First hyperpolarizability of water at the air–vapor interface: a QM/MM study questions standard experimental approximations
| Autor: | Pierre-François Brevet, Emmanuel Benichou, Claire Loison, Oriane Bonhomme, Guillaume Le Breton |
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| Přispěvatelé: | Physico-chimie théorique (THEOCHEM), Institut Lumière Matière [Villeurbanne] (ILM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Optique non linéaire et interfaces (ONLI) |
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Physics
010304 chemical physics General Physics and Astronomy Hyperpolarizability Second-harmonic generation Water Interface Quantum Chemistry 010402 general chemistry Molecular Dynamics 01 natural sciences Molecular physics Quantum chemistry 0104 chemical sciences Second Harmonic Generation [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry Dipole Molecular dynamics 0103 physical sciences Surface second harmonic generation Tensor Physical and Theoretical Chemistry Quantum |
| Zdroj: | Physical Chemistry Chemical Physics Physical Chemistry Chemical Physics, Royal Society of Chemistry, 2021, 23 (43), pp.24932-24941. ⟨10.1039/D1CP02258J⟩ |
| ISSN: | 1463-9076 1463-9084 |
| Popis: | International audience; Surface Second-Harmonic Generation (S-SHG) experiments provide a unique approach to probe interfaces. One important issue for S-SHG is how to interpret the S-SHG intensities at the molecular level. Established frameworks commonly assume that each molecule emits light according to an average molecular hyperpolarizability tensor β(−2ω,ω,ω). However, for water molecules, this first hyperpolarizability is known to be extremely sensitive to their environment. We have investigated the molecular first hyperpolarizability of water molecules within the liquid–vapor interface, using a quantum description with explicit, inhomogeneous electrostatic embedding. The resulting average molecular first hyperpolarizability tensor depends on the distance relative to the interface, and it practically respects the Kleinman symmetry everywhere in the liquid. Within this numerical approach, based on the dipolar approximation, the water layer contributing to the Surface Second Harmonic Generation (S-SHG) intensity is less than a nanometer. The results reported here question standard interpretations based on a single, averaged hyperpolarizability for all molecules at the interface. Not only the molecular first hyperpolarizability tensor significantly depends on the distance relative to the interface, but it is also correlated to the molecular orientation. Such hyperpolarizability fluctuations may impact the S-SHG intensity emitted by an aqueous interface. |
| Databáze: | OpenAIRE |
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