Major ideas
1. An early success of quantum theory was the precise quantitative prediction of energy states in hydrogen atoms. When higher states are excited in, for example, a gas discharge tube, the resulting emission spectrum reveals several sequences of emission lines at predicted wavelengths: Lyman, Balmer, Paschen, etc. The sequences are remarkably predicted by formulas using combinations of integer quantum numbers, with an overall energy scaling called the Rydberg constant. The Balmer series of lines falls within the visible spectrum.
2. Framing the quantum mechanics problem as a two-body interaction and using center-of-mass coordinates results in a predicted dependence of emission wavelengths on nuclear mass. Thus the emission lines from the different isotopes hydrogen and deuterium can be distinguished by a spectrometer with sufficient resolution.
Major equipment
1. Scanned diffraction-grating monochrometer for selecting transmitted wavelengths with high resolution. The spectrometer is designed to permit adjustment of the widths of entrance and exit slits, with corresponding effects on resolution and transmitted light intensities. The instrument is controlled by computer with automated data collection.
2. Photodetector / amplifier assembly for measuring transmitted light intensities with high sensitivity and moderately rapid dynamic response. OR Explaining the workings of the gas discharge tube that produces the spectrum.
Alternatives:
3. Gas discharge tube for producing the emission spectra.
Data analysis
1.) How (and why) to deal with the index of refraction of air. As the index varies with air conditions from weather and equipment and people in the room, we need to account for the index of refraction. The peaks will subtly shift in wavelength. This needs to be accounted for.
2.) How and why is linear regression it the way it is?
Here is a link to the attached document containing prelab questions.
See the documents below.
Vibrations and Waves by A.P. French
Introduction to Modern Optics by Grant R. Fowles