Atomic spectroscopy:
Atomic spectroscopy is the oldest instrumental method of elemental analysis. The origin of these methods dates back to the times of Bunsen and Kirchhoff in the mid- 19th century whereas they showed in which the optical radiation emitted from flames is features of the elements present in the flame and the intensities of the emitted radiation were dependent on the amount of elemental species present.
The atomic spectroscopic techniques are based on the transitions amongst the quantised electronic energy stages caused through the absorption of radiation through the atoms within vapour phase or by the emission of radiation by the excited atoms. Since the transitions manifest in terms of absorption, emission or fluorescence emission. Therefore, we have atomic emission, absorption and fluorescence spectroscopies. The kind of atomic spectroscopic method is determined both through the method of atomisation as well as the nature of the analyte radiation interaction. In compare to the molecular spectra, the atomic spectra consist of a number of sharp absorption lines, features of the atomic species. The signals within an atomic spectrum are also characterized in terms of the position, intensity and the band width.
Flame photometry is a technique for the determination of elements that could be simply excited and is based upon the measurement of intensity of radiation emitted, within the visible region, while a metal is introduced into a flame. A wavelength of the emitted radiation, tells us what the element is or the intensity of the radiation tells us how much of the element is present. A sensitivity of the flame photometric techniques depends on the number of excited atoms that in turn depends on the flame temperature. A flame temperature is a function of the kind of fuel and oxidant used.