Infrared laser spectroscopy of H2 and D2 Rydberg states. I. Application of the polarization model

Multistate perturbation theory has been used to assign high resolution Rydberg spectra of H2 and D2 in the infrared. The theoretical model treats interactions between the H+2 ion core and the spatially extended case (d) Rydberg electron in terms of the multipole moments and polarizabilities of H+2. The long range interaction model of Sturrus, Hessels, Arcuni, and Lundeen [Phys. Rev. A 38, 135 (1988)] was refined to include terms up to r−8 in the Rydberg electron radial matrix element. Implementation of the multipole moment–polarization matrix diagonalization model was carried out at three levels: Rotation only (‘‘pure precession’’), vibrationally extended, and full multichannel. At each level the calculations were made to order r−4 (low order), r−6 ( (1)/(2) V6) and r−8 (high order). The most generally successful model was found to be the (1)/(2) V6 vibrationally extended model.