Imaging transient molecular configurations in UV-excited diiodomethane
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arXiv
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| Main Authors: | , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866915771936931840 |
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| author | Venkatachalam, Anbu Selvam Lam, Huynh Van Sa Bhattacharyya, Surjendu Kaderiya, Balram Wang, Enliang Ding, Yijue Greenman, Loren Rudenko, Artem Rolles, Daniel |
| author_facet | Venkatachalam, Anbu Selvam Lam, Huynh Van Sa Bhattacharyya, Surjendu Kaderiya, Balram Wang, Enliang Ding, Yijue Greenman, Loren Rudenko, Artem Rolles, Daniel |
| contents | Femtosecond structural dynamics of diiodomethane ($\mathrm{CH_2I_2}$) triggered by ultraviolet (UV) photoabsorption at 290 nm and 330 nm are studied using time-resolved coincident Coulomb explosion imaging driven by a near-infrared probe pulse. We map the dominant single-photon process, the cleavage of the carbon-iodine bond producing rotationally excited $\mathrm{CH_2I}$ radical, identify the contributions of the three-body ($\mathrm{CH_2} + \mathrm{I} + \mathrm{I}$) dissociation and molecular iodine formation channels, which are primarily driven by the absorption of more than one UV photon, and demonstrate the existence of a weak reaction pathway involving the formation of short-lived transient species resembling iso-$\mathrm{CH_2I{-}I}$ geometries with a slightly shorter I-I separation compared to the ground-state $\mathrm{CH_2I_2}$. These transient molecular configurations, which can be separated from the other channels by applying a set of conditions on the correlated momenta of three ionic fragments, are formed within approximately 100 fs after the initial photoexcitation and decay within the next 100 fs. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_07289 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Imaging transient molecular configurations in UV-excited diiodomethane Venkatachalam, Anbu Selvam Lam, Huynh Van Sa Bhattacharyya, Surjendu Kaderiya, Balram Wang, Enliang Ding, Yijue Greenman, Loren Rudenko, Artem Rolles, Daniel Chemical Physics Atomic and Molecular Clusters Femtosecond structural dynamics of diiodomethane ($\mathrm{CH_2I_2}$) triggered by ultraviolet (UV) photoabsorption at 290 nm and 330 nm are studied using time-resolved coincident Coulomb explosion imaging driven by a near-infrared probe pulse. We map the dominant single-photon process, the cleavage of the carbon-iodine bond producing rotationally excited $\mathrm{CH_2I}$ radical, identify the contributions of the three-body ($\mathrm{CH_2} + \mathrm{I} + \mathrm{I}$) dissociation and molecular iodine formation channels, which are primarily driven by the absorption of more than one UV photon, and demonstrate the existence of a weak reaction pathway involving the formation of short-lived transient species resembling iso-$\mathrm{CH_2I{-}I}$ geometries with a slightly shorter I-I separation compared to the ground-state $\mathrm{CH_2I_2}$. These transient molecular configurations, which can be separated from the other channels by applying a set of conditions on the correlated momenta of three ionic fragments, are formed within approximately 100 fs after the initial photoexcitation and decay within the next 100 fs. |
| title | Imaging transient molecular configurations in UV-excited diiodomethane |
| topic | Chemical Physics Atomic and Molecular Clusters |
| url | https://arxiv.org/abs/2506.07289 |