Magnetic properties of erbium iron garnet in high magnetic fields up to 150kOe

The magnetic properties of single crystals of erbium iron garnet (ErIG) were studied in applied fields up to 150kOe between 1.4 and 300K. At low temperature, the macroscopic easy direction of the bulk magnetization is [100]; below the compensation temperature (80±2K), the magnetization presents non-linear field evolution. On the assumption of an isolated ground doublet, the anisotropy constantsK _i (i=1,2) of ErIG are given byK _i (Er)+K _i (YIG); theK _i are calculated as a function of theG andg tensor components. It is worthwhile noting that theK _i (Er) are strongly temperature dependent; so at low temperature the anisotropy of the garnet is determined by the rare earth ions, while in the 50 K regionK ₁(Er) becomes comparable toK ₁(YIG) with the opposite sign which results in a very weak anisotropy of the garnet. Above 50 K,K ₁(YIG) is predominant and the Fe³⁺ ions determine the garnet anisotropy.     

Observation of level splitting within the natural width by saturation spectroscopy

A saturation-spectroscopy experiment is performed in a three-level system in Xe I, and shows that a narrow dip occurs in the power-broadened Lorentzian response. It is due to the Zeeman splitting of common level by the earth magnetic field. Other splittings, typically larger than 0.2 the natural width, can be observed using this saturation effect. Interpretation is made on the basis of simple realistic assumptions. Associé à l'Université Paris-Sud     

Deformation change between184mAu and184gAu

Isotope shift and hyperfine structure measurements have been performed on the short lived¹⁸⁴Au nucleus using the COMPLIS apparatus installed at ISOLDE. The charge radius change and the magnetic and quadrupole moments of both isomeric and ground states have been deduced. The¹⁸⁴Au ground state appears to be slightly more deformed than the isomeric state.     

MCVD preform central dip reduction by collapse under fluorinated atmosphere

MCVD preforms with a doped core are known to have a central index depression which can have a noticeable influence on the fiber transmission properties. The magnitude of the dip can be reduced by carrying out an etching treatment with a fluorine compound during the collapse preliminary steps.     

Evaporation residue cross sections in complete fusion reactions between52Cr-56Fe,63Cu-Ni and63Cu-Ag

Evaporation residue cross sections have been measured by the technique of the telescopeΔE ·E counter at very small angles. The angular distribution has been followed down to 2°15′, and rather precise values were obtained for that fraction of the compound nucleus decay after complete fusion for the systems⁶³Cu+Ni,⁶³Cu+Ag and⁵²Cr+⁵⁶Fe at two bombarding energies. A comparison has been done with evaporation calculations using the code ALICE, and the rotating liquid drop concept. It is shown that a large discrepancy occurs at low energy for these heavy projectiles. The origin of this difference is discussed.     

Transformations microbiologiques-3 : Approche de la topologie du site hydroxylant de beauveria sulfurescens

Hydroxylation of some bi- or tricyclic amides or lactams, the determination of the absolute configuration of the alcohols obtained and the topology of the hydroxylating site of Beauveria sulfurescens based on these absolute configurations, are discussed.     

Monofunctional (Dimethylamino)silane as Silylating Agent

The reaction of triorganyl(dimethylamino)silanes with surface-hydrated silicon dioxide has been studied. These silylating agents are easy to prepare from the corresponding chloro or bromosilanes with dimethylamine. The resulting products are thermally stable and relatively volatile. Reaction with surface-hydrated silicon-dioxide preparations at 150–250°C for 170 h yields a dense grafted layer. However, with (dimethylamino)silanes having strongly polar substituents, a retreatment of the surface-modified silica seems to be necessary in order to attain maximum coverage.