Bond dissociation energy and electronic spectroscopy of Cr+(NH3) and its isotopomers
| Autor: | Muhammad Affawn Ashraf, Ricardo B. Metz, Justine Kozubal |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Materials science
Analytical chemistry General Physics and Astronomy 02 engineering and technology Configuration interaction 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Electron spectroscopy Bond-dissociation energy 0104 chemical sciences Bond length Excited state Density functional theory Electron configuration Physical and Theoretical Chemistry 0210 nano-technology Ground state |
| Zdroj: | The Journal of Chemical Physics. 149:174301 |
| ISSN: | 1089-7690 0021-9606 |
| DOI: | 10.1063/1.5053691 |
| Popis: | The electronic spectra of Cr+(NH3), Cr+(ND3), and Cr+(15NH3) have been measured from 14 200 to 17 400 cm−1 using photodissociation spectroscopy. Transitions are predominantly observed from the 6A1 ground state, in which the Cr+ has a 3d5 electronic configuration, to the B 6E (Π) state (3d44s). There is extensive vibronic structure in the spectrum due to a long progression in the Cr–N stretch and transitions to all six spin-orbit levels in the upper state. The spin-orbit splitting in the excited state is observed to be Aso′ = 39 cm−1. For the lowest spin-orbit level, the Cr–N stretching frequency in the excited state is 343 cm−1, with an anharmonicity of 4.2 cm−1. The 6E (Π) origin is predicted to lie at T0 = 14 697 cm−1. The first peak observed is due to v′ = 1, so the observed photodissociation onset is thermodynamic rather than spectroscopic, giving D0(Cr+–NH3) = 14 830 ± 100 cm−1 (177.4 ± 1.2 kJ/mol) and D0(Cr+–ND3) = 15 040 ± 30 cm−1 (179.9 ± 0.4 kJ/mol). The 6E (Π) state of Cr+(NH3) is ∼2740 cm−1 less strongly bound than the ground state, and the Cr–N bond length increases by 0.23 ± 0.03 A upon electronic excitation. Calculations at the time-dependent density functional theory (M06) and equations of motion coupled cluster, with single and double excitations (EOM-CCSD) level fairly accurately predict the energy and vibrational frequency of the excited state. Multi-reference configuration interaction calculations show how the spin-orbit states of Cr+(NH3) evolve into those of Cr+ + NH3. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|