Chemical kinetics in an atmospheric pressure helium plasma containing humidity

Atmospheric pressure plasmas are sources of biologically active oxygen and nitrogen species, which makes them potentially suitable for the use as biomedical devices. Here, experiments and simulations are combined to investigate the formation of the key reactive oxygen species, atomic oxygen (O) and hydroxyl radicals (OH), in a radio-frequency driven atmospheric pressure plasma jet operated in humidified helium. Vacuum ultra-violet high-resolution Fourier-transform absorption spectroscopy and ultra-violet broad-band absorption spectroscopy are used to measure absolute densities of O and OH. These densities increase with increasing H 2 O content in the feed gas, and approach saturation values at higher admixtures on the order of 3 × 10 14 cm −3 for OH and 3 × 10 13 cm −3 for O. Experimental results are used to benchmark densities obtained from zero-dimensional plasma chemical kinetics simulations, which reveal the dominant formation pathways. At low humidity content, O is formed from OH + by proton transfer to H 2 O, which also initiates the formation of large cluster ions. At higher humidity content, O is created by reactions between OH radicals, and lost by recombination with OH. OH is produced mainly from H 2 O + by proton transfer to H 2 O and by electron impact dissociation of H 2 O. It is lost by reactions with other OH molecules to form either H 2 O + O or H 2 O 2 . Formation pathways change as a function of humidity content and position in the plasma channel. The understanding of the chemical kinetics of O and OH gained in this work will help in the development of plasma tailoring strategies to optimise their densities in applications

Synthese de metalloporphyrines fonctionnelles en vue d'applications en hematologie et imagerie medicale

Available from INIST (FR), Document Supply Service, under shelf-number : TD 82006 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Etude de dérivés de molécules cages (synthèses et caractérisations de plateformes moléculaires)

ORLEANS-BU Sciences (452342104) / SudocSudocFranceF

Analyse en temps réel par spectrométrie de masse haute résolution de molécules à l'état de traces

National audienc

Bis antennae amphiphilic cyclodextrins: the first examples.

International audienc

On the origin of some cubebene derivatives — Diels–Alder adducts and the diene structures of solidago compounds

International audienceAbstract: Two reactions, HCl addition and the thermal and (or) microwave assisted Diels–Alder condensation, were performed on α-cubebene (1), a vinylcyclopropane-containing tricyclic sesquiterpene. The diene structures originating from these reactions and from subsequent rearrangements of 1were identified. The stereochemistry of the resulting ad-ducts was established using mostly 2D high-resolution NMR.Résumé : Leα-cubébène (1), un sesquiterpène qui contient une unité vinylcyclopropane, a été soumis à une réaction d’addition de HCl et une de condensation de Diels–Alder thermique à l’aide de microondes. On a identifié les structures diéniques qui trouvent leur origine dans ces réactions et dans les réarrangements subséquents du composé 1. On a déterminé la stéréochimie des adduits qui en résultent en se basant principalement sur la RMN bidimensionnelle à haute résolution