lock. Numerous methods of sample ionization are available of which the most important are electron impact (El), chemical ionization (CY), field ionization (FI), field desorption (FD), fast atom bombardment (FAB), and radio-frequency spark discharge. 

Spark source SS Discharge Atomic ions Trace analysis in solid samples... 

Atomic Emission. Elemental analysis with AES had been practiced since the mid-1930s using flames and arc or spark discharges to... 

Various types of positive ions are produced in a spark discharge such as singly and multiply charged atomic ions, polymer ions and heterogeneous compound ions. A spark source mass spectrum is always characterized by singly and multiply charged ions of the... 

This emission of light from elements was reported as early as the mid-1700s and was later the basis of discovering four elements by Kirchoff and Bunsen in the mid-1800s. However, it was not until the 20th century that the technique really became a useful analytical tool. The first analytical instruments used a spark discharge to provide the energy to excite the atoms so that... 

As the sample volatilization is due to cathodic sputtering only, matrix interferences as a result of the thermochemical properties of the elements do not occur. This has been shown impressively in early comparative studies of glow discharge atomic spectrometry and spark emission spectrometry with aluminum samples (Fig. 107) [480]. It must be stated, however, that with advanced sparks, where through the use of fiber optics only those parts of the spark plasma are observed that are not involved in sample ablation, matrix interferences in the case of spark emission spectrometry are also lower. The analysis of similar alloys with different metallographic structures by glow discharge atomic spectrometry can often be carried out with one calibration. 

The early experimenters relied on the violent excitation produced by condensed spark discharges to obtain a strong atomic spectrum, but Wood [144] developed a type of discharge tube which enabled him not only to observe an almost pure atomic spectrum, but also to draw off in a side tube a stream of atomic hydrogen andjto investigate its properties. 

There are three sources coiranonly used to vaporize and excite the elements in a sample the flame, the electric arc and electric spark discharge. Flames possess the lowest excitation energy, producing a rather simple line spectra. Flame excitation will be discussed when dealing with flame photometry and atomic absorption. 

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