Structures and Spectral Characteristics of Silylborane,Silylaluminum Hydride,Silylphosphine, and Silyl Mercaptan

The vibrational frequencies of several silanes H₃SiX (X=BH₂, AlH₂, PH₂ and SH) are determined. The infrared and Raman spectra are plotted. Several scale procedures were use to improve the theoretical spectra. The geometric parameters in the planar, staggered and eclipsed structures of these species are fully optimized and compared with ab initio calculations. Basis set effects on the calculated structures are discussed. A few thermodynamic parameters, net atomic charges, dipole moment and energy are also computed.     

Some Aspects of Intra- and Inter-Molecular Reactions of Siliconium Ions in the Vapor Phase

Intramolecular rearrangement processes in the mass spectra of trimethylsilyl derivatives of hydroxy steroids are discussed in terms of the reaction of a siliconium center and a heteroatom. The reaction is shown to be stereospecific. The reactivity of siliconium cations also results in the occurrence of intermolecular reactions under electron impact ionization conditions. Tetramethylsilane is used as a precursor for the production of siliconium ions and examples of chemical ionization mass spectra employing this reagent are shown.     

Defect-related relaxation processes in irradiated rare gas solids

Electronic and atomic relaxation processes in preirradiated solid Ar doped with N 2 were studied with a focus on the role of radiative electronic transitions in relaxation cascades. Combining methods of activation spectroscopy - thermally stimulated and photon-stimulated exoelectron emission, a new channel of relaxation induced by photon emission from metastable N atoms was detected. It was shown that in insulating materials with a wide conduction band photons of visible range can release electrons from both kinds of traps - shallow (lattice defects) and deep thermally disconnected ones. Correlation in the charge recombination reaction yield and the yield of low temperature desorption - important relaxation channel in a preirradiated solid - clearly demonstrates interconnection between atomic and electronic processes of relaxation.     

IR Absorption and Raman spectroscopic study of reentrant-nematic liquid crystalline N-[4-(4-Octyloxy-benzoyloxy) Benzylidene]-4-Cyanoaniline (OBBC)

Abstract

The IR absorption and Raman scattering of OBBC have been investigated in the solid, ReN, SmA and nematic phases. The intensity of the 2229 cm^?1 band assigned to the C[tbnd]N stretching mode decreases with increasing temperature in the reentrant nematic phase; this is attributed to a change in the overlap of the molecules. While the IR bands at 1728 and 841 cm^?1 also show a remarkable temperature dependence, Raman bands do not show significant temperature dependence in the liquid-crystal phases.     

Interpretation of Polarized Absorption and Emission Spectra of Molecules Incorporated in Stretched Polymer Films

Different methods for the interpretation of linear dichroic spectra of molecules incorporated in uniaxial matrices are discussed. A method based on the combination of both polarized absorption and emission measurements is described for the resolution of absorption and emission spectra into their different polarized components, and for the investigation of molecular distributions in the oriented matrix. The distributions of some planar molecules of different shapes incorporated in stretched polyethylene films are presented.     

Trace Impurities in Phosphor Grade CaWO4 - A D.C. Arc Spectrographic Method

Abstract

A simple d.c. are emission spectrographic method is described for the determination of 12 trace impurities in phosphor grade CaWO₄ in the range 5 to 250 ppm. A charge of 25 mgs containing sample mixed with graphite in the ratio 1:3 is excited in a 10 amp d.c. arc. Scandium is used as the internal standard. The precision of the method is ± 15%. Detailed discussion on the selection of the final parameters has been given with supporting data.     

Characterisation of PDO olive oil Chianti Classico by non-selective (UV–visible,NIR and MIR spectroscopy) and selective (fatty acid composition) analytical techniques

An authentication study of the Italian PDO (protected designation of origin) extra virgin olive oil Chianti Classico was performed; UV–visible (UV–vis), Near-Infrared (NIR) and Mid-Infrared (MIR) spectroscopies were applied to a set of samples representative of the whole Chianti Classico production area.     

New measurements and analysis of the far-infrared spectrum of CH2DOH in the lowest torsional vibrational state (e0)

In this work the far infrared (FIR) absorption spectrum has been measured for the asymmetrically mono deuterated Methanol (CH₂DOH) species in the wavenumber range of 15–1200 cm⁻¹ better accuracy and signal/noise ratio than known before. Assignments have been made for b-type transitions in the lowest lying torsional vibrational state trans-(e₀) for a wide range of rotational angular momentum. The assignments have been rigorously confirmed by the residual loop defect methods. The ^rR–branch wavenumbers are analyzed by the usual state dependent expansion parameters and the Q-Branch origins. These origins have been used to calculate the torsional and torsional-rotation interaction contributions. These findings are in good agreement with predicted from the Hamiltonian model described in recent publications. A large number of assignments have also been made in the millimeter wave spectrum recorded earlier and thereby evaluated the asymmetry splitting parameters for 4 different axial rotational angular momentum quantum numbers. The analysis and interpretation of the spectra are reported. New assignments for about 260 transitions are included the text and a catalog of about 1500 transitions belonging to the e₀ species is prepared (Appendix 1) and is made available through the open server in “Research Gate” and will be freely available to others.     

Analysis of Urinary Calculi Containing Triamterene. Presence of A Glucuronic Metabolite.

Abstract

Urinary calculi containing triamterene were described since 1979. We have studied calculi, obtained from an anuric patient, by surgery. This paper describes the advanced techniques that were used, such as infrared spectroscopy, nuclear magnetic resonance, mass spectrometry associated with thin-layer chromatography or gas chromatography, to show the presence of unusual compounds. Six metabolites are found, among them pure triamterene (96%), hydroxy-triamterene, and a particular metabolite containing glucuronic acid.