Dissociation Dynamics of Anionic Carbon Dioxide in the Shape Resonant State 2 Π u .

Dissociative electron attachments via the lowest shape resonant state ² Π _u of CO ₂ ^- , e ^- + CO ₂ → O ^- + CO, are investigated with our high-resolution anion velocity map imaging apparatus. The production efficiency curve of O ^- obtained in this work is consistent with those reported previously. The forward-backward asymmetric distribution superimposed on the isotopic background is observed in the time-sliced velocity image of O ^- yield, implying that the dissociation of CO ₂ ^- ( ² Π _u ) proceeds through a combinational motion of bond stretching and bending. Thereby, the coproduct CO is proposed to be in the rovibrational states. The long-standing arguments about the dissociation dynamics of CO ₂ ^- ( ² Π _u ) are settled.