Electric-field-induced resonances of highly excited molecules

Abstract

In an electric field of 0\char21{}6.67 kV/cm, nitric oxide (NO) molecules are excited by the double-resonance technique through the intermediate $A{\text{ }}^{2}{\ensuremath{\Sigma}}^{+}{\text{F}}_{1}(v=0,N=0)$ level to the high Rydberg electronic states converging to the ionic ${\text{NO}}^{+}X{\text{ }}^{1}{\ensuremath{\Sigma}}^{+}({v}^{+}=0,{N}^{+}=0)$ level, in the energy region from the classical field-ionization limit ${E}_{C}^{(0,0)}$ to above the zero-field-ionization limit ${E}_{0}^{(0,0)}$. Just below ${E}_{0}^{(0,0)}$, resonances showing Fano profiles through the field-induced autoionization are observed. Above ${E}_{0}^{(0,0)}$, resonances corresponding to the transient states of electrons trapped on the ``uphill'' side of the potential energy raised by the field are observed. These field-induced resonances of molecules from the negative energy region just below the zero-field-ionization limit ${E}_{0}^{(0,0)}$ to the positive energy region are assigned completely. Decoupling of the orbital angular momentum of the Rydberg electron from the core rotation is confirmed in a high electric field.