Regular Article

Theoretical study of MgNa⁺ ionic system: potential energy curve, vibrational levels, dipole moments, radiative lifetimes and laser-cooling analysis^★

¹ Laboratory of Interfaces and Advanced Materials, Faculty of Science, University of Monastir, 5019 Monastir, Tunisia
² Department of Physics, Khalifa University, P.O. Box 127788, Abu Dhabi, UAE
³ Faculty of Science, Beirut Arab University, P.O. Box 11-5020, Riad El Solh, Beirut 1107 2809, Lebanon
⁴ Department of Mathematics and Natural Sciences, School of Arts and Sciences, American University of Ras Al Khaimah, RAK P.O. Box 10021, UAE

^a e-mail: hamid.berriche@aurak.ac.ae

Received: 21 May 2020
Received in final form: 19 August 2020
Accepted: 8 September 2020
Published online: 3 December 2020

Abstract

An extensive ab-initio quantum chemistry study and a discussion of the possible laser cooling and formation of the heteronuclear ionic MgNa⁺ molecule is presented in this paper. Our work is based on the use of non–empirical pseudo-potentials for the Mg²⁺ and Na⁺ cores, large Gaussian basis sets, parametrized l–dependent polarization potentials, and full valence configuration interaction calculations. We present here adiabatic potential energy curves of the ground and 44 low-lying excited electronic states of ^1,3Σ⁺, ^1,3Π, ^1,3Δ symmetries, and their spectroscopic parameters (R_e, D_e, T_e, ω_e, ω_ex_e, and B_e). Furthermore, numerous ionic – neutral avoided crossings, specially between higher adjacent electronic states of ^1,3Σ⁺, ^1,3Π symmetries, are identified and interpreted. The energy separations between these avoided crossings are also calculated. The electric dipole moment curves have been computed for a wide range of inter-nuclear distances. The vibrational energies are obtained by solving the nuclear Schrodinger equation, using the calculated potential energy curves. Thereafter, spontaneous and black-body radiation induced transition rates are calculated to obtain the ground and excited states vibrational level lifetimes. It has been observed that the lifetimes of the ground state vibrational levels are of the order of a second, while those of the excited states, mainly the 2¹Σ⁺ state, have the order of a nanosecond.