In this experiment, the Rydberg constants for the hydrogen atom and He+ were determined by analysis of the emission spectra of Hand He, respectively, in comparison to the principal quantum numbers of each transition. Using both a hydrogen and then a helium atomic lamp attached to a 0.5 m grating spectrometer and a photomultiplier detector (PMT), a change in voltage detected by the PMT can be paired with a corresponding wavelength passing through the spectrometer from each emission peak in the visible to ultraviolet range. The peaks acquired from this change in voltage were analyzed to find their corresponding wavenumber value and then plotted versus the inverse square of the excited state quantum number (n2). The regression of this plot yields a linear relation that can then be used to calculate the Rydberg constant for H and He+. The values for H were determined to be 109 600 ± 300 cm-1 from the slope value and 109 640 ± 50 cm-1 from the y-intercept when the final state after radiative transition, n1= 2. The values derived from the He II spectrum for He+ were determined to be 111 000 ± 3000 cm-1 from the slope value, and 109 800 ± 700 cm-1 from the y-intercept value when the final state after radiative transition had an n1= 4.
Shaffer, Kyle D.
"Determination of the Rydberg Constant from the Emission Spectra of H and He+,"
Ramifications: Vol. 2
, Article 5.
Available at: https://digitalcommons.wcupa.edu/ramifications/vol2/iss1/5