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

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