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| Author(s): |
João Gabriel Farias Romeu
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2023-05-17 |
| Examining board members: |
Fernando Rei Ornellas;
Amaury Augusto de Almeida;
Ataualpa Albert Carmo Braga;
Francisco Bolivar Correto Machado
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| Advisor: | Fernando Rei Ornellas |
| Abstract | |
The main goals of this work were the spectroscopic and the electronic structure characterizations of diatomic dications containing transition metals and the kinetic studies of the charge transfer reactions M2+ + X → M+ + X+, where M is a transition metal atom. The systems studied were ScS2+, VX+,2+ (X = Ar, Kr) and YH2+ (Y = Sc, V, Cr, Mn, Cu), using the SA-CASSCF and icMRCI+Q methodologies, considered as the stateof-the-art in the computational chemistry, and a quintuple-zeta quality basis sets. The Λ + S electronic states associated to the lowest-lying dissociation channels of these ten systems were characterized, obtaining equilibrium internuclear distances (Re), vibrational parameters (ωe, ωexe, ωeye), excitation (Te) and dissociation (De) energies, besides additional properties. Relativistic spin-orbit effects were also included, obtaining the Ω states to evaluate changes in the energetic profiles of the states. Dipole moments and electronic transitions were also analyzed, as well as Einstein spontaneous emission coefficients and the radiative lifetimes were also calculated, quantifying the transition probabilities. The ScS2+, VAr2+ and VKr2+ systems were characterized for the first time in the literature and the results here obtained should guide future experimental and theoretical investigations that could be carried out with these and similar systems. For the other systems, there are only few studies and few theoretical and experimental information available in the literature, some of which were corroborated by this work and improved with the new information and analysis done here. In the case of Var+ and VKr+, our study revealed intermediate electronic states that would hardly be detected experimentally, besides confirming the photoabsorption pattern determined experimentally. In the case of ScH2+, VH2+, CrH2+ and MnH2+, the potential energy curves were also in accordance with those of existing theoretical studies, that focused only on the first bound dissociation channel, while we could describe other electronic states not previously covered. For the CuH2+ system, the energetic profile was obtained for the first time and evidence was found of possible inconsistencies with another theoretical work of this system. The characterization of the diatomic dications of the five monohydrides investigated allowed us to analyze the kinetics of the reactions Y2+ + H → Y+ + H+, which occurrence probabilities turned out to be much larger when the repulsive states crossed the bound states up to 20 a0. Nevertheless, only for the CuH2+ system the cross sections turned out to be high enough for this type of transfer to occur, while, for the others, the probabilities were relatively low. Overall, the high reliability in the methodology used and in the results presented and compared, when it was the case, make of this work an important reference for future theoretical and experimental studies of the spectroscopy and the kinetics involving these challenging compounds. (AU) | |
| FAPESP's process: | 18/14845-6 - Diatomic dications containing transition metals: electronic structure, spectroscopy, thermochemistry, and reactivity |
| Grantee: | João Gabriel Farias Romeu |
| Support Opportunities: | Scholarships in Brazil - Doctorate (Direct) |