Rotational analysis and deperturbation of the A2Π → X2Σ+ and B′2Σ+ → X2Σ+ emission spectra of MgD

Abstract

High resolution Fourier transform emission spectra of MgD radical were analyzed, and the A2Π → X2Σ+ bands with v′ = 2 and v′ = 3 were rotationally assigned. Several local perturbations were observed in the A2Π and B′2Σ+ excited states of 24MgD, and a deperturbation analysis was carried out using an appropriate Hamiltonian matrix containing off-diagonal terms connecting the vibrational levels of the two states. Dunham coefficients and band constants were determined for the A2Π and B′2Σ+ states, along with off-diagonal parameters. The equilibrium vibrational constants ωe and ωexe have been determined to be 1155.040(6) and 16.764(4) cm−1, respectively, for the A2Π state, and 598.108(11) and 6.394(8) cm−1, for the B′2Σ+ state. The equilibrium Mg–D distances were found to be 1.67819(3) Å and 2.59355(2) Å for the A2Π and B′2Σ+ states, respectively. RKR potential curves were constructed for the A2Π and B′2Σ+ states, and vibrational radial overlap integrals were computed for the perturbed levels. The off-diagonal matrix elements coupling the electronic wavefunctions of the A2Π and B′2Σ+ states were determined independently for MgD to be a+ = 18.9 ± 0.2 cm−1 and b = 0.694 ± 0.005, in excellent agreement with those for the MgH isotopologue.