Precision Wavelength and Isotopic Shift Measurements of Germanium Arc Lines

The employment of an atomic beam light source and of interferometric equipment made it possible to obtain information about the line structure and precision wavelength of eight Ge I lines arising from transitions between the lowest even and odd energy levels of germanium. Despite the high resolving power employed, it was impossible to observe line splittings. By comparing the total width of the lines with that expected from the beam data one can estimate that the isotope shift between consecutive even Ge isotopes is smaller than 0.005 ${\mathrm{cm}}^{-1\mathrm{}}$. The wavelength of the center of gravity of the different lines however, could be determined within ±0.00004 A. This limit of error is in agreement with the wave number deviations obtained by the application of the Ritz combination principle.