Coherence in polyatomic photodissociation:: Aligned O(3P) from photodissociation of NO2 at 212.8 nm

Strong orbital alignment is observed in the ground-state oxygen atom following photodissociation of NO2 at 212.8 nm using ion imaging. The imaging method allows for investigation of the angular distribution of this alignment, providing insight into the dynamics in the frame of the molecule. The results are analyzed using a rigorous quantum mechanical theory yielding alignment parameters having direct physical significance. This alignment is dominated by a strong incoherent parallel contribution. In addition, the results reveal direct evidence of coherence between parallel and perpendicular contributions to the excitation of a polyatomic molecule, showing that the electron cloud in the recoiling atom "remembers'' the original molecular plane. (C) 1999 American Institute of Physics. [S0021-9606(99)02309-0].