Pressure broadened line widths of BrCN in the microwave region

The line widths of cyanogen bromide (BrCN) have been measured at room temperature (305 K) by using a double modulation microwave spectrograph. The self-broadening of two quadrupole hyperfine lines of the transition J = 3 → 4 has been measured. The foreign gas broadening by OCS, CO₂, N₂, CH₃CN, CH₃I, HCHO and CH₃CHO molecules has been measured only for the intense line at 32·957 GHz. These measured line widths have been compared with the calculated line widths using Anderson [6] as well as Murphy and Boggs [8] theories of pressure broadening.     

Spectra of semi-regular polytopes

We compute the spectra of the adjacency matrices of the semi-regular polytopes. A few different techniques are employed: the most sophisticated, which relates the 1-skeleton of the polytope to a Cayley graph, is based on methods akin to those of Lovász and Babai ([L], [B]). It turns out that the algebraic degree of the eigenvalues is at most 5, achieved at two 3-dimensional solids.Dedicated to the memory of R. MañéResearch supported by MCT and CNPq, Brazil.     

Kinetics and mechanism of the ruthenium(III)-catalysed oxidation of aminoalcohols by cerium(IV) in a sulphuric acid medium

Summary The kinetics of the ruthenium(III)-catalysed oxidation of primary (viz. 2-aminoethanol and 3-aminopropanol) secondary (diethanolamine) and tertiary aminoalcohols (triethanolamine) by cerium(IV) in a sulphuric acid medium have been studied spectrophotometrically. The reactions exhibit a zero-order rate-dependence with respect to the oxidant and first-order rate-dependence with respect to each of the substrate and catalyst. First order dependence of rate in sulphuric acid is found for primary aminoalcohols. A suitable mechanism, consistent with the observed kinetic data, is proposed.     

Characterization of glass surfaces by electron spectroscopy

Commercial glasses typically consist of many metal oxides and the surface composition of a glass article can be very different from that of its interior due to vaporization, surface migration, etc., during fabrication. At the same time the chemical make-up of the surface is extremely important in any commercial application, directly affecting the strength and durability of the product. Analytical techniques capable of examining the surface composition have been limited, however, and classical methods of chemical analysis have never been able to supply the desired information. This paper contains a review of analytical procedures that have been used for glass surface analysis and explores the potential of several recently developed techniques. These include the Electron Microprobe, Electron Spectroscopy for Chemical Analysis (ESCA), Auger Electron Spectroscopy, Ion Scattering Spectroscopy and Secondary Ion Mass Analysis. The use of Electron Spectroscopy in the study of glass compositions common to the glass fiber industry will be explored in depth.     

PHOTOFRAGMENTATION OF PHOTOTOXIC DIBENZOCYCLOHEPTADIENE ANTIDEPRESSANTS

Abstract— Abstract-The products of photochemical reaction of a family of phototoxic tricyclic antidepressants have been determined, both in the presence and absence of oxygen. Under all conditions photofrag-mentation of the phototoxic compounds is an important reaction-in some cases it is virtually the only photoreaction observed. The mechanism of photoreaction appears to involve excited state electron transfer from the side chain to give a reactive exciplex, which fragments via both radical and ionic pathways. These reactive intermediates are likely to contribute to the in vivo phototoxicity of these compounds.     

Electric-field mapping of some anions and cations of adenine and guanine

Electric-field maps of certain anions and cations of adenine and guanine have been studied. The results are compared with those of neutral adenine and guanine. In all cases, the geometries were fully optimized using the MNDO molecular orbital method and the fields were computed using Mulliken charges. Reactivities and hydrogen-bonding pattern predicted by electric fields, including those of cations, are in satisfactory agreement with experiment. © 1993 John Wiley & Sons, Inc.     

Compton profile study of α-manganese

The results of a Compton profile study on polycrystallineα-Mn are reported. Our measurement are compared with theoretical results computed for different 3d-4s electron configurations within the RFA model. Best agreement between the measured and calculated values is found for 3d ^5·44s ^1·6 configuration. Theoretical Compton profile ofγ-Mn calculated using the same procedure is close to that for bcc phase with similar electron configurations.     

Estimation of silica

5,6-Benzoquinaldine and 8-hydroxyquinaldine have been used as organic bases for the quantitative precipitation of silica as silicomolybdic salts of the bases under suitable conditions of acidity. The salts, being stable and non-hygroscopic, may be directly weighed after drying at 110–150° C or alternatively may be ignited at 550° C with free access of air to silicomolybdic anhydride.     

The rotational and vibrational spectra of 1,3-dithiole- 2-one

Microwave spectra of 1,3-dithiole-2-one show that the molecule has a planar equilibrium conformation. IR and Raman spectra are analysed to give the normal modes of vibration.