Ultrafast fragmentation dynamics of carbon dioxide trication induced by an intense laser field: Transient deformation route vs direct Coulomb repulsion.

Abstract

We present a combined experimental and theoretical study of the detailed fragmentation process of CO23+→ CO2+ + O+ induced by an intense laser field. Through multicoincidence fragment measurements together with ab initio molecular dynamics (AIMD) simulations, we find that a transient deformation route appears in competition with the expected Coulomb explosion. The AIMD simulations visually demonstrate that CO23+ undergoes several bending vibrations in ∼50-480 fs, and in the final dissociation stages, the electron density distribution in three-dimensional space migrates from the O ion to the C ion, while the bond strength rapidly decreases to 0, resulting in bond breaking assisted by the asymmetric stretching vibrations. The measured kinetic energy releases are in general agreement with AIMD simulations, and the deduced amount of energy transfer into the vibrational and rotational degrees of freedom of CO2+ is about 3 eV less than that estimated by the Coulomb potential.