Two-electron-state molecule in strong electric fields

The paper deals with the interaction of strong and pulsed radiation fields with a two-electron-state molecule. The light pulses under discussion are shorter than a vibrational period. The molecule is treated within the framework of the Born-Oppenheimer approximation. The nuclear degree of freedom is modeled as displaced harmonic potentials for the ground and the excited electronic states, respectively. Using coherent states as expansion tools for the nuclear motion, analytical expressions are given for the short-pulse region defined by the duration of the light pulse and the displacement of the potentials. The resonance condition is derived for this region. It is shown that within the short-pulse region the two-electron-state molecule mimics the behavior of a two-electron-state atom. Longer pulses are treated with numerical methods. The concept of resonance is discussed for the longer-pulse case. Limitations on population inversion are considered.