Destabilization of dark states and optical spectroscopy in Zeeman-degenerate atomic systems

We present a general discussion of the techniques of destabilizing dark states in laser-driven atoms with either a magnetic field or modulated laser polarization. We show that the photon scattering rate is maximized at a particular evolution rate of the dark state. We also find that the atomic resonance curve is significantly broadened when the evolution rate is far from this optimum value. These results are illustrated with detailed examples of destabilizing dark states in some commonly-trapped ions and supported by insights derived from numerical calculations and simple theoretical models.Comment: 14 pages, 10 figure

Sur l'origine d'un déplacement radiatif observé en modulation spatiotemporelle des jets moléculaires

Au voisinage d'une résonance d'un jet moléculaire, le spectre de modulation produit par une cellule d'irradiation ayant une structure spatiale périodique, montre des composantes subissant un déplacement de type Bloch-Siegert et un autre déplacement lié au temps d'interaction et qui résulte des interférences des probabilités de transition dues aux deux composantes résonnante et antirésonnante du champ d'irradiation

Sur l'origine d'un déplacement radiatif observé en modulation spatiotemporelle des jets moléculaires

When a modular beam is irradiated near the molecular resonance by an irradiation cell having a periodic structure, one observes a spectrum, the components of which can have a displacement of the Bloch-Siegert type and a displacement bound to the interaction time. We propose an analysis of the second one which we explain by interferences of transition probabilities.Au voisinage d'une résonance d'un jet moléculaire, le spectre de modulation produit par une cellule d'irradiation ayant une structure spatiale périodique, montre des composantes subissant un déplacement de type Bloch-Siegert et un autre déplacement lié au temps d'interaction et qui résulte des interférences des probabilités de transition dues aux deux composantes résonnante et antirésonnante du champ d'irradiation

Reaction of 2-benzoyl-1,2-dihydroisoquinaldonitrile hydrofluoroborate salt with some 1,4 quinones

International audienc

Reaction of 2-benzoyl-1,2-dihydroisoquinaldonitrile hydrofluoroborate salt with some 1,4 quinones

International audienc

Tuning of Metal/Insulator Transition around Room Temperature of Perovskites Sm1-xNdxNiO3

International audienceWe report here a study of the synthesis and properties of the solid solution series Sm1-xNdxNiO3. It was found to crystallize in the GdFeO3-type orthorhombically distorted perovskite structure, The metal-insulator (M/I) transition was mapped out as a function of the composition, It is possible to control this transition between 200 and 410 K by simply adjusting the composition. For instance, the MII transition occurs at room temperature for Sm0.55Nd0.45NiO3, and the variation of the transition temperature with composition is about 2.3 K/x%. These phase transitions have been studied by differential scanning calorimetry, microwave procedure, and X-ray diffraction. Microwave data reveal hysteresis effects, An interpretation of the experimental results may be the coexistence of the metallic and insulating phases. On the other hand, we have observed that the enthalpy change of phase transition decreases when the powder is ground. This phenomenon can be related to amorphization of the material