Predicting Accurate X-ray Absorption Spectra for CN$^+$, CN, and CN$^-$: Insights from Multiconfigurational and Density Functional Simulations
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| Format: | Preprint |
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2024
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| _version_ | 1866912364281987072 |
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| author | Li, Jinyu Wang, Sheng-Yu Zhang, Lu Ge, Guoyan Wei, Minrui Zuo, Junxiang Hua, Weijie |
| author_facet | Li, Jinyu Wang, Sheng-Yu Zhang, Lu Ge, Guoyan Wei, Minrui Zuo, Junxiang Hua, Weijie |
| contents | High-resolution X-ray spectroscopy is an essential tool in X-ray astronomy, enabling detailed studies of celestial objects and their physical and chemical properties. However, comprehensive mapping of high-resolution X-ray spectra for even simple interstellar and circumstellar molecules is still lacking. In this study, we conducted systematic quantum chemical simulations to predict the C1s X-ray absorption spectra of CN$^+$, CN, and CN$^-$. Our findings provide valuable references for both X-ray astronomy and laboratory studies. We assigned the first electronic peak of CN$^+$ and CN to C1s $\rightarrow σ^*$ transitions, while the peak for CN$^-$ corresponds to a C1s $\rightarrow π^*$ transition. We explained that the two-fold degeneracy ($π^*_{xz}$ and $π^*_{yz}$) of the C1s$\rightarrowπ^*$ transitions results in CN$^-$ exhibiting a significantly stronger first absorption compared to the other two systems. We further calculated the vibronic fine structures for these transitions using the quantum wavepacket method based on multiconfigurational-level, anharmonic potential energy curves, revealing distinct energy positions for the 0-0 absorptions at 280.7 eV, 279.6 eV, and 285.8 eV. Each vibronic profile features a prominent 0-0 peak, showing overall similarity but differing intensity ratios of the 0-0 and 0-1 peaks. Notably, introducing a C1s core hole leads to shortened C-N bond lengths and increased vibrational frequencies across all species. These findings enhance our understanding of the electronic structures and X-ray spectra of carbon-nitrogen species, emphasizing the influence of charge state on X-ray absorptions. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2412_19065 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Predicting Accurate X-ray Absorption Spectra for CN$^+$, CN, and CN$^-$: Insights from Multiconfigurational and Density Functional Simulations Li, Jinyu Wang, Sheng-Yu Zhang, Lu Ge, Guoyan Wei, Minrui Zuo, Junxiang Hua, Weijie Chemical Physics High Energy Astrophysical Phenomena Atomic and Molecular Clusters Computational Physics High-resolution X-ray spectroscopy is an essential tool in X-ray astronomy, enabling detailed studies of celestial objects and their physical and chemical properties. However, comprehensive mapping of high-resolution X-ray spectra for even simple interstellar and circumstellar molecules is still lacking. In this study, we conducted systematic quantum chemical simulations to predict the C1s X-ray absorption spectra of CN$^+$, CN, and CN$^-$. Our findings provide valuable references for both X-ray astronomy and laboratory studies. We assigned the first electronic peak of CN$^+$ and CN to C1s $\rightarrow σ^*$ transitions, while the peak for CN$^-$ corresponds to a C1s $\rightarrow π^*$ transition. We explained that the two-fold degeneracy ($π^*_{xz}$ and $π^*_{yz}$) of the C1s$\rightarrowπ^*$ transitions results in CN$^-$ exhibiting a significantly stronger first absorption compared to the other two systems. We further calculated the vibronic fine structures for these transitions using the quantum wavepacket method based on multiconfigurational-level, anharmonic potential energy curves, revealing distinct energy positions for the 0-0 absorptions at 280.7 eV, 279.6 eV, and 285.8 eV. Each vibronic profile features a prominent 0-0 peak, showing overall similarity but differing intensity ratios of the 0-0 and 0-1 peaks. Notably, introducing a C1s core hole leads to shortened C-N bond lengths and increased vibrational frequencies across all species. These findings enhance our understanding of the electronic structures and X-ray spectra of carbon-nitrogen species, emphasizing the influence of charge state on X-ray absorptions. |
| title | Predicting Accurate X-ray Absorption Spectra for CN$^+$, CN, and CN$^-$: Insights from Multiconfigurational and Density Functional Simulations |
| topic | Chemical Physics High Energy Astrophysical Phenomena Atomic and Molecular Clusters Computational Physics |
| url | https://arxiv.org/abs/2412.19065 |