AUTHOR=González-Sánchez Lola , Gómez-Carrasco Susana , Santadaría Alberto M. , Wester Roland , Gianturco Francesco A. 

TITLE=Collisional Quantum Dynamics for MgH− (1Σ+) With He as a Buffer Gas: Ionic State-Changing Reactions in Cold Traps

JOURNAL=Frontiers in Chemistry

VOLUME=Volume 7 - 2019

YEAR=2019

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00064

DOI=10.3389/fchem.2019.00064

ISSN=2296-2646

ABSTRACT=We present in this paper a detailed theoretical and computational analysis of the quantum
4 inelastic dynamics involving the lower rotational levels of the MgH-(X1Sigma+) molecular anion in
5 collision with He atoms which provides the buffer gas in a cold trap. The interaction potential
6 between the molecular partner and the He (1S) gaseous atoms is obtained from accurate
7 quantum chemical calculations at the post-Hartree-Fock level as described in this paper. The
8 spatial features and the interpretation strength of the present potential energy surface (PES)
9 are analysed in detail and in comparison with similar, earlier results involving the MgH+ (1Sigma)
10 cation interacting with He atoms. The quantum, multichannel dynamics is then carried out using
11 the newly obtained PES and the final inelastic rats constants, over the range of temperatures
12 which are expected to be present in a cold ion trap experiment, are obtained to generate the
13 multichannel kinetics of population changes observed for the molecular ion during the collisional
14 cooling process. The rotational populations finally achieved at specific temperatures are linked
15 to state-selective laser photo-detachment experiments to be carried out in our laboratory. All
16 intermediate steps of the quantum modelling are also compared with the behaviour of the
17 corresponding MgH+ cation in the trap and the marked differences which exist between the
18 collisional dynamics of the two systems are discussed and explained. The feasibility of the present
19 anion to be involved in state-selective photo-detachment experiments is fully analysed and
20 suggestions are made for the best performing conditions to be expected during trap experiments.