Fourier transform emission spectra and deperturbation analysis of the A2 Π - X2Σ+ and B2Σ+ - X2Σ+ electronic transitions of ZnH

A discharge-furnace emission source was used to generate the A(2)Pi - X-2 Sigma(+) and B-2 Sigma(+) -> X-2 Sigma(+) spectra of ZnH radical. High resolution emission spectra were recorded with a Fourier transform spectrometer, and several bands have been assigned for the (ZnH)-Zn-64 major isotopologue. The data span the v" = 0-6 levels of the X-2 Sigma(+) ground state, the V = 0-3 levels of the A(2)Pi state, and the v' = 0-2 levels of the B-2 Sigma(+) state, extending to high rotational quantum numbers near and above the dissociation asymptote of the ground state. Large local perturbations were observed in the A(2)Pi and B-2 Sigma(+) electronic states, and a deperturbation analysis was carried out using a single Hamiltonian matrix that includes (2)Pi and (2)Sigma(+) matrix elements, as well as off -diagonal elements coupling vibrational levels of the two electronic states. Band constants and Dunham coefficients were obtained for the A(2)Pi and B-2 Sigma(+) excited states by least-squares-fitting of all the experimental data. The equilibrium vibrational constants omega(e) and omega(e)x(e) have been determined to be 1907.528(4) and 38.674(2) cm(-1), respectively, for the A(2)n state, and 1021.135(94) and 17.725(80) cm(-1), for the B-2 Sigma(+) state, and the equilibrium Zn-H distances (r(e)) are 1.511662(2) A and 2.26805(7) A for the A(2)Pi and B-2 Sigma(+) states, respectively. The RKR potential curves were constructed for the A(2)Pi and B-2 Sigma(+) states, and vibrational radial overlap integrals were computed. The off -diagonal matrix elements coupling the electronic wavefunctions of the A(2)Pi and B-2 Sigma(+) states, i.e., a(+) and b, were determined to be 228 +/- 3 cm(-1) and 0.73 +/- 0.01, respectively, for the ZnH molecule. (C) 2017 Elsevier Inc. All rights reserved.