The dynamic process of fragmentation of ${\mathrm{CO}}^{q+}$ excited states is investigated using a pump-probe approach. EUV radiation (32–48 eV) generated by high-order harmonics was used to ionize and excite CO molecules and a time-delayed infrared (IR) pulse (800 nm) was used to influence the evolution of the dissociating multichannel wave packet. Two groups of states, separable experimentally by their kinetic-energy release (KER), are populated by the EUV and lead to ${\mathrm{C}}^{+}$-${\mathrm{O}}^{+}$ fragmentation: direct double ionization of the neutral molecule and fragmentation of the cation leading to ${\mathrm{C}}^{+}$-${\mathrm{O}}^{*}$, followed by autoionization of ${\mathrm{O}}^{*}$. The IR pulse was found to modify the KER of the latter group in a delay-dependent way which is explained with a model calculation.

• Received 15 May 2010

DOI:https://doi.org/10.1103/PhysRevA.82.043410