Ground-State Structural Disorder and Excited-State Symmetry Breaking in a Quadrupolar Molecule

Article Article scientifique Article Ground-State Structural Disorder and Excited-State Symmetry Breaking in a Quadrupolar Molecule eng 2019 author Soederberg Carl Magnus 861436 author Dereka Bogdan 802005 author Marrocchi Assunta author Carlotti Benedetta author Vauthey Eric 0000-0002-9580-9683 133895 2944-2948 10.1021/acs.jpclett.9b01024 1948-7185 https://pubs.acs.org/doi/10.1021/acs.jpclett.9b01024 The influence of torsional disorder around the ethynyl π-bridges of a linear D−π–A−π–D molecule on the nature of its S1 excited state was investigated using ultrafast time-resolved infrared spectroscopy. By tuning the pump wavelength throughout the S1 ← S0 absorption band, subpopulations with different extents of asymmetry could be excited. In nonpolar solvents, the equilibrated S1 state is symmetric and quadrupolar independently of the initial degree of distortion. Photoexcitation of distorted molecules is followed by planarization and symmetrization of the S1 state. Excited-state symmetry breaking is only observed in polar environments, where the equilibrated S1 state has a strong dipolar character. However, neither the extent nor the rate of symmetry breaking are enhanced in an initially distorted molecule. They are only determined by the polarity and the dynamic properties of the solvent. Dewey 540 Swiss National Science Foundation Applications de la spectroscopie ultrarapide à l'étude de processus photoinduits en phase condensée 184607 CH Project funding 38 Département de chimie physique 142 false 686 Groupe Vauthey http://doi.org/10.5281/zenodo. 2635474. Journal of Physical Chemistry Letters 10 11 0002ea3e-7f71-4c5c-836b-6a7abf97c577 Article (Published version) Public SoederbergJPCL19.pdf 1175920 application/pdf OA OTHER openAccess Faculté des sciences / Section de chimie et biochimie / Département de chimie physique

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Ground-State Structural Disorder and Excited-State Symmetry Breaking in a Quadrupolar Molecule	Journal of Physical Chemistry Letters			2019	360	251

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Soederberg, Carl Magnus