Reexamination of the I2 spectrum near the B(3Π0u+) state dissociation limit

The disagreement of Danyluk and King's (Chem. Phys.25, 343 (1977)) rotational constants for levels lying near the dissociation limit of B-state I₂ with the mechanical behavior predicted by near-dissociation theory is investigated. The discrepancies are shown to be much too large to be explained by either the neglect of centrifugal distortion effects in the original analysis or by rotational or spin-rotation coupling to a nearby repulsive 1_u state. These differences are therefore attributed to experimental error, a conclusion which is confirmed by more recent experimental results. A reanalysis of the best available data for levels near the dissociation limit of B-state I₂ then yields improved values for the B-state dissociation limit $\text{D}$ = 20 043.16 (±0.02) cm^?1 of the vibrational index at dissociation v_$\text{D}$ = 87.32 (±0.04) and of the long-range potential constant $\text{C}{}_5\text{= 2.88 (±0.03) × 10}{}^5\text{cm}{}^{\mathrm{?1}}\text{A}\text{?}{}^5$. This in turn implies a slightly improved ground-state dissociation energy of $\text{D}$₀ = 12 440.18 (±0.02) cm^?1.     

一致可逆性质与(ω)性质的判定

利用算子的一致可逆性质,定义了一个新的谱集,分别给出了有界线性算子满足(ω)性质的充分条件和必要条件,并在此基础上得到算子与其算子演算满足(ω)性质的判定条件。     

Visible Infra-red Double Extinction Measurements in Densely Laden Media,New Progress

This paper describes new progress obtained with an optical technique called V.I.D.E. (Visible Infra-red Double Extinction) which simultaneously measures mean particle size in the range of 10–120 μm and mean number density in densely laden media (up to 0.1% volume fraction). The underlying theory, taking account of multiple light scattering, is recalled. Simultaneous size and concentration measurements are obtained by simultaneously recording transmittances of the medium at two well chosen wavelengths. Experimental results for suspensions of glass particles in air, are described and discussed. The size of particles given by the technique agrees with that given by optical microscopy and Malvern diffractometry. The V.I.D.E. technique is shown to be very suitable to investigate dense media whose optical thickness is up to nine and for which other techniques fail.     

Polymer-dispersed liquid crystals: Preparation, operation and application

Liquid crystal-polymer composites have been widely studied in the last ten years, both because of potential applications and to improve our understanding of the behavioural mechanisms involved. Although it cannot be exhaustive, this review describes recent advances in the field of liquid crystal-polymer composites. The preparation techniques as well as the operating principle and various applications of these materials are covered.     

The New Phosphates Ln1/3Zr2(PO4)3 (Ln = Rare Earth)

The new phases Ln_1/3 Zr₂(PO₄)₃ (Ln = Rare Earth) crystallize with the Nasicon-type structure. The rare earth is located in the usually labeled M₁ site with rather ionic Ln -O bonds. The ceramics resulting from the decomposition of these phosphates have been characterized in the case of lanthanum and europium. They exhibit a very low thermal expansion between room temperature and 1340°C.     

Constantes de couplage de vinylallènes

In order to define the influence of an allenic type conjugation, the NMR spectra of vinylallene and of some of its methyl derivatives are analysed The signs of the coupling constants are also determined. These compounds are characterised by a planar s-trans structure of the two noncumulated double bonds. A discussion of the parameters, and especially of the methyl replacement effects, evidences the importance of the π type contributions. The theoretical calculations of the coupling constants by the methods of finite perturbation CNDO and INDO corroborate this interpretation.     

Q β measurements and mass excess values for neutron deficient isotopes nearN∼Z∼40

Neutron deficient isotopes of⁸⁶Nb,⁸⁷Nb,⁸⁷Mo and⁸⁸Mo have been produced and identified. Their total decay positron energy have been measured and used to deduce mass excesses.