Efficiency of charge transfer in changing the dissociation dynamics of OD+ transients formed after the photo-fragmentation of D2O

• Published in: The Journal of chemical physics 2023-09, Vol.159 (9)
• Main Authors: Iskandar, W., Rescigno, T. N., Orel, A. E., Severt, T., Larsen, K. A., Streeter, Z. L., Jochim, B., Griffin, B., Call, D., Davis, V., McCurdy, C. W., Lucchese, R. R., Williams, J. B., Ben-Itzhak, I., Slaughter, D. S., Weber, Th
• Format: Article
• Language: English
• Subjects: Channels; Charge efficiency; Charge transfer; Chemical dynamics; Deuteration; Dissociation reaction; Dynamics; First-principle calculations; Fragmentation; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Photodissociation; Photofragment ion imaging; Photofragment spectroscopy; Reaction rate constants; Spin-orbit interactions; Transient states; Transition probabilities
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/5.0159300

We present an investigation of the relaxation dynamics of deuterated water molecules after direct photo-double ionization at 61 eV. We focus on the very rare D+ + O+ + D reaction channel in which the sequential fragmentation mechanisms were found to dominate the dynamics. Aided by theory, the state-selective formation and breakup of the transient OD+(a1Δ, b1Σ+) is traced, and the most likely dissociation path—OD+: a1Δ or b1Σ+ → A 3Π → X 3Σ− → B 3Σ−—involving a combination of spin–orbit and non-adiabatic charge transfer transitions is determined. The multi-step transition probability of this complex transition sequence in the intermediate fragment ion is directly evaluated as a function of the energy of the transient OD+ above its lowest dissociation limit from the measured ratio of the D+ + O+ + D and competing D+ + D+ + O sequential fragmentation channels, which are measured simultaneously. Our coupled-channel time-dependent dynamics calculations reproduce the general trends of these multi-state relative transition rates toward the three-body fragmentation channels.