Dynamics of high molecular Rydberg states in the presence of a weak dc field

It is argued that under the conditions of current experimental interest, one role of a weak electrical dc field on the dynamics of a high Rydberg molecular electron is to stretch the time axis. The stretch factor is essentially independent of the field and provides a classical analog of the quantum mechanical 'dilution' effect. A second role of the field is to lower the threshold for ionization thereby reducing the energetic requirements for auto-ionization. It is argued that the implications of the presence of the field are quite different for lower Rydberg states. Classical trajectory computations using action-angle variables are used to validate the proposed interpretation and to probe the nature of the possible intramolecular decay channels.