Dissociative recombination of CH$^+$ molecular ion induced by very low energy electrons

TL;DR

This study uses multichannel quantum defect theory to calculate dissociative recombination cross sections and rate coefficients for CH$^+$ ions at very low electron energies, focusing on the dominant $2$ $^2\Pi$ state and comparing results with experimental data.

Contribution

It provides detailed quantum mechanical calculations of dissociative recombination for CH$^+$, emphasizing the low-energy $2$ $^2\Pi$ state contribution, which is novel at these energy scales.

Findings

Calculated cross sections and rate coefficients for CH$^+$ dissociative recombination.

Identified the $2$ $^2\Pi$ state as the main dissociation pathway at low energies.

Results agree with storage-ring experimental measurements.

Abstract

We used the multichannel quantum defect theory to compute cross sections and rate coefficients for the dissociative recombination of CH$^+$ initially in its lowest vibrational level $v_i^+ = 0$ with electrons of incident energy bellow $0.2$ eV. We have focused on the contribution of the $2$ $^2\Pi$ state which is the main dissociative recombination route at low collision energies. The final cross section is obtained by averaging the relevant initial rotational states $(N_i^+ = 0,\dots,10)$ with a $300$ K Boltzmann distribution.The Maxwell isotropic rate coefficients for dissociative recombination are also calculated for different initial rotational states and for electronic temperatures up to a few hundred Kelvins. Our results are compared to storage-ring measurements.