Why are narrow line sources advantageous in Atomic Absorption Spectroscopy?

Answer 1

Narrow line sources are advantageous due to the simple fact that they add selectivity to the technique. If a very narrow line of a specific compound is emitted, there is a good chance that only the element that you are trying to determine will absorb that line and, therefore, you will avoid an erroneous signal due to absorption of radiation by concomitants in the atomizer, such as atoms of other elements or molecules. With that, you can also use a low or medium resolution monochromator, which will have the sole function of isolating the line of interest from other lines emitted by the source. Therefore, instruments can be simpler and, consequently, cheaper. That is basically it...

The state-of-the-art in atomic absorption spectrometry, however, consists of instruments that use continuum sources, where a single source emits radiation in all range usually used in AAS. But modifications in the instrument were necessary for that, such as the use of a high-resolution monochromator and a CCD detector. Hope that helps...