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Génération de second harmonique de biomolécules: des acides aminés aux protéines

Abstract : This thesis presents an experimental study of second-harmonic generation of biological molecules. The coherent nature of this process allows obtaining the symmetries of molecules whose size is less than the wavelengths used. The hyperpolarizabilities of aromatic amino acids were measured in solution and the hyperpolarizability of non-aromatic amino acids was measured indirectly through measurements on the collagen molecule. Thus, all the building blocks of proteins are characterized. Among the biological molecules, collagen has a very strong non-linear response despite the absence of harmonophore. A model of coherent summation of the fields reissued to understand the origin of the very high non-linear efficiency from the rigidity and the spatial arrangement of amino acids in triple helix. In the same way, the study of several peptides with one to four tryptophans has enabled us to quantify the importance of conformation and the ionic environment of proteins in the non-linear response. To provide additional information on nano systems, a new setup has been developed, combining two beams of excitation. Thus, the dipole and quadrupole radiation are differentiated to obtain the symmetry of molecular arrangements. Finally, the great sensitivity of the setup allows mapping in three dimensions, with the Hyper Rayleigh scattering, singles metal nanoparticles catch in a gelatin matrix.
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https://tel.archives-ouvertes.fr/tel-00425139
Contributor : Julien Duboisset Connect in order to contact the contributor
Submitted on : Tuesday, October 20, 2009 - 11:57:48 AM
Last modification on : Saturday, September 11, 2021 - 3:04:44 AM
Long-term archiving on: : Tuesday, June 15, 2010 - 9:35:11 PM

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  • HAL Id : tel-00425139, version 1

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Julien Duboisset. Génération de second harmonique de biomolécules: des acides aminés aux protéines. Physique [physics]. Université Claude Bernard - Lyon I, 2009. Français. ⟨tel-00425139⟩

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