Sodium atomic spectra

In 1817, Josef Fraunhofer (1787-1826) studied the spectrum of solar radiation, observing a continuous spectrum with numerous dark lines. Fraunhofer labeled the most prominent of the dark lines with letters. In 1859, Gustav Kirchhoff (1824-1887) showed that the D line in the solar spectrum was due to the absorption of solar radiation by sodium atoms. The wavelength of the sodium D line is 589 nm. What are the frequency and the wavenumber for this line ... 

However, in the sodium atom, An = 0 is also allowed. Thus the 3s —> 3p transition is allowed, although the 3s —> 4s is forbidden, since in this case A/ = 0 and is forbidden. Taken together, the Bohr model of quantized electron orbitals, the selection rules, and the relationship between wavelength and energy derived from particle-wave duality are sufficient to explain the major features of the emission spectra of all elements. For the heavier elements in the periodic table, the absorption and emission spectra can be extremely complicated - manganese and iron, for example, have about 4600 lines in the visible and UV region of the spectrum. 

We cited sodium previously. Gaseous sodium atoms absorb in the visible region of the spectrum. The few very specific wavelengths for sodium are 589.0 and 589.6 nm.Both of these represent transitions from the 3s level to the 3p level. The 3p level is actually split narrowly into two levels due to the effect of two possible spin states for the electron in this level, hence the observation of two transitions that... 

Spectroscopy is the study of the absorption and emission of radiation by matter. The most easily appreciated aspect of the absorption of radiation is the colour shown by substances that absorb radiation from the visible region of the spectrum. If radiation is absorbed from the red region of the spectrum, the transmitted or unabsorbed radiation will be from the blue region and the substance will show a blue colour. Similarly substances that emit radiation show a particular colour if the radiation is in the visible region of the spectrum. Sodium lamps, for instance, owe their characteristic orange-yellow light to the specific emission of sodium atoms at a wavelength of 589 nm. 

Yellow flame color is achieved by atomic emission from sodium. The emission intensity at 589 nanometers increases as the reaction temperature is raised there is no molecular emitting species here to decompose. Ionization of sodium atoms to sodium ions will occur at very high temperatures, however, so even here there is an upper limit of temperature that must be avoided for maximum color quality. The emission spectrum of a yellow flare is shown in Figure 7.2. 

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

A Procedure to Obtain the Effective Nuclear Charge from the Atomic Spectrum of Sodium 155... 

In the same way, the sodium atoms can be promoted to the doublet levels 3 2Py2 or 3 2Ptii which are split due to spin-orbit coupling. When such atoms return to the ground state, the two closely spaced lines are observed in the emission spectrum. These are the well known D lines of sodium (Figure 2.5). 

FIGURE 5.6 (a) The visible line spectrum of energetically excited sodium atoms consists of a closely spaced pair of yellow lines, (b) The visible line spectrum of excited hydrogen atoms consists of four lines, from indigo at 410 nm to red at 656 nm. 

The most intense (yellow) line in the spectrum of sodium atoms has a wavelength of 589.0 nm. Calculate (a) the corresponding wavenumber, and the transition energy involved, in (b) electron volts per photon, and (c) kilojoules per mol-1. 

Figure 7.7 (a) A simple doublet and (b) a compound doublet in the spectrum of, for example, the sodium atom... 

We have prepared the acetyl radical by the reaction between sodium atoms and acetyl chloride and trapped it in a matrix of water, benzene, benzene-dg, or cyclohexane (Bennett et al., 1969a). The spectrum of the acetyl radical is basically the same in all of the matrices and that in benzene is shown in Fig. 9. The spectrum shows that the orbital of the unpaired electron has approximately axial symmetry, and the principal values of the gr-tensors and hyperfine tensors are ... 

The reaction of sodium atoms with allyl alcohol is also somewhat unusual since the e.s.r. spectrum of the deposit showed that trapped electrons were not present and that the allyl radical was formed exclusively even at 77°K. Thus if electrons were trapped initially the trap must have decomposed rapidly to form the allyl radical and a hydroxyl ion. Such a reaction might occur in this case because of the much weaker CO-bond in the allyl alcohol. Alternatively the alkali metal atom might have reacted directly with the alcohol, the hydroxyl group behaving like a pseudo-halogen group. 

The infrared spectrum of CO2 radical ion (prepared by depositing sodium atoms on solid carbon dioxide) has been obtained and has bands... 

The sodium D-line is actually a pair of closely spaced spectroscopic lines seen in the emission spectrum of sodium atoms. The wavelengths are centered at 589.3 nm. The intensity of this emission makes it the major source of light (and causes the yellow color) in the sodium arc light. 

The ubiquitous nature of the sodium cation often leads to Na cationiza-tion and the presence of [M + Na]+ in the mass spectrum in addition to, or in place of, [M + H]" ". Efforts to either remove or add Na+ from the sample result in changes in the relative abundances of the [M + H]+ and [M+ Na]" ". Addition will often cause replacement of other labile protons with additional sodium atoms. Addition of lithium or potassium can replace the Na+, with the appropriate mass changes, to conhrm the identity of the Na" " adducts. Ammonium cationization will often occur from LC-MS mobile phases containing an ammonium buffer salt. Acetonitrile solvent adducts will also often form. 

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