The Renner-Teller effect in HCCCl{sup +}(X{sup ~2}Π) studied by zero-kinetic energy photoelectron spectroscopy and ab initio calculations
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China)
The spin-vibronic energy levels of the chloroacetylene cation up to 4000 cm{sup −1} above the ground state have been measured using the one-photon zero-kinetic energy photoelectron spectroscopic method. The spin-vibronic energy levels have also been calculated using a diabatic model, in which the potential energy surfaces are expressed by expansions of internal coordinates, and the Hamiltonian matrix equation is solved using a variational method with harmonic basis functions. The calculated spin-vibronic energy levels are in good agreement with the experimental data. The Renner-Teller (RT) parameters describing the vibronic coupling for the H—C≡C bending mode (ε{sub 4}), Cl—C≡C bending mode (ε{sub 5}), the cross-mode vibronic coupling (ε{sub 45}) of the two bending vibrations, and their vibrational frequencies (ω{sub 4} and ω{sub 5}) have also been determined using an effective Hamiltonian matrix treatment. In comparison with the spin-orbit interaction, the RT effect in the H—C≡C bending (ε{sub 4}) mode is strong, while the RT effect in the Cl—C≡C bending mode is weak. There is a strong cross-mode vibronic coupling of the two bending vibrations, which may be due to a vibronic resonance between the two bending vibrations. The spin-orbit energy splitting of the ground state has been determined for the first time and is found to be 209 ± 2 cm{sup −1}.
- OSTI ID:
- 22415798
- Journal Information:
- Journal of Chemical Physics, Vol. 142, Issue 19; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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