Dispersive systems for atomic spectrometry

Many elemental analysis methods are based on the use of atomic line spectra. These include atomic emission spectrometry, with flame, arc, spark, glow discharge and plasmas (especially inductively coupled plasmas or ICP) as possible radiation sources, atomic absorption spectrometry, with flame and furnace as atomization sources, and atomic fluorescence spectrometry. To be able to use a line in a spectrum, it needs to be isolated using a system that scatters light as a function of wavelength. While the last two types of spectrometry are almost completely free of spectral interference, this is not the case for emission spectrometry. In this case, the line selected for analysis must be separated from the other lines present in the emission spectrum. The role of the dispersive system then becomes crucial, particularly in terms of the versatility of the line selection according to the analytical problem, the resolution required to separate the line and the wavelength range accessible by the system. The different types of spectrometer, diffraction gratings (plane, concave, ladder) and their properties, the different optical set-ups, theoretical and practical resolution concepts, and the measurement of the net intensity of a spectral line are described in this article.