There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Signaling Recognition Events with Fluorescent Sensors and Switches.

6. Rehybridization of the Acceptor (RICT) 3908 7. Planarization of the Molecule (PICT) 3909 III. Fluorescence Spectroscopy 3909 A. Solvent Effects and the Model Compounds 3909 1. Solvent Effects on the Spectra 3909 2. Steric Effects and Model Compounds 3911 3. Bandwidths 3913 4. Isoemissive Points 3914 B. Dipole Moments 3915 C. Radiative Rates and Transition Moments 3916 1. Quantum Yields and Radiationless Deactivation Processes 3916

Structural Changes Accompanying Intramolecular Electron Transfer: Focus on Twisted Intramolecular Charge-Transfer States and Structures

Design principles of fluorescent molecular sensors for cation recognition

Crystallographic study and charge density analysis of photo-induced excited states.

L'invention concerne un dispositif electrique comportant deux electrodes separees l'une de l'autre dans lequel au moins une particule a transition d'etat de spin electronique commande en temperature est en contact direct avec chacune des deux electrodes, la particule etant de type ionique et comportant un metal de transition qui porte une charge cationique.

Agencement optimisé de particules de triazole

Up to now, the common media for optical data storage are the discs (blue ray technology for example). However, by definition, this technology is limited to two dimensions. The necessity for increasing data storage capacity requires the use of three-dimensional (3D) optically based systems. One of the methods for 3D optical data storage is based on volume holography. The physical mechanism is photochromism, which is defined as a reversible transformation of a single chemical species between two states that have different absorption spectra and refractive indices. This allows for holographic multiplexing recording and reading, such as wavelength (Rakuljic et al., 1992), angular (Mok, 1993), shift (Psaltis et al., 1995) and phase encoding. Another promising 3D optical data storage system is the bit-by-bit memory at the nanoscale (Li et al., 2007). It is based on the confinement of multi-photon absorption to a very small volume because of its nonlinear dependence on excitation intensity. This characteristic provides an income for activating chemical or physical processes with high spatial resolution in three dimensions. As a result there is less cross talk between neighbouring data layers. Another advantage of multi-photon excitation is the use of infrared (IR) illumination, which results in the reduction of scattering and permits the recording of layers at a deep depth in a thick material. Two-photon 3D bit recording in photopolymerizable (Strickler & Webb, 1991), photobleaching (Pan et al., 1997; Day & Gu, 1998) and void creation in transparent materials (Jiu et al., 2005; Squier & Muller, 1999) has been demonstrated with a femtosecond laser. Recording densities could reach terabits per cubic centimeter. Nevertheless, these processes suffer from several drawbacks. The index modulation associated with high bit density limits the real data storage volume due to light scattering. The fluorescence can limit the data transfer rate and the lifetime of the device. Thanks to various available compositions, ease of implementation, stability and transparency, both organic and inorganic materials are convenient for 3D data storage. To be good candidates for 3D optical data storage, these materials must satisfy several norms 3

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Optical Data Storage in Photosensitive Glasses and Spin State Transition Compounds

La presente invention concerne un procede de photocommutation thermique de composes a transition de spin de l'etat bas-spin vers l'etat haut-spin, comprenant au moins une etape d'exposition dudit materiau a un rayonnement laser non polarise a une longueur d'onde comprise dans l'infrarouge, a temperature ambiante et a une puissance de 1 mWcm -2 a 1 Wcm -2  Elle concerne egalement l'utilisation d'un tel procede pour le marquage temporaire ou permanent de materiaux comprenant des particules d'au moins un compose a transition de spin comprenant un compose a base de fer(II) et d'un ligand triazole

Procede de photocommutation thermique de materiaux a transition de spin et applications

La presente invention concerne un procede de visualisation d'un rayonnement electromagnetique terahertz, comprenant une etape d'exposition d'un materiau a un rayonnement electromagnetique terahertz ayant une densite de puissance superieure ou egale a un seuil predetermine de densite de puissance, dans laquelle ledit materiau est un materiau comprend un compose a transition de spin, ladite transition etant associee a une transition du coefficient d'absorption du materiau dans le domaine visible adaptee pour visualiser ledit rayonnement electromagnetique L'invention concerne egalement un dispositif de visualisation d'un rayonnement electromagnetique terahertz comprenant : un substrat et une couche de materiau comprenant un compose a transition de spin, ladite transition de spin etant associee a une transition du coefficient d'absorption du materiau dans le domaine visible adaptee pour visualiser ledit rayonnement electromagnetique terahertz lorsque ladite couche est exposee au rayonnement electromagnetique terahertz ayant une densite de puissance superieure ou egale a un seuil predetermine de densite de puissance

Jean-François Létard

Papers

Crystallographic study and charge density analysis of photo-induced excited states.

Agencement optimisé de particules de triazole

Optical Data Storage in Photosensitive Glasses and Spin State Transition Compounds

Procede de photocommutation thermique de materiaux a transition de spin et applications

Procede et dispositif de visualisation d'un rayonnement electromagnetique terahertz