The asymmetric broadening of the resonance atomic line of helium is explained by the shape of the potential energy curves of the two center systems consisting of two helium atoms. The broadened atomic lines account for some of the unstable electronic levels of the helium molecule (${\mathrm{He}}_2$), which have hitherto not been found.

• Received 12 June 1931

DOI:https://doi.org/10.1103/PhysRev.38.642