Sodium electronic transitions

Figure 12.7 Electronic transitions giving rise to the emission spectrum of sodium in the visible, as listed in Table 12.1. The principal series consists of transitions from the 3s level to 3p or a higher p orbital the sharp series from 3p to 4s or a higher s orbital diffuse from 3p to 3d or above and the fundamental from 3d to 4/or higher. The terms below the lines [(R/(3-1.37)2, etc.] are the quantum defect corrections referred to in Section 10.4.

Electronic transitions within a sodium atom giving rise to the main bands in its emission spectrum. 

Figure 1.4 Diagram of energy levels and electronic transitions for atomic sodium.

Iqbal et al. [72,73] have reviewed the physical properties and decompositions of selected inorganic fulminates. The sodium, potassium and thallium salts are predominantly ionic, whereas those of Hg and, possibly, Ag are covalent. Electronic transitions are believed [72] to play an important role in the effects of... 

Both atomic and molecular emission and absoiption can be measured when a sample is atomized in a flame. A typical flame-emission spectrum was shown in Figure 24-19. Atomic emissions in this spectrum are made up of narrow lines, such as that for sodium at about 330 nm, potassium at approximately 404 nm, and calcium at 423 nm. Atomic spectra are thus called line spectra. Also present are emission bands that result from excitation of molecular species such as MgOH, MgO, CaOH, and OH. Here, vibrational transitions superimposed on electronic transitions produce... 

The calculation of such (many-electron) transition probabilities is by no means trivial. It has been done in a statistical approach [15] similar to the one used for multiple ionization of sodium clusters [39]. 

When sodium vapour reacts with stannic chloride, bromide or iodide [89], a continuous chemOuminescence, which is emitted during the primary reaction, occurs. It was pointed out that neither Class I nor Class II mechanisms were applicable. The explanation suggested [55, 89] is the formation of SnCls radicals followed by a luminescent disproportionation reaction, the luminescence being associated with an electronic transition from the Sn" CI2 passing to the stable Sn Cl2 state... 

Atoms as well as molecules have electronic transitions that are not of the Rydberg type. For atoms the famous D-lines of sodium (3s,3p) are an example. For molecules all the familiar (vr, n ) and (n, rr ) transitions of olefins and aromatic molecules are examples of non-Rydberg, valence-shell (or intravalency) type transitions. For typical valence-shell transitions the orbital of the excited electron is not much larger than the molecular core. Bands due to such transitions cannot be ordered into series. The orbital of the excited electron is usually antibonding in one or more bonds wliile Rydberg orbitals because of their large size are, in most cases, essentially non-bonding. 

Table 7. Calculated three lowest-energy electronic transitions in the radical ions 75—81 and the experimental excitation energies observed directly after y-irradiation 5 ) (y) or sodium reduction 8) (Na red.) and inferred from the photo-electron spectra (PES)...

The application of pump-probe spectroscopy to electronic transitions of larger aggregates reveals the rapidly growing number of different dissociation channels. The result of two-color pump-probe femtosecond experiments performed on sodium clusters Na with 3 n 10 is shown in Fig. 8. For At > 0, the energy pump was 1.47 eV, whereas Sprobe> the energy of the... 

If a continuum is used as a radiant energy source and is passed through an atomic vapor, such as sodium, the spectrum obtained will have narrow absorption lines corresponding to several of the easily excited states of sodium. The absorption lines will be very sharp, indicating that only the energy corresponding to the particular electronic transition involved is absorbed. Two important interrelated considerations result from these observations (1) The best emission source for atomic absorption measurements is a spectral line of the same wavelength as the analyte element and... 

The vapor of certain chemical elements imparts a characteristic color to the flame of burning gas (e.g., Bunsen burner). This property is used for identifying quahtatively various metallic elements. The flame coloration is caused by electronic transitions occurring between the energy levels of the atoms of the chemical element. For a particular chemical element the flame coloration is always the same, regardless of whether the chemical element is in the free atomic state or chemically in molecules. For example, free sodium metal, sodium chloride, sodium carbonate and sodium sulfate all impart an intense yellow color to the flame (D-line of 589 nm). This yellow color is characteristic of sodium in any form, and hence can be used as a test for sodium. In the making of flame tests, chlorides of the metals are commonly used, since chlorides are more volatile than other salts. 

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