Measurement of the Balmer lines of atomic hydrogen and the fine structure of sodium lines; determination of the mass of the deuteron from the isotope shift. A high resolution monochromator with a wavelength range from 2500 to 15,000 angstroms in first and second order is used to study the Balmer lines of hydrogen and the more complex hydrogenic spectrum of sodium, using the mercury spectrum as the wavelength calibrator.
The measured Balmer wavelengths are compared with the quantum theory of the hydrogen spectrum, and a value of the Rydberg is derived. The transitions responsible for the sodium spectrum are identified, and the regularities in the fine structure and adherence to the selection rules are observed. A research grade monochromator is used to measure the isotope shift between the Balmer lines of hydrogen and deuterium, and the ratio of the deuteron mass to the proton mass is derived from the data.
Lab Guide (PDF)
A high resolution monochromator. (Image courtesy of Junior Lab staff.)
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Hyperphysics Tutorial on Broadening of Spectral Lines