The dipole spectrum and properties of helium

Abstract

Analytical representations of the dipole spectrum of the ground state of helium are derived. From them are calculated the Verdet constant, the mean excitation energies I and I1 characterizing stopping and straggling of a beam of fast particles absorbed in helium and the leading coefficient C(a, b)/R6 of the long-range interaction between atoms a and b a distance R apart. I is 42.0 ev, I1 is 73 ev, C(He, He) is 1.471 A.U. and C(He, H) is 2.830 A.U.