Comparing the electronic relaxation dynamics of aniline and d7-aniline following excitation at 272–238 nm

Oliver M. Kirkby; Matthieu Sala; Garikoitz Balerdi; Rebeca de Nalda; Luis Bañares; Stéphane Guérin; Helen H. Fielding

doi:10.1039/C5CP01883H

Comparing the electronic relaxation dynamics of aniline and d₇-aniline following excitation at 272–238 nm†

Oliver M. Kirkby,^a Matthieu Sala,^b Garikoitz Balerdi,^c Rebeca de Nalda,^d Luis Bañares,^c Stéphane Guérin^b and Helen H. Fielding*^a

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* Corresponding authors

^a Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK
E-mail: h.h.fielding@ucl.ac.uk

^b Laboratoire Interdisciplinaire Carnot de Bourgogne UMR 6303 CNRS, Université Bourgogne Franche-Comté, 9 Av. A. Savary, BP 47870, F-21078 Dijon Cedex, France

^c Departamento de Química Física I (Unidad Asociada I + D + i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain

^d Instituto de Química Física Rocasolano, CSIC, C/Serrano 119, 28006 Madrid, Spain

Abstract

Femtosecond time-resolved photoelectron spectroscopy experiments have been used to compare the electronic relaxation dynamics of aniline and d₇-aniline following photoexcitation in the range 272–238 nm. Together with the results of recent theoretical investigations of the potential energy landscape [M. Sala, O. M. Kirkby, S. Guérin and H. H. Fielding, Phys. Chem. Chem. Phys., 2014, 16, 3122], these experiments allow us to resolve a number of unanswered questions surrounding the nonradiative relaxation mechanism. We find that tunnelling does not play a role in the electronic relaxation dynamics, which is surprising given that tunnelling plays an important role in the electronic relaxation of isoelectronic phenol and in pyrrole. We confirm the existence of two time constants associated with dynamics on the 1¹πσ* surface that we attribute to relaxation through a conical intersection between the 1¹πσ* and 1¹ππ* states and motion on the 1¹πσ* surface. We also present what we believe is the first report of an experimental signature of a 3-state conical intersection involving the 2¹ππ*, 1¹πσ* and 1¹ππ* states.

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DOI: https://doi.org/10.1039/C5CP01883H
Article type: Paper
Submitted: 31 Mar 2015
Accepted: 13 May 2015
First published: 14 May 2015
This article is Open Access

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Phys. Chem. Chem. Phys., 2015,17, 16270-16276

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Comparing the electronic relaxation dynamics of aniline and d₇-aniline following excitation at 272–238 nm

O. M. Kirkby, M. Sala, G. Balerdi, R. de Nalda, L. Bañares, S. Guérin and H. H. Fielding, Phys. Chem. Chem. Phys., 2015, 17, 16270 DOI: 10.1039/C5CP01883H

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