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91.
Metallatriazadiphosphorine complexes corresponding to [{N(PPh2NR)2}M(OAc)] and [{N(PPh2NR)2}2M], (R = Ph or SiMe3; M = Zn, Cd or Hg) have been synthesized under strictly anhydrous and inert conditions by the reaction of the acyclic bis-silylated phosphazene ligand, [HN(PPh2NSiMe3)2], or the bis-phenylated phosphazene ligand, [HN(PPh2NPh)2], with Zn, Cd and Hg acetate in 1:1 and 2:1 molar ratios. These complexes are highly soluble in common organic solvents, but unstable hydrolytically as well as thermally, even under reduced pressure. Molecular weight determinations in benzene indicated the monomeric nature of these complexes. Further, they have been characterized on the basis of elemental analysis and spectral studies: i.r. and n.m.r. (1H, 13C and 31P) that plausibly reveal a trigonal planar and tetrahedral geometry around the metal atom in the complexes. 相似文献
92.
Molar excess volumes of mixing VE for binary mixtures of furfuryl alcohol with the aromatic hydrocarbons benzene, toluene, ethylbenzene, and o-, m-, and p-xylene were determined for the entire composition range at 25°C. VE was negative for the mixtures containing benzene, toluene and pxylene but positive for mixtures containing ethylbenzene and o- and m-xylene. The results are discussed in terms of specific interaction present in the binary mixture and are compared with those previously reported for tetrahydrofuran, fur an or furfural binary mixtures with aromatic hydrocarbons. 相似文献
93.
We have measured the zero-field a.c. susceptibility of five glasses, containing varying amounts of Fe and Ni ions, in the temperature region 1 K to 150 K. Most of the glasses show spin-glass behaviour with spin-freezing temperature in the region of 1 K to 4 K. From the overall data we conclude that: 1) the interaction between the iron ions in these glasses is antiferromagnetic; 2) the introduction of Ni ions reduces the antiferromagnetic interaction between Fe ions. 相似文献
94.
The paper describes a simple and cost effective method for the realization of an optical interferometer based on holographic
optics, which use minimal bulk optical components. The optical arrangement in the proposed method involves a very simple alignment
procedure and inexpensive holographic recording material is used in the formation of holographic optical elements. The proposed
interferometer set-up is quite suitable for performing optical test studies on phase (transparent) objects in real-time. Recording
schemes for the formation of holographic optical elements and the related technique for the realization of the interferometer
set-up along with the experimental results have been presented. 相似文献
95.
Gerard Bacquet Claude Bouysset Sushil K. Misra 《Journal of Physics and Chemistry of Solids》1980,41(4):397-400
X-band room temperature EPR spectra have been recorded for Mn2+ ion doping unannealed (La2O3)0.95(CeO2)0.05 host crystal. The data are analysed using a rigorous least-squares fitting procedure in which a large number of lines characterized by ΔM = ± 1, Δm = 0 transition, obtained for several orientations of the static magnetic field, are simultaneously fitted. Combined with the knowledge of the absolute sign of the hyperfine interaction parameter. A, the hyperfine Hamiltonian parameters A, B, Q as reported in this paper, are given with their correct signs. The information on the linewidth is used to deduce the deviation of the crystal-field axes of different Mn2+ ions from the c axis; on the basis of the model proposed here these deviations are found to be between 0 and 10°. 相似文献
96.
This paper reports the theoretical and experimental study performed on Hall mobility and free carrier Faraday rotation in a degenerate n-GaSb sample in the temperature range 77–300K. Following relaxation time approximation the mobility is estimated separately for the Γ- and L-valley taking into account the scattering of electrons due to ionised impurities, space charge, polar optical phonons, deformation potential, intervalley acoustic and optical phonons. The effective mobility is calculated considering a two valley model, degeneracy and non-parabolicity of the Γ-valley, and compared with these experimental results. Microwave Faraday rotation data at 77 and 300K is analysed generalising the d.c. magneto-conductivity tensor components as derived by Bordure and Savelli to the high frequency, and is used to confirm the scattering mechanisms and band parameters used in the analysis of d.c. galvanomagnetic results. 相似文献
97.
We report on a new random laser phenomenon that gives rise to narrow emission modes without requiring optical cavities. Sharp emission peaks are observed experimentally over a broad range of scattering strengths and analyzed in numerical calculations. We find that the introduction of exponential gain in a multiple light scattering process strongly increases the importance of very long light paths. Such long paths are rare and often neglected in passive disordered materials but we show that they can dominate the emission spectrum from an amplifying disordered system. 相似文献
98.
The unsteady dispersion of a solute, when the fluid is driven through a curved channel with absorbing walls by an imposed
pulsatile pressure gradient, is studied using the method of moments. The study examines the effect of oscillatory Reynolds
number, amplitude/frequency of the pressure pulsation and boundary absorption on the longitudinal dispersion. The methodology
involves a set of unsteady integral moment equations obtained by applying the Aris-Barton method of moments on the convective-diffusion
equation for a curved channel. Central moments are obtained from the moment equations which are solved by a finite-difference
implicit scheme. The effect of curvature and boundary absorption on the effective dispersion coefficient from the initial
to the stationary stage of the oscillatory flow is studied. Amplitude of the effective dispersion coefficient is found to
increase with curvature and decrease with frequency of the pressure pulsation. For large Peclet number and Schmidt number,
the amplitude of the dispersion coefficient can be 1.6 times that in a straight channel at large times. Also, for large times,
the amplitude of the dispersion coefficient is twice the amplitude of the dispersion coefficient as α, the frequency parameter
changes from 0.5 to 1.0. The axial distributions of mean concentration are determined from the first four central moments
by using the Hermite polynomial representation. The effect of curvature is to delay the stationary state and also the approach
to normality of the concentration distribution. The study has importance in understanding the spreading of pollutants in tidal
basins and natural current fields. 相似文献
99.
100.