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Saturated and benzylic organomagnesium compounds are shown to readily undergo addition reactions with the conjugated enynes HCHCH2R′, with R′ = alkyl, OH, OC4H9, NHC25, N(C2H5)2, by refluxing for several hours in benzene or toluene.This reaction leads to both υ-acetylenic compounds (1,2-addition) and β-allenic compounds (1,4-addition). 相似文献
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M. Bouchdoug A. Courtois R. Gerardin J. Steinmetz C. Gleitzer 《Journal of solid state chemistry》1982,42(2):149-157
This compound is obtained in several ways, at 900°C, from the components of the FePO system when the oxygen pressure is made suitable, or from Fe3(PO4)2 + Fe + Fe2O3 in a sealed tube under vacuum. It crystallizes under these latter conditions with a trace of FeCl2. The cell is monoclinic; a = 6.564(1), b = 11.271(2), c = 9.383(2) Å, β = 103.95 (2)°, with Z = 4, group . The structure is determined thanks to the use of a direct method and Fourier synthesis and is refined to R = 0.033. The PO4 tetrahedra are isolated; the iron fills four crystallographic sites: three are more or less distorted octahedra, the fourth is a trigonal bipyramid. The oxyphosphate character is ascertained by the presence of some oxygen atoms connected to iron only, with, moreover, a low site potential. This compound is paramagnetic above 90°K. Its Mössbauer spectrum exhibits four doublets in good agreement with the structure; in order to identify which one corresponds to the hexahedral site, the phase Fe3Zn(PO4)2O has been prepared, but its Mössbauer spectrum, in spite of the zinc affinity for the V coordination, shows that two sites are modified, which does not allow conclusions to be made. 相似文献
5.
Assuming that a North-South transfer is the key to effective climate cooperation, we ask when and how much the North should offer to the South in return for a commitment to reduce deforestation and forest degradation. In light of the risk of irreversible damage over time, we examine a negotiation with a deadline. In this case, the North threatens the South over a negotiation dead-end in case an agreement is not reached rapidly. We assess the conditions for an agreement to be immediate or delayed, and discuss those situations likely to result in negotiation failure. Despite the risk of irreversible damage over time, we show that cooperation is likely to be delayed and we identify situations wherein the North and South do not reach an agreement within the deadline. Although Pareto-improving, cooperation may collapse because of inefficiencies related to incomplete information. What’s more, we show that in negotiations with a deadline, uncertainty about the benefits deriving from cooperation and the irreversibility of the damage that will be caused if cooperation is delayed are the two key components affecting choice. 相似文献
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Dr. Damien Hudry Dr. Christos Apostolidis Dr. Olaf Walter Dr. Thomas Gouder Dr. Eglantine Courtois Dr. Christian Kübel Dr. Daniel Meyer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(17):5297-5305
Very little is known about the size and shape effects on the properties of actinide compounds. As a consequence, the controlled synthesis of well‐defined actinide‐based nanocrystals constitutes a fundamental step before studying their corresponding properties. In this paper, we report on the non‐aqueous surfactant‐assisted synthesis of thorium and uranium oxide nanocrystals. The final characteristics of thorium and uranium oxide nanocrystals can be easily tuned by controlling a few experimental parameters such as the nature of the actinide precursor and the composition of the organic system (e.g., the chemical nature of the surfactants and their relative concentrations). Additionally, the influence of these parameters on the outcome of the synthesis is highly dependent on the nature of the actinide element (thorium versus uranium). By using optimised experimental conditions, monodisperse isotropic uranium oxide nanocrystals with different sizes (4.5 and 10.7 nm) as well as branched nanocrystals (overall size ca. 5 nm), nanodots (ca. 4 nm) and nanorods (with ultra‐small diameters of 1 nm) of thorium oxide were synthesised. 相似文献
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C. Mennerat-Robilliard L. Guidoni K.I. Petsas P. Verkerk J.-Y. Courtois G. Grynberg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(1):33-45
All the bright optical lattices studied so far have been designed to obtain a circularly polarized light at the bottom of
the optical potential wells. This condition minimizes the departure rate of the atoms from the fundamental adiabatic surface
and permits an oscillating regime in a large range of parameters. We present here an experimental study of cesium atoms in
a three-dimensional optical lattice, where the light is linearly polarized at the bottom of the potential wells. Temperature
measurements and pump-probe spectroscopy give similar results for this lattice and for the conventional lin lin lattice (which have circular polarizations at the bottom of the wells) despite the fact that one lattice operates in
the jumping regime and the other in the oscillating regime. We study the behaviour of the two types of lattices in a longitudinal
magnetic field, with particular emphasis on the zero field and strong field regimes. The strong field situation is very simple
because the eigenstates are then almost pure Zeeman substates and the adiabatic and diabatic potential surfaces are identical.
The comparison between the zero-field and the high-field situations shows that the diabatic potentials are more appropriate
to account for experimental observations in the novel lattice.
Received: 9 October 1997 / Accepted: 6 November 1997 相似文献
10.
L. Joly V. Zéninari B. Parvitte D. Weidmann D. Courtois Y. Bonetti T. Aellen M. Beck J. Faist D. Hofstetter 《Applied physics. B, Lasers and optics》2003,77(6-7):703-706
We report results of spectroscopic measurements with a continuous-wave distributed-feedback quantum-cascade laser (DFB QCL). Line intensities and self-broadening coefficients were measured in the 1 band of SO2 between 1088 and 1090 cm-1. The self-broadening coefficients in this paper confirm the typical decrease of self with increasing rotational quantum number Ka
. The line intensities determined here are smaller than those in the HITRAN 2000 database. Several lines found in this study were not present in the database. PACS 07.57.Ty; 33.20.Ea 相似文献