The fractional ionic character of alkali and silver halide crystals

The fractional ionic character of alkali and silver halide crystals is defined in terms of the deviations from the additivity rule for polarizabilities of ions. The electronic polarizabilities of ions are calculated using an empirical relationship according to which the electronic polarizability of an ion can be assumed to be directly proportional to the cube of its radius. The calculated ionicities indicate that the alkali halides are nearly or more than 90% ionic and silver halides are much less ionic which is also evident from the Phillips ionicity scale.     

Non-linear vibrations of beams and membranes

Summary Non-linear vibrations of beams and membranes are considered using a modified perturbation method based on the Linstedt-Poincare technique, which avoids the secular terms.

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Zusammenfassung Mittels einer abgeänderten Störungsmethode, welche auf der Linstedt-Poincaré-Technik basiert und die säkularen Glieder vermeidet, werden nichtlineare Schwingungen von Trägern und Membranen untersucht.

     

Analysis of the photoelastic effect in ionic crystals

An analysis of the photoelastic effect in ionic crystals has been presented within the framework of Clausius-Mossotti theory of the dielectric constant. The values of the strain derivative of the electronic dielectric constant have been calculated in alkali halides and MgO crystals by taking into account the variation of electronic polarizabilities with compressive stress. The results obtained are found closer to the experimental values. The photoelastic behaviour of MgO crystal is predicted to be of opposite nature to that of alkali halides, in conformity with the experimental observations.     

High-resolution infrared spectrum and rovibrational analysis of the ν3 fundamental of diazirine,H213CN2

The high-resolution infrared spectrum of ¹³C-diazirine was recorded using a high-information Fourier transform spectrometer with a resolution of 0.0054 cm^?1. The rovibrational structure of the ν₃ fundamental at 1458.1884 cm^?1, which is an A-type parallel band (¹³CH₂ deformation) was assigned and analyzed with extensive use of modern methods of spectrum simulation. The rovibrational assignment and the molecular constants determined for the excited vibrational level of this band are given.     

A comparative study of the properties of the liquid crystalline compounds 5O.5 and 5O.6 in solid, solution and thin film forms by laser Raman spectroscopy

Raman spectroscopic studies of the liquid crystalline compounds 5O.5 and 5O.6 revealed that the two aromatic rings in the core are in different environments with distorted electron cloud distributions, and the behaviour of each of these rings is independent of the other. Increased chain length results in the development of strain on the molecules. During the SmF-SmB phase transition there is a slight transfer of charge, along with an increase in the freedom of the individual molecules. Our experiments also reveal that the molecules are strained in the crystalline state and adopt some preferred orientations in free-standing films. There is also a tendency towards the elongation of the molecules along the C N linkage in solution for 5O.6. Raman spectra of 5O.6 in free-standing films have shown dramatic changes compared with the spectra recorded in the bulk.     

Author index to volume 43

The effect of an ultrasonic field on the stability of the amorphous alloy Fe₇₈Si₉B₁₁C₂ has been stu spectroscopy. It is found that the response of the alloy to the ultrasonic field depends upon the temperature at which it is exposed to ultrasonics. While at room temperature ultrasonic have no detectable effect on the stability of the alloy, at elevated temperature it markedly enhances the crystallization process. The possible cause of the observed effect has been discussed.     

The C1Πu-X1Σg+ fluorescence of Li2 excited by ultraviolet lines of an argon ion laser

The fluorescence spectra of ⁷Li₂ and ⁶Li₂ excited by an argon ion (3511 Å) laser are analyzed. No fluorescence was observed for 3514- or 3638-Å excitation or for ⁶Li⁷Li. For the C¹Π_u-X¹Σ_g⁺ electronic transition, the spectrum of ⁷Li₂ shows R and P doublets for 0 ≤ v″ ≤ 6 and that of ⁶Li₂ consists of Q lines for 0 ≤ v″ ≤ 11. Through the assignments of these lines (a) Hsu's (Ph.D. thesis, Fordham University, 1974, unpublished) molecular constants for C state have been verified, (b) the reliability of C- and X-state constants for ⁶Li₂ derived from those of ⁷Li₂ through mass-reduced scaling has been verified, and (c) the transition moment for the C-X transition of Li₂ has been shown by comparison of the observed and calculated intensities to be roughly independent of internuclear distance in the region near R_e for the C state.     

Spectrophotometric determination of primary aromatic amines with 4-N-methylaminophenol and 2-iodylbenzoate

2-Iodylbenzoate is proposed as an oxidimetric agent, in the presence of 4-N-methylaminophenol, for the spectrophotometric determination of primary aromatic amines. The purple-red product absorbs maximally at 525 nm and Beer's law is obeyed over a range corresponding to 4-32 mug/ml amine in the final solution. In contrast to dichromate or N-bromosuccinimide, previously used as the oxidant, 2-iodylbenzoate avoids errors arising from too large an excess of the oxidant, instability of the coupling intermediate, and the oxidation of the amine.