2012 BFY Abstract Detail Page
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||W13 - Optical Spectroscopy/Zeeman Effect
||The Zeeman effect offers a striking visual demonstration of a quantum system and provides a detailed, multi-faceted corroboration with the theoretical treatment. How can one see the effect and observe the various experimental dependences and not end up believing in quantum mechanics? At the University of Puget Sound the effect is first introduced at the sophomore level in Modern Physics, and then treated in full mathematical detail in senior level Quantum Mechanics. The seniors spend some time observing and quantifying the effect, as one of a few experiments that complement their theoretical studies. Students have also explored the effect in the advanced lab course, and as independent study and summer research projects.
Following an NSF sponsored workshop on advanced lab curricula in the 1990's, we built an Ebert spectrometer to observe and study the Zeeman effect and the fine structure of hydrogen.1 Our instrument has evolved over the years, and now consists of four elements: (1) a discharge source in the field of a permanent magnet, that illuminates an adjustable width slit, (2) an objective mirror (12" diameter f/8), (3) an Echelle grating on a rotary stage, and (4) a ccd camera detector. Working at high order (~20), the Echelle grating gives a resolving power in excess of 500,000 and a resolution of about .01.
A mercury discharge produces several transitions of interest for observing the Zeeman effect.2 The normal effect is observed for the yellow 1D2 1P1 transition at 5790.65 , yielding three lines. The anomalous effect is observed for the blue 3S1 3P1 at 4358.35 (six lines) for the yellow 3D2 1P1 transition at 5769.59 (nine lines) and the green 3S1 3P2 transition at 5460.74 (nine lines). The splittings and the line polarizations yield a quantitative test of the agreement with the predictions given by the Lande g-factor.
For the workshop I will give a brief tour of the instrument, discuss some of the experimental difficulties in its construction and operation, and demonstrate the effect for the mercury (and other) systems.
1. D. Preston and E. Dietz, The Art of Experimental Physics, Wiley 1991.
2. G. Herzberg, Atomic Spectra and Atomic Structure, Dover, 1944.
Download the Workshop Document
University of Puget Sound