The Continuous Absorption Coefficient of the Helium Atom.
Abstract
In this paper the continuous absorption coefficient of He i beyond the series limits 504.3 A, 2600.7 A, and 3122 A (i.e., transitions from the ground state 1'S and the two metastable states 23S and 2'S to the continuum) are investigated. For the bound states, wave functions derived from the Ritz principle were used, while for the free states Coulomb wave functions with an effective charge of 1 were used. With these wave functions the continuous absorption crosssections have been derived from the matrix elements not only of the dipole moment but also of the momentum and of the acceleration. The agreement of values derived from the momentum and the dipole moment provides a strong confirmation of the results obtained from them. However, the crosssections derived from the acceleration are much smaller. This last circumstance is due to the fact that the main contribution to the matrix elements of the accelera tion come from very near the origin, where an effective charge of 1 is unsuitable. The integratedfvalues for the three continua have also been computed. When these fvalues for the continua are added to the respective sums for the discrete states evaluated by other authors, we find that the fsum rule is ap proximately satisfied. This is an additional check on our calculation
 Publication:

The Astrophysical Journal
 Pub Date:
 November 1948
 DOI:
 10.1086/145074
 Bibcode:
 1948ApJ...108..354H