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SUMMARY:Second Harmonic Generation at the Nanoscale: Local Organization an
 d the Birth of Phase Matching
DTSTART:20240415T110000
DTEND:20240415T120000
DTSTAMP:20260417T142834Z
UID:1f75d1c495475ca298aa91cc37fd93191cbd6f66c680dfec04ae53b1
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Pierre-François Brevet\, Claude Bernard University Lyon
  1 (UCBL)\, Villeurbanne (FR)\nBIOENGINEERING SEMINAR\n \nAbstract:\nSeco
 nd Harmonic Generation (SHG) is routinely used to convert frequencies in l
 asers. To achieve the highest rates of conversion\, the phase matching rul
 e must be preserved. However\, at the nanoscale\, this rule no longer driv
 es the SHG response. In the latter case\, the response is rather determine
 d by the nanometer scale structure. In this presentation\, I will show how
  SHG can thus provide detailed information about liquid structure\, molecu
 lar aggregation or nanoparticles shape and size.\n\nWe have explored the S
 HG response from neat liquids like water and aqueous electrolytes. SHG in 
 a scattering mode provides a very detailed picture of the molecular organi
 zation induced by intermolecular forces in these liquids [1\, 2]. Also\, i
 n the case of organic molecules dispersed in a solvent\, often used as mol
 ecular probes\, it is possible to observe aggregation and the formation of
  micelles.\n\nNanoparticles present many advantages over organic molecular
  probes and are now routinely used in microscopy as reporters or for sensi
 ng purposes. However\, their SHG response is complex and involves both a s
 urface and a volume response. The role of their shape and their size can n
 evertheless be disentangled [3\, 4]. Their large SHG response though opens
  the possibility to perform single nanoparticle measurements with interest
 ing perspectives for applications [5].\n\nThese studies at the nanoscale s
 how how phase matching emerges from randomness in disordered materials\, h
 ow its coherent nature can be identified and how it can be used to investi
 gate organization in materials at the nanoscale.\n\n\n[1]        J.
  Duboisset\, P.F. Brevet\, Salt induced Long-to-Short Range Orientational 
 Transition in Water\, Phys. Rev. Lett.\, 120 (2018) 263001.\n[2]     
    J. Duboisset\, F.  Rondepierre\, P.F. Brevet\, Long-Range Orientatio
 nal Organization of Dipolar and Steric Liquids\, J. Phys. Chem. Lett.\, 11
  (2020) 9869.\n[3]        J. Butet\, P.F. Brevet\, O.J.F. Martin\, 
 Optical Second Harmonic Generation in Plasmonic Nanostructures: From Funda
 mental Principles to Advanced Applications\, ACS Nano\, 9 (2015) 10545.\n[
 4]        L. Bonacina\, P.F. Brevet\, M. Finazzi\, M. Celebrano\, H
 armonic Generation at the Nanoscale\, J. Appl. Phys.\, 127 (2020) 230901.\
 n[5]        L. Sanchez\, A. Bruyère\, O. Bonhomme\, E. Benichou\, P
 .F. Brevet\, Longitudinal position dependence of the second-harmonic gener
 ation of optically trapped silica microspheres\, Opt. Lett.\, 45 (2020) 31
 96.\n\nBio:\nAfter earning a PhD in Molecular Beam Spectroscopy under Prof
 . Michel Broyer in Lyon\, Pierre-François Brevet embarked on a Post-Docto
 ral fellowship in Edinburgh with Dr. Pat Langridge-Smith\, where he invest
 igated electronic states of small clusters. From 1992 to 2000\, he worked 
 as a scientist at EPFL\, investigating the surface second harmonic generat
 ion (SHG) at electrified interfaces\, surface SHG of liquid-liquid interfa
 ces\, and including nanoparticles at those interfaces (especially gold). I
 n 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 nanoparticl
 es and biomolecules\, and more recently HRS of liquids.\n 
LOCATION:CM 1 104 https://plan.epfl.ch/?room==CM%201%20104
STATUS:CONFIRMED
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