Atomic-beam measurements of heliumF−G,F−H, andF−Iintervals

Abstract

The fast-atomic-beam microwave-optical resonance technique has been used to measure the $8F-8G$, $8F-8H$, $7F-7H$, and $7F-7I$ intervals in helium. The electrostatic fine-structure intervals derived from these measurements and from theoretical values of the magnetic fine structure are $8F-8G$, 3898.525(0.041); $8G-8H$, 931.34(0.44); $7G-7H$, 1359.16(0.11); and $7H-7I$, 402.8(4.7) MHz. Additional theoretical work is needed to understand these intervals beyond the 1% level.