Field ionization and forced autoionization of Li2.

Abstract

Bound ${\mathrm{Li}}_{2}$ states of principal quantum number n=12--14 converging to v=2 and 3 levels of the ground state of ${\mathrm{Li}}_{2}$${\mathrm{}}^{+}$ can be ionized by fields of \ensuremath{\sim}200 V/cm, 2 orders of magnitude less than expected for direct field ionization of these levels. The result is shown to be due to forced autoionization. The field depresses the ionization limit of the series converging to the lowest rotational-vibrational ${\mathrm{Li}}_{2}$${\mathrm{}}^{+}$ levels, and the n=12--14 levels in question autoionize to the Stark-induced continuum.