Unraveling the relaxation dynamics of Uracil: insights from time-resolved X-ray photoelectron spectroscopy
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arXiv
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| Formato: | Preprint |
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2025
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| author | Faccialà, Davide Bonanomi, Matteo Tenorio, Bruno Nunes Cabral Avaldi, Lorenzo Bolognesi, Paola Callegari, Carlo Coreno, Marcello Coriani, Sonia Decleva, Piero Devetta, Michele Došlić, Nađa De Fanis, Alberto Di Fraia, Michele Lever, Fabiano Mazza, Tommaso Meyer, Michael Mullins, Terry Ovcharenko, Yevheniy Pal, Nitish Piancastelli, Maria Novella Richter, Robert Rivas, Daniel E. Sapunar, Marin Senfftleben, Björn Usenko, Sergey Vozzi, Caterina Gühr, Markus Prince, Kevin C. Plekan, Oksana |
| author_facet | Faccialà, Davide Bonanomi, Matteo Tenorio, Bruno Nunes Cabral Avaldi, Lorenzo Bolognesi, Paola Callegari, Carlo Coreno, Marcello Coriani, Sonia Decleva, Piero Devetta, Michele Došlić, Nađa De Fanis, Alberto Di Fraia, Michele Lever, Fabiano Mazza, Tommaso Meyer, Michael Mullins, Terry Ovcharenko, Yevheniy Pal, Nitish Piancastelli, Maria Novella Richter, Robert Rivas, Daniel E. Sapunar, Marin Senfftleben, Björn Usenko, Sergey Vozzi, Caterina Gühr, Markus Prince, Kevin C. Plekan, Oksana |
| contents | We report a study of the electronic and nuclear relaxation dynamics of the photoexcited RNA base uracil in the gas phase, using time-resolved core level photoelectron spectroscopy together with high level calculations. The dynamics was investigated by trajectory surface-hopping calculations, and the core ionization energies were calculated for geometries sampled from these. The molecule was excited by a UV laser and dynamics was probed on the oxygen, nitrogen and carbon site by core electron spectroscopy. Assuming a particular model, we find that the initially excited $S_2(ππ^*)$ state of uracil decays with a time constant of 17 $\pm$ 4 fs to the ground state directly, or to the $S_1(nπ^*)$ state via internal conversion. We find no evidence that the $S_1(nπ^*)$ state decays to the ground state by internal conversion; instead it decays to triplet states with a time constant of 1.6 $\pm$ 0.4 ps. Oscillations of the $S_1(nπ^*)$ state O 1s intensity as a function of time correlate with those of calculated C4=O8 and C5=C6 bond lengths, which undergo a sudden expansion following the initial $π\to π^*$ excitation. We also observe oscillations in the mean energy of the main line (core ionized ionic state), which we tentatively assign to dynamics of the hot ground state. Our calculations support our interpretation of the data, and provide detailed insight into the relaxation processes of uracil. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_18723 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Unraveling the relaxation dynamics of Uracil: insights from time-resolved X-ray photoelectron spectroscopy Faccialà, Davide Bonanomi, Matteo Tenorio, Bruno Nunes Cabral Avaldi, Lorenzo Bolognesi, Paola Callegari, Carlo Coreno, Marcello Coriani, Sonia Decleva, Piero Devetta, Michele Došlić, Nađa De Fanis, Alberto Di Fraia, Michele Lever, Fabiano Mazza, Tommaso Meyer, Michael Mullins, Terry Ovcharenko, Yevheniy Pal, Nitish Piancastelli, Maria Novella Richter, Robert Rivas, Daniel E. Sapunar, Marin Senfftleben, Björn Usenko, Sergey Vozzi, Caterina Gühr, Markus Prince, Kevin C. Plekan, Oksana Chemical Physics We report a study of the electronic and nuclear relaxation dynamics of the photoexcited RNA base uracil in the gas phase, using time-resolved core level photoelectron spectroscopy together with high level calculations. The dynamics was investigated by trajectory surface-hopping calculations, and the core ionization energies were calculated for geometries sampled from these. The molecule was excited by a UV laser and dynamics was probed on the oxygen, nitrogen and carbon site by core electron spectroscopy. Assuming a particular model, we find that the initially excited $S_2(ππ^*)$ state of uracil decays with a time constant of 17 $\pm$ 4 fs to the ground state directly, or to the $S_1(nπ^*)$ state via internal conversion. We find no evidence that the $S_1(nπ^*)$ state decays to the ground state by internal conversion; instead it decays to triplet states with a time constant of 1.6 $\pm$ 0.4 ps. Oscillations of the $S_1(nπ^*)$ state O 1s intensity as a function of time correlate with those of calculated C4=O8 and C5=C6 bond lengths, which undergo a sudden expansion following the initial $π\to π^*$ excitation. We also observe oscillations in the mean energy of the main line (core ionized ionic state), which we tentatively assign to dynamics of the hot ground state. Our calculations support our interpretation of the data, and provide detailed insight into the relaxation processes of uracil. |
| title | Unraveling the relaxation dynamics of Uracil: insights from time-resolved X-ray photoelectron spectroscopy |
| topic | Chemical Physics |
| url | https://arxiv.org/abs/2503.18723 |