Spark emission spectra

Figure 8.4 Reproducibility of sliding spark emission spectra taken at different sites on the surface of an ABS sample containing Cd and Zn. A Zn I 213.86 nm B Cd II 214.44 nm C Cd II 226.50 nm D C III 229.68 nm E Cd I 228.80 nm. After Golloch and Siegmund [154]. Reproduced from A. Golloch and D. Siegmund, Fresenius Z. Anal. Chem., 358, 804-811 (1997), by permission of Springer-Verlag, Copyright (1997)...

Previous experience in arc and spark emission spectroscopy has revealed numerous spectral overlap problems. Wavelength tables exist that tabulate spectral emission lines and relative intensities for the purpose of facilitating wavelength selection. Although the spectral interference information available from arc and spark spectroscopy is extremely useful, the information is not sufficient to avoid all ICP spectral interferences. ICP spectra differ from arc and spark emission spectra because the line intensities are not directly comparable. As of yet, there is no atlas of ICP emission line intensity data, that would facilitate line selection based upon element concentrations, intensity ratios and spectral band pass. This is indeed unfortunate because the ICP instrumentation is now capable of precise and easily duplicated intensity measurements. 

The continuous source is quite useful for certain purposes if it is intense and a monochromator of high resolution is available. Photographic recording of absorption spectra can be made in the same manner as arc or spark emission spectra are recorded. In this manner atomic absorption spectra are readily available for the study of a number of spectral absorption lines, in contrast to the single-line absorption usually obtained with a hollow cathode source. 

The original OES instruments, dating from the 1930s but used consistently from the 1950s, used a spark source to excite the emission spectrum, which usually consisted of a graphite cup as one electrode, and a graphite rod as the other. The sample (solid or liquid) was placed inside the cup and the graphite rod lowered until it was close to the cup. The sample was then vaporized by... 

The optical emission spectrum of technetium is uniquely characteristic of the element " with a few strong lines relatively widely spaced as in the spectra of manganese, molybdenum and rhenium. Twenty-five lines are observed in the arc and spark spectra between 2200 and 9000 A. Many of these lines are free from ruthenium or rhenium interferences and are therefore useful analytically. Using the resonance lines of Tc-I at 4297.06, 4262.26, 4238.19, and 4031.63 A as little as 0.1 ng of technetium can be reliably determined. 

In the emission spectrum analysis, a small piece of material to be analyzed is heated (burned) in an electric arc or spark and its spectrum recorded by means of a spectrometer. By comparing the wave lengths of the spectrum with.chose produced by known materials, it is possible to determine rapidly the composition of the sample... 

It has now been established that the emission spectrum of the element lies in the ultraviolet. Prominent lines in the are and spark spectra are found at A =2555-7, 2554-0, 2536-4, 2534-75 A. These are also seen in the spectra from the vapour in a Geissler tube, and in addition other lines at 2497-3 and 2484-1.3 A photographic record of the condensed spark spectrum showed lines at 2555-0, 2553-3, 2535-6, 2534 A.4... 

In 1802 Wollaston discovered, in the continuum emission spectrum of the sun, dark lines which were later studied in detail by Frauenhofer. He observed about 600 lines in the sun s spectrum and named the most intensive of them by the letters from A to H. In 1820 Brewster explained that these lines originate from the absorption processes in the sun s atmosphere. Similar observations were made by several researchers in the spectra of stars, flames, and sparks. In 1834 Wheatstone observed that the spectra produced with a spark depended on the electrode material used. Angstrom in turn made the observation that spark spectra were also dependent on the gas surrounding the electrodes. The study of flame spectra became much easier after the discovery of the Bunsen burner in 1856. 

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