Search results for "molécula"
showing 10 items of 109 documents
Les matériaux pour capteurs chimiques
2002
National audience; A chemical sensor is composed of one part supplying chemical reco gnition coupled to one transducingsystem. At the recognition origin, interaction with the target chemical species is oftwo types, either electronicexchange, or ionic exchange. Two large classes of materials that can supply recognition proceed: metals andsemiconductors giving rise to electronic exchange and ionic conducting materials giving rise to ionic exchan-ge. This paper is structured in tw o large parts, emphasizing on materi als inducing specific interactions:semiconductor materials (metallic oxides and molecular semiconductors) and ionic conductor materials.In each part will be presented nature of ma…
Effet de l'humidité sur la réponse à l'ammoniac de capteurs conductimétriques à base de matériaux moléculaires
2012
Many ammonia sensors are available but the consideration of the humidity effect is scarcely insured even by manufacturers. The aim of this thesis is to propose a conductimetric transducer capable tomeasure ammonia selectively, with enough accuracy for air quality control, in a variable humidity environment. To reach this goal, we used thin film resistors made of cobalt phthalocyanines as semiconductor. This study deals with thin films processing made by vacuum evaporation, solventcast and electrodeposition. Automated workbenches were developed to perform electrical measurements under argon and to study the response of sensors to dry or humid ammonia by meansof 1 min / 4 min-long exposure / …
Development of a microwave transduction gas sensor
2013
In this work, we have developed a new gas-sensing transduction based on the propagation of microwave inside a sensitive material to detect atmospheric pollutants at room temperature. First, we present a short overview of the main gas-sensing transduction in the litterature. These techniques operate in frequency ranges different from microwaves. The dielectric permittivity is the main physical parameter in the microwave transduction. The principle is based on the excitation of a sensitive material by a microwave electromagnetic field in a propagative structure. The reflected wave is specific to the excitation's frequency. It depends on the interaction between the sensitive material and the p…
Bioinorganic Chemistry Chapter 2
2018
Tema 2 de la part de Bioinorgànica de l'assignatura Química Inorgànica Avançada Chapter 2 of the Bioinorganic part of the subject Advanced Inorganic Chemistry
Estudio de imanes moleculares de Co(ii): desde sistemas aislados hasta sistemas organizados y multifuncionales
2016
Dentro de la disciplina conocida como Magnetismo Molecular, y a raíz del descubrimiento del Mn12 en 1993, ha surgido un gran interés por las moléculas que presentan una lenta relajación de la magnetización por debajo de una temperatura de bloqueo. A estas moléculas se les conoce como Imanes Unimoleculares (Single Molecule Magnets, SMMs). En la última década, la utilización de compuestos con un único centro metálico paramagnético (Single Ion Magnets, SIMs) se ha postulado como una de las nuevas estrategias utilizadas para la obtención de compuestos que presentan lenta relajación de la magnetización con barreras efectivas más elevadas. Además, desde un punto de vista experimental y teórico, l…
Estudio de propiedades magnéticas en compuestos de coordinación multifuncionales
2021
En las últimas décadas, las moléculas imán han atraído la atención de la comunidad científica, puesto que permitirían superar las limitaciones actuales de almacenamiento en dispositivos y, también, por su interés en espintrónica. El descubrimiento de las moléculas imán polinucleares (SMMs) fue impactante, pues presentan lenta relajación de la magnetización por debajo de una cierta temperatura. Por tanto, el desarrollo de moléculas imán mononucleares (SIMs) basadas en iones CoII, como único centro paramagnético responsable de ese comportamiento, son de interés por su alto espín (S = 3/2) y un inherente desdoblamiento a campo cero (zfs), que se puede modificar dependiendo de la geometría impu…
ALIGNEMENT UNI ET TRIDIMENSIONNEL DE MOLÉCULES PAR IMPULSION LASER FEMTOSECONDE
2007
This thesis is devoted to the study of the alignment of linear and asymmetric top molecules generated by an intense laser pulse. In the case of short pulses with respect to molecular rotation, periodic alignment appears in field-free conditions after the extinction of the field. We study theoretically and experimentally the effects of intensity, temperature and polarization of the electric field on produced alignment. If the field is linearly polarized, the interaction leads to the alignment of the most polarizable axis of the molecule. If the field is elliptically polarized, the pulse can generate a simultaneous alignment of the three principal axes of inertia of an asymmetric top molecule…
Mesure de l'effet Kerr d'ordre élevé des constituants de l'air
2009
Talk given by V. Loriot
From the spherical top to the asymmetric top
2004
This habilitation report presents a synthesis of my research work during the last 14 years. I have distinguished my experimental activities (part III), my theoretical work on the spectroscopy of quasi-spherical tops (part IV) and that concerning the spectroscopy of molecules trapped in solids (part V).
Dynamics and toxicity of proteins with a high homology of sequences: approach by molecular dynamics and ab-initio calculations
2008
The elucidation of the structure and the biological function of proteins is a major stake for its implications in the biomedical research as well as in biotechnologies. In addition, there is a glass or dynamical transition for the proteins which occurs at around 200K: it has been observed by Neutron Scattering, X-ray diffraction and Mossbauer spectroscopy for different proteins. Above the transition temperature, the biological function is activated as the protein may diffuse between conformational sub-states. The microscopic origin of this transition is still debated in spite of significant advances in recent years showing the significant role of hydration. By using all-atoms classical mole…