Field-induced ion-pair formation in molecular hydrogen

Abstract

We present the first experimental results on the electric-field dependence of the threshold for ion-pair formation in a molecular system. The results were obtained for the process ${\mathrm{H}}_{2}$+h\ensuremath{\nu}\ensuremath{\rightarrow}${\mathrm{H}}^{+}$+${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ by using a double-resonance excitation scheme via the E, $^{1}\mathrm{\ensuremath{\Sigma}}_{\mathrm{g}}^{+}$, v=6 level. The similarity of the long-range interaction in the ion-pair system with that of the electron-ion system leads to analogies between the field-induced process and the processes of field ionization and forced autoionization of Rydberg states of atoms.