Dissociative recombination of the CH${}^{+}$ molecular ion at low energy

The reactive collisions of the CH${}^{+}$ molecular ion with electrons is studied in the framework of the multichannel quantum defect theory, taking into account the contribution of the core-excited Rydberg states. In addition to the $X^1{\mathrm{\Sigma }}^{+}$ ground state of the ion, we also consider the contribution to the dynamics of the $a^3\mathrm{\Pi }$ and $A^1\mathrm{\Pi }$ excited states of CH${}^{+}$. Our results - in the case of the dissociative recombination in good agreement with the storage ring measurements - rely on decisive improvements - complete account of the ionisation channels and accurate evaluation of the reaction matrix - of a previously used model.