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Theses

Ionisation et fragmentation de biomolécules sélectionnées en masse induites par impact d'ions et photo-absorption

Abstract : This work aims at studying fundamental physical and chemical processes induced by ionizing radiation on isolated biomolecules. The first part is devoted to the development and characterization of the experimental set-up PIBALE (Plateforme d'Irradiation de Biomolécules et d'Agrégats Libres et Environnés). The goal of this apparatus is to analyze ion-induced ionization and fragmentation of biologically relevant molecular systems. The biomolecules are produced by means of an electrospray ionization source, mass-over-charge selected, bunched in an ion trap and subsequently extracted to the collision zone. Fragment cations produced during the interaction with the atomic ion beam are analyzed by time-of-flight mass spectrometry. Multi-coincidence detection of the fragments will allow describing the fragmentation kinematics. The second part of this thesis is focused on the gas phase study of a collagen peptide, collagen being the most abundant structural protein in the human body, as well as a hydrogen-bonded collagen triple-helix model. Photo-absorption experiments, from UV to soft X-rays, show that several molecular orbitals can be probed with a single photon and that a smooth transition from excitation to ionization occurs. Above the ionization threshold, the excess energy is distributed into the internal ro-vibrational degrees of freedom and induces inter- followed by intra-molecular dissociation. Thus, photon irradiation could lead to collagen denaturation by the loss of its triple-helix structure. Moreover, collagen-specific fragmentation channels have been found to be triggered by photon absorption.
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  • HAL Id : tel-01465838, version 1

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Lucas Schwob. Ionisation et fragmentation de biomolécules sélectionnées en masse induites par impact d'ions et photo-absorption. Physique [physics]. Université de Caen Normandie, 2016. Français. ⟨tel-01465838⟩

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