An experimental determination of the Rydberg constant

Abstract

The wavelengths of components of the Balmer- alpha line in dueterium and tritium have been determined in terms of the ⁸⁶Kr 606 nm primary standard to establish a value for the Rydberg constant. Improved resolution of the fine structure was achieved by using a discharge cooled in liquid helium to reduce the Doppler width. Positions and intensities of the fine structure components were found by analysis of the spectral line profiles. Variation of the discharge conditions produced no effects which could be correlated with predictions of Stark effect theory. The fine structure of tritium was found to be the same as that of deuterium to within experimental error and the isotope shift was satisfactorily described by the reduced mass factor. The value of the Rydberg constant was found to be R_infinity =109 737.326+or-0.008 cm^-1. The estimated error is to be understood as one standard deviation. The result is based on measurements of the three strongest components in the deuterium fine structure.