A spectroscopic determination of e/m

Abstract

Rydberg constants for hydrogen and helium.—By an interferometer method the wave-lengths of the hydrogen lines at 6563A and 4861A were measured with reference to λ5015.6750 of He as standard. The values so obtained were, for the doublet at 6563A, 6562.7110±.0018 and 6562.8473±.0009; and for the doublet at 4861, 4861.2800±.0013 and 4861.3578±0022. Similarly the wave-lengths of the 4686 lines of ionized helium were found to be 4685.7030±.0012 and 4685.8030±.0026. From these values of the wave-lengths the Rydberg constant for hydrogen, RH is calculated to be 109,677.759±.008, and the Rydberg constant for helium, RHe, to be 109, 722.403±.004. Calculation of e/m.—The ratio of the mass of the electron to the mass of the hydrogen nucleus, m/mH, is given by m/mH=(RHe-RH)(mHe-m)/RH(mHe-mH)=1.33648(RHe-RH)/RH. The value of e/m is given in terms of the Faraday constant as e/m=(mH/m)(F/mH). If the values of RH and RHe calculated above be substituted in these expressions and if it be assumed that F=96470 abamp. per gr. mol. and mH=1.0072, it is found that e/m has the value (1.7606±.0010)×10^(7) e.m.u. per gr.