Infrared laser spectroscopy of H sub 2 and D sub 2 Rydberg states. I. Application of the polarization model

Multistate perturbation theory has been used to assign high resolution Rydberg spectra of H{sub 2} and D{sub 2} in the infrared. The theoretical model treats interactions between the H{sup +}{sub 2} ion core and the spatially extended case ({ital d}) Rydberg electron in terms of the multipole moments and polarizabilities of H{sup +}{sub 2}. The long range interaction model of Sturrus, Hessels, Arcuni, and Lundeen (Phys. Rev. A {bold 38}, 135 (1988)) was refined to include terms up to {ital r}{sup {minus}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 {ital r}{sup {minus}4} (low order), {ital r}{sup {minus}6} ( (1)/(2) {ital V}{sub 6}) and {ital r}{sup {minus}8} (high order). The most generally successful model was found to be the (1)/(2) {ital V}{sub 6} vibrationally extended model.