Fine Structure of the Hydrogen Atom. V

Improvements in apparatus and techniques of measurement of the 2²S₁₂-2²P₁₂ level shifts in hydrogen and deuterium are described. The more accurate results are S_H=1057.77+/-0.10 Mc/sec and S_D=1059.00+/-0.10 Mc/sec. These values are compared with results of quantum electrodynamic calculations. The shape of the resonance curves has been examined in great detail and compared with theory. Assuming the theoretical value of the radiative width and hyperfine splittings, excellent agreement is obtained. Further, if only the radiative width is assumed, measurements on hydrogen reported here confirm theoretical hyperfine splittings to within 0.28 Mc/sec. Since contributions of the hyperfine structure of the 2S level have been measured to far greater accuracy, these results constitute a confirmation of the 2P hyperfine splittings to an accuracy of 1.0 percent.