Sodium D lines

The sign of optical rotation is placed in parentheses, (-f) for dextrorotary, (—) for levorotary, and ( ) for racemic, and placed before the formula. The wavelength (in nanometers is indicated by a right subscript unless indicated otherwise, it refers to the sodium D-line. 

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 ... 

What is the energy per photon of the sodium D line ( i = 589 nm) SOLUTION... 

The 3 Pi/2, 3 P2/2 excited states involved in the sodium D lines are the lowest energy excited states of the atom. Consequently, in a discharge in the vapour at a pressure that is sufficiently high for collisional deactivation of excited states to occur readily, a majority of atoms find themselves in these states before emission of radiation has taken place. Therefore... 

Refra.ctlon, Optical glasses are usually described in terms of their refractive index at the sodium D line (589.3 nm), and their v value (or Abbe number) which is a measure of the dispersion or variation of index with wavelength, ie, v = ), in which is the refractive index at the... 

Intense sodium D-line emission results from excited sodium atoms produced in a highly exothermic step (175). Many gas-phase reactions of the alkafl metals are chemiluminescent, in part because their low ioni2ation potentials favor electron transfer to produce intermediate charge-transfer complexes such as [Ck Na 2] (1 )- There appears to be an analogy with solution-phase electron-transfer chemiluminescence in such reactions. 

Refractive index, where given for a uniaxial crystal, is for the ordinary (co) ray where given for a biaxial crystal, the index given is for the median ((3) value. Unless otherwise specified, the index is given for the sodium D-line (X = 589.3 m i). 

Table 6.3 Refractions of some electron groups (measured by sodium D line)...

The situation is perhaps not quite so bad as is implied here, since single measurements of a, are usually made at the sodium D line, 589.6 nm. Nevertheless, it is clearly better to state the wavelength than to assume that this will be understood. 

To express optical rotations in a meaningful way so that comparisons can be made, we have to choose standard conditions. The specific rotation, [a ]D, of a compound is defined as the observed rotation when light of 589.6 nanometer (nm 1 nm = 10-9 m) wavelength is used with a sample pathlength / of 1 decimeter (dm 1 dm = 10 cm) and a sample concentration C of 1 g/mL. (Light of 589.6 nm, the so-called sodium d line, is the yellow light emitted from common sodium lamps.)... 

The experimental values are for the sodium D-lines, but are only slightly changed on extrapolation to infinite wave-length. 

Fajans and Wulff, not yet published. Their ionic refraction values for light of infinite wave-length are found by the methods applied by Fajans and Joos to the refraction for the sodium D-lines. 

Taylor and Jarman [1] observed SL spectra in the range of 280-740 nm from 2 M NaCl solutions saturated with argon, krypton and xenon sonicated at frequencies of 16 and 500 kHz. The spectra showed a continuum background with bands at about 310 nm and a peak of sodium D line, which exhibited appreciable asymmetric broadening, as shown in Fig. 13.2. The bands around 310 nm result from the A2L+ — X2n transition of OH radicals. The OH bands are quenched in salt solutions compared with those in water, which suggests the energy transfer reaction... 

Fig. 13.2 MBSL spectra from 2M-NaCl aqueous solution saturated with xenon at frequencies of 16 kHz (a) and 500 kHz (b). The sodium D lines exhibit asymmetric broadening [1] (Reprinted from the CSIRO Publishing. With permission)...

Fig. 15.5 Long-exposure photographs recorded for argon-saturated water (a) and luminol solution (b) and (c) 10 mM sodium dodecyl sulphate (SDS) solution. The emission spectra in (d) are from pure argon-saturated water and 10 mM SDS solution. Note the sodium D line at 589 nm. In this experiment, sonication was performed at 159 kHz...

Fig. 3.2. Portion of the solar spectrum in the neighbourhood of the sodium D-lines. Adapted from Delbouille, Roland and Neven (1973). 

The refractive index is usually reported as n, where the tiny 25 is the temperature at which the measurement was taken, and the tiny capital D means we ve used light from a sodium lamp, specifically a single yellow frequency called the sodium D line. Fortunately, you don t have to use a sodium lamp if you have an Abbe refractometer. 

Since the degree of rotation depends on the wave length, monochromatic light (light of a single wave length) is necessary and the common polarimeters use the sodium D line (5890°) or the... 

The superscript 20 in the refractive index indicates the temperature at which the measurement was made. The subscript D indicates that the sodium D line (wavelength = 589 nm) was used. 

Polanyi and coworkers (1980-83) monitored the wings to the sodium D-line emission in the reaction... 

The specific optical rotation of a solid substance is usually determined by measuring the angle of rotation at the wavelength of the sodium D-line at a temperature of 20°C, and calculating the result with reference to a layer 1 dm thick of a solution containing 1 g of the substance per ml. It is pertinent to mention here that the specific optical rotation of a solid is always expressed to a given solvent and concentration. 

A general approach for the determination of the absolute configuration of a chiral carbon consists of attaching to it a labile chiral unit and a dissymmetric chromophore and measuring the optical rotation at the sodium D line. This has been successfully applied to amino acids401. 

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