Decoding the state distribution in a nonadiabatic rotational excitation by a nonresonant intense laser field

We investigated the quantum-state distribution in nonadiabatic rotational excitation induced by a nonresonant intense laser field. NO molecules, initially prepared in the lowest $J=0.5$ state, were rotationally excited to states with up to $J=8.5$ at a laser intensity of 2.5×10¹³0.3em0exW∕cm². The characteristics in the observed state distribution were quantitatively reproduced by a quantum dynamical calculation, and excitation pathways typical to molecules in a doubly degenerate state were identified.