The fine structure of the α -line of heavy hydrogen

Abstract

In continuation of work reported earlier (Kuhn & Series 1950), the weak satellite 2 P 1/2 –3 S 1/2 in the α-line 6561 Å of the Balmer series of heavy hydrogen has been resolved. The light was produced as before in a U-tube cooled by liquid hydrogen, and analyzed by a double Fabry-Perot interferometer with spacings in the ratio 1:2. The satellite was found to be at a distance 0·1326±0·001 cm. -1 from the neighbouring strong component 2 P /2 –3 D 1/2 , in disagreement with the distance 0·1409 cm. -1 predicted by the Dirac relativistic theory of the hydrogen atom. The difference 0-0083 + 0·002 –0·003 cm. ‒1 (where the limits also include possible errors in certain corrections) is interpreted as an upward shift of the 3 S term, and is compared with the value 0·0104 cm. –1 predicted by the radiation theory of Bethe and others (see, for example, Bethe, Brown & Stehn 1950).