The sodium 3s level is significantly lower than the 3p because of greater penetration past the shielding of the 1s electron.īoth levels penetrate enough to be significantly lower than the n=3 hydrogen energy which they would have if the shielding were perfect. It's as pure a sodium doublet spectrum as I get using a sodium lamp! If it weren't for the electric shock hazard posed by the electric pickle, we might suggest them as low-cost sodium light sources! Neutral lines were select-ed as the measurement wavelengths, but ionic lines were measured for Ba and Y because these elements have no measurable neutral lines. 2) Rotate the telescope on either side (R.H.S.) of Principle maxima, the first order maxima will be observed. But I had no idea that it was such pure sodium light! The spectrum of the electric pickle at right was taken by Benoit Minster of Grenoble, France using a Lhires II spectrograph and a digital camera. 1) Keep the Grating on prism table of the spectrometer and observe the Principal Maxima through telescope. Warning! The electric pickle is a serious shock hazard!įrom the color, I had presumed that the light from the pickle was at least partly sodium light from the sodium chloride used in the pickling process. When Ohm's law is used with ordinary carbon resistors, the ratio of voltage to current is constant, but the variation in light output suggests that this is not the case with the electric pickle. The standard explanation is that the electric current excites the sodium ions, producing light similar to that of a sodium lamp.Ĭurrents in ionic solutions are often not linearly proportional to the applied voltage. After the pickling process, there are Na+ and Cl- ions present. A considerable amount of light can be obtained by connecting ordinary household 120 volt AC voltage across a pickle. At right is a sketch of the origin of the sodium doublet.Ī far-fetched example of a non-ohmic resistor is the electric pickle. The illustration at left shows the interference pattern formed by the sodium doublet in a Fabry-Perot interferometer. All other lines are a factor of two or more fainter than that one, so for most practical purposes, all the light from luminous sodium comes from the D-lines. Taking the range from 400-700nm as the nominal visible range, the strongest visible line other than the D-lines is the line at 568.8205 which has an intensity about 0.7% of that of the strongest line. The line at 589.0 has twice the intensity of the line at 589.6 nm. From the energy level diagram it can be seen that these lines are emitted in a transition from the 3p to the 3s levels. The sodium spectrum is dominated by the bright doublet known as the Sodium D-lines at 588.9950 and 589.5924 nanometers. Why do levels vary with orbital quantum number? Hydrogen-Like Atoms:Sodium Sodium Energy Levels Sodium spectrum
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