Ionisation of atoms by collision with excited atoms at low energies

The authors calculate the cross section for ionisation of a ground-state atom in collisions with atoms excited to their resonant state, using the impact parameter method and the decay approximation. Previous theories took the trajectories of the colliding particles to be rectilinear. They calculate the trajectories by using an appropriate interaction potential and calculate the decay probability for each trajectory numerically. They find the bending of the trajectories of the colliding particles to be important at low colliding energies (T<1000 K), especially when the interaction is strong (e.g. in the case Hg(63P1)-Cs). Also, they find the dipole-dipole perturbation interaction approximation to be very poor and they propose a model to overcome its deficiency. They compare their results with previous calculations and the existing experimental data.