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Non-Kasha fluorescence of pyrene emerges from a dynamic equilibrium between excited states
Pyrene fluorescence after a high-energy electronic excitation exhibits a prominent band shoulder not present after excitation at low energies. The standard assignment of this shoulder as a non-Kasha emission from the second-excited state (S2) has been recently questioned. To elucidate this issue, we...
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| Main Authors: | , , , , , , , , |
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| Format: | Default Article |
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2022
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| Online Access: | https://hdl.handle.net/2134/21229346.v1 |
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| _version_ | 1818165719149314048 |
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| author | Gabriel Braun Itamar Borges Jr. Adelia Aquino Hans Lischka Felix Plasser Silmar Andrade do Monte Elizete Ventura Saikat Mukherjee Mario Barbatti |
| author_facet | Gabriel Braun Itamar Borges Jr. Adelia Aquino Hans Lischka Felix Plasser Silmar Andrade do Monte Elizete Ventura Saikat Mukherjee Mario Barbatti |
| author_sort | Gabriel Braun (13880861) |
| collection | Figshare |
| description | Pyrene fluorescence after a high-energy electronic excitation exhibits a prominent band shoulder not present after excitation at low energies. The standard assignment of this shoulder as a non-Kasha emission from the second-excited state (S2) has been recently questioned. To elucidate this issue, we simulated the fluorescence of pyrene using two different theoretical approaches based on the vertical convolution and nonadiabatic dynamics with nuclear ensemble approaches. To conduct the necessary nonadiabatic dynamics simulations with high-lying electronic states and deal with fluorescence timescales of about 100 ns of this large molecule, we developed new computational protocols. The results from both approaches confirm that the band shoulder is, in fact, due to S2 emission. We show that the non-Kasha behavior is a dynamic-equilibrium effect, not caused by a metastable S2 minimum. However, it requires considerable vibrational energy, which can only be achieved in collisionless regimes after transitions into highly excited states. This strict condition explains why the S2 emission was not observed in some experiments. |
| format | Default Article |
| id | rr-article-21229346 |
| institution | Loughborough University |
| publishDate | 2022 |
| record_format | Figshare |
| spelling | rr-article-212293462022-10-19T00:00:00Z Non-Kasha fluorescence of pyrene emerges from a dynamic equilibrium between excited states Gabriel Braun (13880861) Itamar Borges Jr. (13880864) Adelia Aquino (2663293) Hans Lischka (1293861) Felix Plasser (4765107) Silmar Andrade do Monte (13880867) Elizete Ventura (1438489) Saikat Mukherjee (1513819) Mario Barbatti (1294332) Chemical Physics Physical Sciences Chemical Sciences Engineering <p>Pyrene fluorescence after a high-energy electronic excitation exhibits a prominent band shoulder not present after excitation at low energies. The standard assignment of this shoulder as a non-Kasha emission from the second-excited state (S<sub>2</sub>) has been recently questioned. To elucidate this issue, we simulated the fluorescence of pyrene using two different theoretical approaches based on the vertical convolution and nonadiabatic dynamics with nuclear ensemble approaches. To conduct the necessary nonadiabatic dynamics simulations with high-lying electronic states and deal with fluorescence timescales of about 100 ns of this large molecule, we developed new computational protocols. The results from both approaches confirm that the band shoulder is, in fact, due to S<sub>2</sub> emission. We show that the non-Kasha behavior is a dynamic-equilibrium effect, not caused by a metastable S<sub>2</sub> minimum. However, it requires considerable vibrational energy, which can only be achieved in collisionless regimes after transitions into highly excited states. This strict condition explains why the S<sub>2</sub> emission was not observed in some experiments.</p> 2022-10-19T00:00:00Z Text Journal contribution 2134/21229346.v1 https://figshare.com/articles/journal_contribution/Non-Kasha_fluorescence_of_pyrene_emerges_from_a_dynamic_equilibrium_between_excited_states/21229346 CC BY 4.0 |
| spellingShingle | Chemical Physics Physical Sciences Chemical Sciences Engineering Gabriel Braun Itamar Borges Jr. Adelia Aquino Hans Lischka Felix Plasser Silmar Andrade do Monte Elizete Ventura Saikat Mukherjee Mario Barbatti Non-Kasha fluorescence of pyrene emerges from a dynamic equilibrium between excited states |
| title | Non-Kasha fluorescence of pyrene emerges from a dynamic equilibrium between excited states |
| title_full | Non-Kasha fluorescence of pyrene emerges from a dynamic equilibrium between excited states |
| title_fullStr | Non-Kasha fluorescence of pyrene emerges from a dynamic equilibrium between excited states |
| title_full_unstemmed | Non-Kasha fluorescence of pyrene emerges from a dynamic equilibrium between excited states |
| title_short | Non-Kasha fluorescence of pyrene emerges from a dynamic equilibrium between excited states |
| title_sort | non-kasha fluorescence of pyrene emerges from a dynamic equilibrium between excited states |
| topic | Chemical Physics Physical Sciences Chemical Sciences Engineering |
| url | https://hdl.handle.net/2134/21229346.v1 |