Thermalisation of C2− with noble gases in cold ion traps

Abstract

The potential energy surfaces for C2− (Σg+2) interacting with He, Ne and Ar are calculated using ab initio quantum chemistry methods. The PES are used to carry out coupled-channel quantum scattering calculations for the three systems to obtain the rotationally inelastic scattering cross sections from which the rotationally inelastic state-changing rate coefficients are computed. These rate coefficients are then used to compute thermalisation times of C2− in an ion trap employing He, Ne or Ar as different, and possible, buffer gases. A detailed analysis of their comparative collisional efficiencies is presented for guidance in trap modeling studies.