Triplet Mediated C−N Dissociation versus Internal Conversion in Electronically Excited N‑Methylpyrrole
The photochemical and photophysical pathways operative in N-methylpyrrole, after excitation in the near part of its ultraviolet absorption spectrum, have been investigated by the combination of time-resolved total ion yield and photoelectron spectroscopies with high-level ab initio calculations. The...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) |
| Repositorio: | Recercat. Dipósit de la Recerca de Catalunya |
| OAI Identifier: | oai:recercat.cat:10256/13495 |
| Acceso en línea: | http://hdl.handle.net/10256/13495 |
| Access Level: | acceso embargado |
| Palabra clave: | Fotoquímica Photochemistry Ionització Ionization |
| Sumario: | The photochemical and photophysical pathways operative in N-methylpyrrole, after excitation in the near part of its ultraviolet absorption spectrum, have been investigated by the combination of time-resolved total ion yield and photoelectron spectroscopies with high-level ab initio calculations. The results collected are remarkably different from the observations made for pyrrole and other aromatic systems, whose dynamics is dictated by the presence of πσ* excitations on X–H (X: N, O, S, ...) bonds. The presence of a barrier along the C–N dissociation coordinate that can not be tunneled triggers two alternative decay mechanisms for the S1 A″ πσ* state. While at low vibrational content the C–N dissociation occurs on the surface of a lower 3ππ* state reached after efficient intersystem crossing, at higher excitation energies, the A″ πσ* directly internally converts to the ground state through a ring-twisted S1/S0 conical intersection. The findings explain previous observations on the molecule and may be relevant for more complex systems containing similar C–N bonds, such as the DNA nucleotides |
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