Inversion of polarization by light-induced stabilization in NO2 revisited

• A novel effect of optical coherence in molecules.
• Optical coherence controls molecular evolution in the excited state.
• The new theory describes the inversion effect and unusual resonances in the total fluorescence intensity.

We show that light-induced coherence between a state |a〉|a〉 of the electronic ground state X2A1X2A1 and a state |b〉|b〉 of the excited electronic state A2B2A2B2 of a laser-induced transition in NO2 affects the evolution of the molecule in the excited state. The optical coherence couples |b〉|b〉 strongly with |a〉|a〉. This optical coupling works against a radiationless process, which is driving the molecule away from the metastable state |b〉|b〉 to a final state |c〉|c〉. The optical field stabilizes the molecule in the state |b〉|b〉 by the coupling to the ground state |a〉|a〉. This causes the inversion effect in NO2.