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.