Quenching vibrations by collisions in cold traps: A quantum study for MgH+ (X1Σ+) with 4He(1S)

Quantum dynamics of superelastic collisions involving vibrational levels of MgH+ (X-1 Sigma(+)) ions in cold traps, interacting with He-4(S-1) as a buffer gas at relative temperatures down to millikelvins, is discussed using an ab initio computed potential energy surface. The relative efficiency of collisional cooling with respect to collisional quenching of the internal vibrations is examined from the results of the relative sizes of the relevant cross sections in relation to predicting actual behaviour in cold traps. The present study indicates the feasibility of cooling vibrationally 'hot', trapped ions with the buffer gas.