Interpretation of the Stark effect of H- resonances

Resonances in the photodetachment cross sections of H- in a strong dc electric field are studied theoretically in hyperspherical coordinates in the adiabatic approximation. In terms of the variation of one-dimensional effective potentials with electric field for different channels, the experimental results of Gram et al. [Phys. Rev. Lett. 40, 107 (1978)] are interpreted. In particular, the linear Stark splitting of the Feshbach resonance at low fields and the stability of the shape resonance against electric fields up to a few thousand kV/cm are understood from their associated effective potential curves. A new mechanism of field ionization for the ''blue-shifted'' Stark states is also discussed