Raman spectra of alkali halides

In this article, we present a comparative study of the Raman spectra of alkali halides in relation to the lattice dynamics ofBorn andRaman. It is shown that the experimentally observed limit of the second-order spectra in almost all the cases can be explained well by the Lyddane-Sachs-Teller relation. It is also seen, while, an explanation of the second-order Raman spectrum of a crystal of diamond or zinc blende structure requires the frequencies from the critical points,W, Γ, X andL inBorn's analysis, the frequencies fromΓ, X andL alone are sufficient and necessary for an interpretation of the same onRaman's model. Some similarities in the determination of the long wave properties of crystals like elastic constants and limiting frequencies of the lattice vibrations in the symmetry directions in both the models are pointed out.     

Fast atom bombardment positive-ion mass spectra of 1,2,2-tris(sulfonyl)hydrazines

Several 1,2,2-tris(sulfonyl)hydrazines, conceived as prodrugs of 1,2-bis(sulfonyl)hydrazines and synthesized as potential antineoplastic and trypanocidal drugs, were analyzed by mass Spectrometry as part of the confirmation of the structure of these compounds. Since these compounds showed activity against several transplanted animal tumors, an understanding of the mass spectral behavior of these agents is important to gain information should clinical trials and metabolic studies be undertaken. In all spectra, protonated molecular ions were observed. Collision activation resulted in considerable fragmentation in the fast atom bombardment spectra. Rearrangement ions formed by elimination of substituted diimides from the middle of the molecule were observed. Other rearrangements involving the alkyl substituent and sulfonyl oxygen also occurred.     

Ultraviolet bands of mercury bromide

The ultraviolet bands of mercury bromide have been excited in uncondensed discharge and photographed with a quartz Littrow spectrograph. The class II system, lying betweenλ 2900 å to 2700 å, suggested byWieland as due to the triatomic molecule, has been studied in detail and ascribed to the diatomic molecule. The bands in the regionλ 2900 å to 2770å have been analysed into two systems which may form the two components of a² II ?² σ electronic transition with a² II interval equal to 969·4 cm^?1. Another system most probably due to² σ?² σ has been observed in the regionλ 2770 to 2720.     

NQR Studies of the chloro(amino)cyclotriphosphazenes,N3P3(NHCH2·CH2NH)Cl4, N3P3(NHBut)4Cl4 and N3P3(NHBut)4Cl2

The frequencies and variable-temperature behaviour of ³⁵Cl nuclear quadrupole resonance in three aminocyclophosphazene derivatives are reported. The observed frequencies and multiplicity are correlated with the disposition of the substituents and the crystal structure. The temperature-dependence data are discussed in the framework of Bayer-Kushida-Brown equations and low-lying torsional (librational) frequencies and their average temperature coefficients are estimated. Brown's parabolic equation provides a good fit to the experimental data. Variable-temperature proton FT-NMR measurements (at 270 MHz) have also been carried out. The results are consistent with the NQR data and indicate the presence of two-site chemical exchange of the -NH protons and hydrogen bonding.     

Free carrier absorption in a ferromagnetic semiconductor below Curie temperature

The free carrier absorption (FCA) in a non-degenerate ferromagnetic semiconductor due to electron-two-magnon scattering is calculated below the Curie temperature, assuming a wide conduction band model. It has been found that in EuO FCA due to two-magnon scattering is proportional to λ^2·1 (wavelength of radiation) and it has been noticed that for high conductivity samples, explanation of FCA requires the inclusion of ionized impurity scattering of electrons besides the two-magnon process.     

Some observations concerning the direct titration of nitrite with cerium(IV)

Direct titration of nitrite with cerium (IV), with ferroin as indicator, is shown to give satisfactory results if the acidity is kept between 0.033 and 0.055M at the end-point. Loss of nitrous acid owing to volatilization and decomposition is discussed. From 10 to 60 mg of sodium nitrite can be estimated with a standard deviation of 5 mug and an average error of 0.2%.