Magnetic stabilization of a Rydberg quasimolecule in circular states

Abstract

An exact analytical classical solution for the electronic terms of circular Rydberg states (CRS) in the presence of a magnetic field $B$ is obtained for two-Coulomb-center systems. The classical electronic terms are shown to be significantly affected by the magnetic field. In particular, a sufficiently strong magnetic field is shown to cause the appearance of CRS above the ionization threshold. These CRS are the classical molecular counterparts of the quantal atomic quasi-Landau levels (resonances). Study of the stability of the nuclear motion in this system reveals that the system in CRS is, in the absence of the magnetic field, not really a molecule, but only a quasimolecule with antibonding molecular orbitals. We also find that the magnetic field creates a deep minimum in one of the branches of the effective potential of the relative motion of the nuclei, and thereby stabilizes the nuclear motion. We have therefore shown that a magnetic field can transform the quasimolecule into a real, classically described molecule where one of the molecular orbitals becomes bonding. This result reveals a phenomenon---the magnetically controlled stabilization of the quasimolecules in CRS---which is appropriate for future experimental studies.