Photoassociation of 5 s n d 1 D 2 − 5 s 2 1 S 0 ultralong-range Rydberg dimers from an ultracold Sr 84 atomic gas in a magnetic field is studied. In the absence of magnetic fields, the electronic wave function is aligned along the rotating molecular axis through electron-atom scattering. With increasing magnetic field strength, the symmetry axis of the electron wave function becomes determined by the applied field. While the ground-state atom has no spin or net charge to interact directly with the magnetic field, the dimer wave function in the limit of strong magnetic field becomes aligned along the applied field. Photoassociation spectra show that with increasing field, an increasing number of rovibrational states are excited, indicating strong coupling between rotational states within the Rydberg dimer.
Wave functions, energies, and binding energies for the lowest singlet states of ${\mathrm{H}}^{\ensuremath{-}}$ and He in uniform magnetic fields
B<109 G are calculated using an adiabatic approximation in hyperspherical coordinates. In computing the angular part of the wave functions, a coupled expansion in one-electron oblate spheroidal angle functions is used. In addition to contracting the two-electron wave function radially, the magnetic field is found to distort the angular part of the wave function mainly by reducing the
ss1S character of the state and replacing it with an
sd1D character. Results for energies and binding energies are comparable with those obtained in variational calculations. In order to compute the binding energies of ${\mathrm{H}}^{\ensuremath{-}}$ and He we have also calculated the binding energies of the ground states of H and
He+ in uniform magnetic fields
B<109 G using the adiabatic oblate-spheroidal-coordinate method of Starace and Webster.