Competing Deactivation Channels for Excited π-Stacked Cytosines
The deactivation of π-stacked cytosine molecules following excitation by ultrashort laser pulses was studied using semiclassical dynamics simulations. Another deactivation channel was found to compete with a previously reported path that led to dimerization. For both pathways, the initial excited s...
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| Format: | Article |
| Language: | English |
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Wiley
2014-01-01
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| Series: | International Journal of Photoenergy |
| Online Access: | http://dx.doi.org/10.1155/2014/158523 |
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| author | Shuai Yuan Huiling Hong Gang Wang Wenying Zhang Yusheng Dou Glenn V. Lo |
| author_facet | Shuai Yuan Huiling Hong Gang Wang Wenying Zhang Yusheng Dou Glenn V. Lo |
| author_sort | Shuai Yuan |
| collection | DOAJ |
| description | The deactivation of π-stacked cytosine molecules following excitation by ultrashort laser pulses was studied using semiclassical dynamics simulations. Another deactivation channel was found to compete with a previously reported path that led to dimerization. For both pathways, the initial excited state was found to form a charge-separated neutral exciton state, which forms an excimer state by charge transfer. When the interbase distance becomes less than 3 Å, charge recombination occurs due to strong intermolecular interaction, ultimately leading to an avoided crossing. Results indicate that the C2–N1–C6–C5 and C2′–N1′–C6′–C5′ dihedral angles play a significant role in the vibronic coupling between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). Vibrational energy distribution determines the fate of the excimer at the avoided crossing. Higher-amplitude vibration of C5 or C6 atoms leads to a nonadiabatic transition to the electronic ground state (a photophysical pathway); otherwise, a chemical reaction leading to the formation of cyclobutane type dimer occurs as found in earlier studies. The S1 and S0 potential energy surfaces calculated at TD-DFT level and the simulated trajectories were found to be consistent with CASPT2 results. |
| format | Article |
| id | doaj-art-69a8e93d9510411284755a3f0b22bc75 |
| institution | Kabale University |
| issn | 1110-662X 1687-529X |
| language | English |
| publishDate | 2014-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | International Journal of Photoenergy |
| spelling | doaj-art-69a8e93d9510411284755a3f0b22bc752025-02-03T01:31:33ZengWileyInternational Journal of Photoenergy1110-662X1687-529X2014-01-01201410.1155/2014/158523158523Competing Deactivation Channels for Excited π-Stacked CytosinesShuai Yuan0Huiling Hong1Gang Wang2Wenying Zhang3Yusheng Dou4Glenn V. Lo5College of Bio-information, Chongqing University of Posts and Telecommunications, Chongqing 400065, ChinaCollege of Bio-information, Chongqing University of Posts and Telecommunications, Chongqing 400065, ChinaCollege of Bio-information, Chongqing University of Posts and Telecommunications, Chongqing 400065, ChinaCollege of Bio-information, Chongqing University of Posts and Telecommunications, Chongqing 400065, ChinaCollege of Bio-information, Chongqing University of Posts and Telecommunications, Chongqing 400065, ChinaDepartment of Physical Sciences, Nicholls State University, P.O. Box 2022, Thibodaux, LA 70310, USAThe deactivation of π-stacked cytosine molecules following excitation by ultrashort laser pulses was studied using semiclassical dynamics simulations. Another deactivation channel was found to compete with a previously reported path that led to dimerization. For both pathways, the initial excited state was found to form a charge-separated neutral exciton state, which forms an excimer state by charge transfer. When the interbase distance becomes less than 3 Å, charge recombination occurs due to strong intermolecular interaction, ultimately leading to an avoided crossing. Results indicate that the C2–N1–C6–C5 and C2′–N1′–C6′–C5′ dihedral angles play a significant role in the vibronic coupling between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). Vibrational energy distribution determines the fate of the excimer at the avoided crossing. Higher-amplitude vibration of C5 or C6 atoms leads to a nonadiabatic transition to the electronic ground state (a photophysical pathway); otherwise, a chemical reaction leading to the formation of cyclobutane type dimer occurs as found in earlier studies. The S1 and S0 potential energy surfaces calculated at TD-DFT level and the simulated trajectories were found to be consistent with CASPT2 results.http://dx.doi.org/10.1155/2014/158523 |
| spellingShingle | Shuai Yuan Huiling Hong Gang Wang Wenying Zhang Yusheng Dou Glenn V. Lo Competing Deactivation Channels for Excited π-Stacked Cytosines International Journal of Photoenergy |
| title | Competing Deactivation Channels for Excited π-Stacked Cytosines |
| title_full | Competing Deactivation Channels for Excited π-Stacked Cytosines |
| title_fullStr | Competing Deactivation Channels for Excited π-Stacked Cytosines |
| title_full_unstemmed | Competing Deactivation Channels for Excited π-Stacked Cytosines |
| title_short | Competing Deactivation Channels for Excited π-Stacked Cytosines |
| title_sort | competing deactivation channels for excited π stacked cytosines |
| url | http://dx.doi.org/10.1155/2014/158523 |
| work_keys_str_mv | AT shuaiyuan competingdeactivationchannelsforexcitedpstackedcytosines AT huilinghong competingdeactivationchannelsforexcitedpstackedcytosines AT gangwang competingdeactivationchannelsforexcitedpstackedcytosines AT wenyingzhang competingdeactivationchannelsforexcitedpstackedcytosines AT yushengdou competingdeactivationchannelsforexcitedpstackedcytosines AT glennvlo competingdeactivationchannelsforexcitedpstackedcytosines |