Grotrian diagrams

The Grotrian diagram in Figure 7.9 gives the energy levels for all the terms arising from the promotion of one electron in helium to an excited orbital. 

Figure 7.9 Grotrian diagram for helium. The scale is too small to show splittings due to spin-orbit coupling...

S. Bashkin and J.O. Stoner, Atomic Energy Levels and Grotrian Diagrams. North-Holland, Amsterdam, 1975. 

Figure 6.4. Grotrian diagram for the sodium atom, showing the energies of the atomic orbitals.

From the Grotrian diagram of an element, the absorption wavelengths of the atoms of that element can be deduced. Theoretically, any transitions between two states permitted by quantum theory can be used in AAS. In practice, however, it is found that this is not the case because the number of atoms in the upper excited state is extremely small and the degree of absorption by these few excited atoms is scarcely measurable. Consequently, absorption lines relating to transitions between an excited state and a higher excited state are insensitive and not analytically useful. 

Figure 2 A partial Grotrian diagram for the element sodium illustrating the observed atomic absorptions as sohd arrows.

MOO/MER] Moore, C. E., Merrill, P. W., Partial Grotrian diagrams of astrophysical interest, Natl. Stand. Ref. Data Ser. (U.S., Natl. Bur. Stand.), 23, (1968). Cited on page 76. 

AAS is useful for the analysis of approximately 70 elements, almost all of them metal or metalloid elements. Grotrian diagrams correctly predict that the energy required to reach even the first excited state of nonmetals is so great that they cannot be excited by normal UV radiation (> 190 nm). The resonance hnes of nonmetals lie in the vacuum UV region. Commercial AAS systems generally have air in the optical path, and the most common atomizer, the flame, must operate in air. Consequently, using flame atomizers, atomic absorption cannot be used for the direct determination of nonmetals. However, nonmetals have been determined by indirect methods, as will be discussed in the applications section. 

Fig. 12.1 E nergy level (Grotrian) diagrams for (a) atomic sodium and (b) magnesium (I) ion.

Figure 1 Partial Grotrian diagram for sodium. (Reprinted from Robinson JW (1990) Atomic Absorption Spectroscopy by courtesy of Marcel Dekker Inc.)...

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