Orientador : Claudio Airoldi / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-07-14T01:30:48Z (GMT). No. of bitstreams: 1 Oliveira_SeverinoFranciscode_D.pdf: 5160763 bytes, checksum: 331e79df22cb8f405ba7885830d6d3e4 (MD5) Previous issue date: 1990 / Doutorado

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The chemistry of co-ordination compounds in general has played an important role in the development of the modern theory of valency, but the properties of complex salts between chromium and organic compounds containing carboxyl and amino- groups are of additional interest because of their bearing on the theory of certain technological processes such as chromium plating and, in particular, chrome-tanning. Owing to the rapid development of valence theory over the last two decades the technological chemist finds himself at a disadvantage vis-a-vis his academic counterpart in attempting to interpret the results of researches relating to these compounds as he must rely on the less powerful "classical" approach to his problems. Hence the need was felt for a brief survey of modern concepts of valency in terms of wave mechanics. For a more extended study the reader may consult the appropriate references and text books.

In this work physical and analytical methods have been used to investigate the potassium salts of certain dioxalato chromium (III) complexes. The solid potassium salts of the trioxalatochromiate and the cis and trans dioxalatodiaquochromiates together with a salt corresponding to potassium dioxalatosulphatoaquochromiate were prepared. The mono- and dihydroxo derivatives of the cis and trans dioxalatochromiates were also obtained in aqueous solution. The methods of preparation and analysis used are described. Spectrophotometric absorption curves obtained on solutions of these salts using a Beckman Spectrophotometer are in agreement with results of previous workers, and the new absorption curve obtained from a solution of the solid cis dioxalatodiaquochromia salt shows that it is pure and gives additional proof of the completeness of the trans - cis isomerisation. Summary, p. i.

Experiments are described on the possibility of developing a gas luminescence chamber for the observation of particle tracks. A brief review of devices currently available for obtaining ionizing particle tracks, particularly those capable of time resolutions in the microsecond region, is included. Attempts were made to detect scintillations in several gas and vapour mixtures. For some gas mixtures the possibility of using ionizing radiation to initiate a light producing chain reaction was investigated. These experiments were performed in the temperature range from 25 to 220° centigrade. Results obtained were not of such a nature to encourage further work towards the development of a gas luminescence chamber. As a background of non-radiation induced photon emission was observed for several reactions, it is possible that the methods employed in the experiment may be adopted to measure the onset and rate of some chemical reactions. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The conductivities of the homologous series from tetra-methyl to tetra-n-amyl of the normal tetraalkylammonium iodides and bromides in acetonitrile at 25° C have been determined. The concentrations studied ranged from 0.006 to 0.00003 moles per litre. These salts are fairly strong electrolytes in acetonitrile. The iodides have higher conductivities and are more highly dissociated than the corresponding bromides. The conductivities decrease with increasing size of the alkyl group and the degrees of dissociation show a corresponding increase. There is a relatively large difference between the tetramethyl and tetraethyl ions and then smaller, fairly regular differences in going from tetraethyl to tetra-n-amyl. The limiting equivalent conductivities have been calculated by the methods of Shedlovsky and Fuoss. It is shown that the dissociation constants calculated by the method of Shedlovsky and those calculated by the method of Fuoss are not related in the manner predicted by these authors. Ionic conductances have been calculated by assuming that Walden's rule applies to the tetra-n-butylammonium ion. A comparison of ionic resistances in some organic solvents shows that the quaternary ammonium ions have little tendency to interact with solvent molecules. / Science, Faculty of / Chemistry, Department of / Graduate

The ion beam transmission efficiency of the ion source is an important factor in determining the sensitivity of a mass spectrometer. Vauthier (1955) has shown for a simple source that the transmission efficiency is very low. The present thesis examines the transmission efficiency of a more complex source. The first part of the thesis deals with the ion optical properties of a multiple slit ion source. The region of ion withdrawal has been sketched by computing the ion trajectories passing through the exit slit. It was found that for the more complex source the region of ion withdrawal is also much smaller than the total ionization space. It is not practical to confine the ionization region to the small volume from which ions are withdrawn. The effect of a source magnetic field has been taken into account. The perturbation of the trajectory due to the field is small, and therefore the mass discrimination due to the source magnetic field is imperceptible for heavy ions unless the field is of the order of a few webers/m². The multiple slit ion source produces a divergent ion beam, only a small fraction of which penetrates the exit slit. Obviously a system producing a beam converging at the exit slit to a narrow parallel ribbon will be most efficient. In order to devise such a system a theory of the inverse problem of particle motion is developed in the second part of the thesis. A procedure was found to determine a potential distribution required to guide a group of particles along a set of prescribed paths. There are two important limitations to the choice of paths: (a) there are certain paths which are not complete; that is a particle following such a path is turned back at certain points which we call mirror points. (b) The particles which do not satisfy the initial conditions of uniform energy and direction may deviate considerably from their projected paths leading to what we have called an unstable situation. Fortunately the complete paths are stable, and the incomplete paths are unstable. Of the two types of convergent paths studied, namely, exponentially decreasing and damped oscillatory paths, the system of damped oscillatory paths is stable. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

By using a pair of large Nal spectrometers in a coincidence configuration we have observed the charge exchange of stopped π⁻ in deuterium π⁻ + d → 2n + π°. We have measured the branching ratio of this reaction [equation omitted] and find R = (1.45 ± 0.19) x 10⁻⁴. This measurement is the first observation of pion charge exchange at rest in deuterium and represents an increase in sensitivity of a factor of 40 over previous measurements. The measured value of R agrees well with the recent theoretical result of Beder(1.39 x 10⁻⁴ ≤ R ≤ 1.59 x 10⁻⁴). / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This thesis examines the operation and control of a radiofrequency ion source.

Previous work on crystal field aspects of the vibrational spectra of metal β-ketoenolates has been extended here to metal tropolonate complexes. The crystal field trends have been used to assist in the assignment of metal sensitive vibrations to the transition metal tropolonate complexes. A study has been made of the effects of spin state and Jahn-Teller distortion on the vibrational spectra of the metal tropolonates. Of particular interest is the octahedral divalent metal tropolonate adducts, where the distortion of the copper complex is small, and the metal 2-thiotroponates where the Jahn-Teller- distortion is absent. The spectra of the lanthanide tropolonates are of interest, as a plot of the metal sensitive vibrations show the 'double-humped' curve indicating that crystal field effects are present in the lanthanide ions. This has not previously been shown. Further, from the vibrational spectra of the various lanthanide tropolonates, various conclusions are made regarding structure. The non-transition metal tropolonates provide a system devoid of crystal field effects and afford the opportunity to investigate the influence of other factors on the vibrational spectra. Of interest is the strong influence of the ionic radius and ionization potential on the metal sensitive vibrations and the remarkably small influence of the mass of the metal ion on these vibrations. Although the vibrational spectra of complexes of ethylenediamine and N- substituted ethylenediamines were studied, difficulty with, assignment of the metal sensitive vibrations and the complicating influence of substituents on the spectra, prevents any observations made, from being conclusive.