# The Renner-Teller effect in HCCCl{sup +}(X{sup ~2}Π) studied by zero-kinetic energy photoelectron spectroscopy and ab initio calculations

## Abstract

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 timemore »

- Authors:

- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China)

- Publication Date:

- OSTI Identifier:
- 22415798

- Resource Type:
- Journal Article

- Journal Name:
- Journal of Chemical Physics

- Additional Journal Information:
- Journal Volume: 142; Journal Issue: 19; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BASES; CATIONS; COMPARATIVE EVALUATIONS; GROUND STATES; HAMILTONIANS; KINETIC ENERGY; L-S COUPLING; MATRICES; PHOTOELECTRON SPECTROSCOPY; PHOTONS; POTENTIAL ENERGY; RESONANCE; SPIN; SURFACES; VARIATIONAL METHODS

### Citation Formats

```
Sun, Wei, Dai, Zuyang, Wang, Jia, and Mo, Yuxiang, E-mail: ymo@mail.tsinghua.edu.cn.
```*The Renner-Teller effect in HCCCl{sup +}(X{sup ~2}Π) studied by zero-kinetic energy photoelectron spectroscopy and ab initio calculations*. United States: N. p., 2015.
Web. doi:10.1063/1.4919953.

```
Sun, Wei, Dai, Zuyang, Wang, Jia, & Mo, Yuxiang, E-mail: ymo@mail.tsinghua.edu.cn.
```*The Renner-Teller effect in HCCCl{sup +}(X{sup ~2}Π) studied by zero-kinetic energy photoelectron spectroscopy and ab initio calculations*. United States. doi:10.1063/1.4919953.

```
Sun, Wei, Dai, Zuyang, Wang, Jia, and Mo, Yuxiang, E-mail: ymo@mail.tsinghua.edu.cn. Thu .
"The Renner-Teller effect in HCCCl{sup +}(X{sup ~2}Π) studied by zero-kinetic energy photoelectron spectroscopy and ab initio calculations". United States. doi:10.1063/1.4919953.
```

```
@article{osti_22415798,
```

title = {The Renner-Teller effect in HCCCl{sup +}(X{sup ~2}Π) studied by zero-kinetic energy photoelectron spectroscopy and ab initio calculations},

author = {Sun, Wei and Dai, Zuyang and Wang, Jia and Mo, Yuxiang, E-mail: ymo@mail.tsinghua.edu.cn},

abstractNote = {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}.},

doi = {10.1063/1.4919953},

journal = {Journal of Chemical Physics},

issn = {0021-9606},

number = 19,

volume = 142,

place = {United States},

year = {2015},

month = {5}

}