Page 16 - An Introduction to Analytical Atomic Spectrometry - L. Ebdon

Page 1

1
Overview of Analytical Atomic Spectrometry.

1.1 Historical

1.1.1 Optical Spectroscopy

Spectroscopy is generally considered to have started in 1666, with Newton's discovery of the solar
spectrum. Wollaston repeated Newton's experiment and in 1802 reported that the sun's spectrum was
intersected by a number of dark lines. Fraunhofer investigated these lines—Fraunhofer lines—further
and, in 1823, was able to determine their wavelengths.

Early workers had noted the colours imparted to diffusion flames of alcohol by metallic salts, but
detailed study of these colours awaited the development of the premixed air-coal gas flame by Bunsen.
In 1859, Kirchhoff showed that these colours arose from line spectra due to elements and not
compounds. He also showed that their wavelengths corresponded to those of the Fraunhofer lines.
Kirchhoff and Fraunhofer had been observing atomic emission and atomic absorption, respectively.

Atomic absorption spectroscopy (AAS), atomic emission spectroscopy (AES) and later atomic
fluorescence spectroscopy (AFS) then became more associated with an exciting period in astronomy
and fundamental atomic physics. Atomic emission spectroscopy was the first to re-enter the field of
analytical chemistry, initially in arc and spark spectrography and then through the work of Lunegardh,
who in 1928 demonstrated AES in an air-acetylene flame using a pneumatic nebulizer. He applied this
system to agricultural analysis. However, the technique was relatively neglected until the development
of the inductively coupled plasma as an atom cell, by Greenfield in the UK and Fassel in the USA,
which overcame many of