Second Harmonic Generation at the Nanoscale: Local Organization and the Birth of Phase Matching
Event details
| Date | 15.04.2024 |
| Hour | 11:00 › 12:00 |
| Speaker | Prof. Pierre-François Brevet, Claude Bernard University Lyon 1 (UCBL), Villeurbanne (FR) |
| Location | |
| Category | Conferences - Seminars |
| Event Language | English |
BIOENGINEERING SEMINAR
Abstract:
Second Harmonic Generation (SHG) is routinely used to convert frequencies in lasers. To achieve the highest rates of conversion, the phase matching rule must be preserved. However, at the nanoscale, this rule no longer drives the SHG response. In the latter case, the response is rather determined by the nanometer scale structure. In this presentation, I will show how SHG can thus provide detailed information about liquid structure, molecular aggregation or nanoparticles shape and size.
We have explored the SHG response from neat liquids like water and aqueous electrolytes. SHG in a scattering mode provides a very detailed picture of the molecular organization induced by intermolecular forces in these liquids [1, 2]. Also, in the case of organic molecules dispersed in a solvent, often used as molecular probes, it is possible to observe aggregation and the formation of micelles.
Nanoparticles present many advantages over organic molecular probes and are now routinely used in microscopy as reporters or for sensing purposes. However, their SHG response is complex and involves both a surface and a volume response. The role of their shape and their size can nevertheless be disentangled [3, 4]. Their large SHG response though opens the possibility to perform single nanoparticle measurements with interesting perspectives for applications [5].
These studies at the nanoscale show how phase matching emerges from randomness in disordered materials, how its coherent nature can be identified and how it can be used to investigate organization in materials at the nanoscale.
[1] J. Duboisset, P.F. Brevet, Salt induced Long-to-Short Range Orientational Transition in Water, Phys. Rev. Lett., 120 (2018) 263001.
[2] J. Duboisset, F. Rondepierre, P.F. Brevet, Long-Range Orientational Organization of Dipolar and Steric Liquids, J. Phys. Chem. Lett., 11 (2020) 9869.
[3] J. Butet, P.F. Brevet, O.J.F. Martin, Optical Second Harmonic Generation in Plasmonic Nanostructures: From Fundamental Principles to Advanced Applications, ACS Nano, 9 (2015) 10545.
[4] L. Bonacina, P.F. Brevet, M. Finazzi, M. Celebrano, Harmonic Generation at the Nanoscale, J. Appl. Phys., 127 (2020) 230901.
[5] L. Sanchez, A. Bruyère, O. Bonhomme, E. Benichou, P.F. Brevet, Longitudinal position dependence of the second-harmonic generation of optically trapped silica microspheres, Opt. Lett., 45 (2020) 3196.
Bio:
After earning a PhD in Molecular Beam Spectroscopy under Prof. Michel Broyer in Lyon, Pierre-François Brevet embarked on a Post-Doctoral fellowship in Edinburgh with Dr. Pat Langridge-Smith, where he investigated electronic states of small clusters. From 1992 to 2000, he worked as a scientist at EPFL, investigating the surface second harmonic generation (SHG) at electrified interfaces, surface SHG of liquid-liquid interfaces, and including nanoparticles at those interfaces (especially gold). In 2000, Dr. Brevet became a Professor at Lyon 1, where his research now focuses on hyper Rayleigh scattering (HRS) of plasmonic nanoparticles and (bio-)molecules, SHG of liquid interfaces including plasmonic nanoparticles and biomolecules, and more recently HRS of liquids.
Abstract:
Second Harmonic Generation (SHG) is routinely used to convert frequencies in lasers. To achieve the highest rates of conversion, the phase matching rule must be preserved. However, at the nanoscale, this rule no longer drives the SHG response. In the latter case, the response is rather determined by the nanometer scale structure. In this presentation, I will show how SHG can thus provide detailed information about liquid structure, molecular aggregation or nanoparticles shape and size.
We have explored the SHG response from neat liquids like water and aqueous electrolytes. SHG in a scattering mode provides a very detailed picture of the molecular organization induced by intermolecular forces in these liquids [1, 2]. Also, in the case of organic molecules dispersed in a solvent, often used as molecular probes, it is possible to observe aggregation and the formation of micelles.
Nanoparticles present many advantages over organic molecular probes and are now routinely used in microscopy as reporters or for sensing purposes. However, their SHG response is complex and involves both a surface and a volume response. The role of their shape and their size can nevertheless be disentangled [3, 4]. Their large SHG response though opens the possibility to perform single nanoparticle measurements with interesting perspectives for applications [5].
These studies at the nanoscale show how phase matching emerges from randomness in disordered materials, how its coherent nature can be identified and how it can be used to investigate organization in materials at the nanoscale.
[1] J. Duboisset, P.F. Brevet, Salt induced Long-to-Short Range Orientational Transition in Water, Phys. Rev. Lett., 120 (2018) 263001.
[2] J. Duboisset, F. Rondepierre, P.F. Brevet, Long-Range Orientational Organization of Dipolar and Steric Liquids, J. Phys. Chem. Lett., 11 (2020) 9869.
[3] J. Butet, P.F. Brevet, O.J.F. Martin, Optical Second Harmonic Generation in Plasmonic Nanostructures: From Fundamental Principles to Advanced Applications, ACS Nano, 9 (2015) 10545.
[4] L. Bonacina, P.F. Brevet, M. Finazzi, M. Celebrano, Harmonic Generation at the Nanoscale, J. Appl. Phys., 127 (2020) 230901.
[5] L. Sanchez, A. Bruyère, O. Bonhomme, E. Benichou, P.F. Brevet, Longitudinal position dependence of the second-harmonic generation of optically trapped silica microspheres, Opt. Lett., 45 (2020) 3196.
Bio:
After earning a PhD in Molecular Beam Spectroscopy under Prof. Michel Broyer in Lyon, Pierre-François Brevet embarked on a Post-Doctoral fellowship in Edinburgh with Dr. Pat Langridge-Smith, where he investigated electronic states of small clusters. From 1992 to 2000, he worked as a scientist at EPFL, investigating the surface second harmonic generation (SHG) at electrified interfaces, surface SHG of liquid-liquid interfaces, and including nanoparticles at those interfaces (especially gold). In 2000, Dr. Brevet became a Professor at Lyon 1, where his research now focuses on hyper Rayleigh scattering (HRS) of plasmonic nanoparticles and (bio-)molecules, SHG of liquid interfaces including plasmonic nanoparticles and biomolecules, and more recently HRS of liquids.
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