Exploring the electronic states of the hydroxyl dication OH2+: thermodynamic (meta)stability, bound-free emission spectra, and charge transfer processes

Author(s)

de Melo, Gabriel Fernando ^[1] ; Franzreb, Klaus ^[2] ; Ornellas, Fernando R. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Av Prof Lineu Prestes 748, BR-05508000 Sao Paulo, SP - Brazil

^[2] Arizona State Univ, Dept Chem, Tempe, AZ 85287 - USA

• Document type: Journal article
• Source: Physical Chemistry Chemical Physics; v. 23, n. 24, p. 13672-13679, JUN 28 2021.
• Web of Science Citations: 0

Abstract

Accurate potential energy curves were constructed for a manifold of electronic states of the hydroxyl dication using a highly correlated electronic structure approach (SA-CASSCF/MRCI+Q/aug-cc-pV5Z). The existence of a bound (meta)stable ground state and bound low-lying states for OH2+ are ruled out, but do not exclude the possibility of its transient formation and dissociation along the repulsive ground state potential energy curve. Our results do not support the conclusion reported for the observation of OH2+ by electron ionization from ground state OH+. Despite the repulsive character of the low-lying states, thermodynamic stability was indeed verified for the states 2 (4)pi and 3 (4)sigma(-) along with a series of metastable high-lying doublet states. For the (quasi)bound states, we obtained vibrational levels, spectroscopic parameters, and dipole moment functions. Using accurate transition dipole moment functions, we also evaluated bound-free emission transition probabilities and radiative lifetimes. For transitions from v `= 0, our estimates of 92.8 ns ((4)pi) and 9.3 ns ((4)sigma(-)) indicate that the ones obtained by a multichannel theory of predissociating states are too short (2-60 ps). Landau-Zener cross sections averaged over the Maxwellian distribution of relative velocities, and rate coefficients for the reaction O2+ + H -> O+ + H+ were obtained using the potential energy curves of the states (4)pi and (4)sigma(-) associated with the channel O2+ + H and the repulsive ones dissociating into O+ + H+ leading to good results for the rate constant thus supporting its importance to explain the distribution of O+ in astrophysical plasmas. (AU)

• FAPESP's process: 18/06591-4 - Spectroscopic studies of neutral and ionic diatomic systems and of molecular reactions of dications with molecules and atoms in the gas phase
• Grantee: Fernando Rei Ornellas
• Support Opportunities: Regular Research Grants