I. In a special form of micro gas analysis apparatus the following methods may be used to obtain quantitative separations. Carbon dioxide can be removed at 70°C. by absorption in a mixture of sodium, potassium, and lithium hydroxides. Hydrogen, in the presence of carbon monoxide and methane, can be removed by diffusion through a palladium tube at 325°C; no irregularities occur at this temperature. Carbon monoxide is quantiatively oxidized by a mixture of silver oxide and hopcalite at room temperature. Acetylene is removed by condensation in liquid air. II. The surface of an activated carbon may be oxidized by water at room temperature. The reaction produces at least 1.92 micromols of hydrogen per gram of carbon. An equilibrium is established between the hydrogen, water, and the surface complex, after relatively long periods of time. The nature of the complex is not indicated. / Science, Faculty of / Chemistry, Department of / Graduate

A new apparatus for the determination of adsorption isotherms is described. The chief feature of this apparatus is that the gas under investigation is allowed to leak slowly, at a known rate, into the adsorbent. The rate at which the pressure increases in the system is recorded. From this data the amount of gas adsorbed by the solid can be calculated and with the measured pressure can be plotted as an adsorption isotherm. The adsorption of carbon dioxide on charcoal has been studied by the use of this apparatus. The reported presence of discontinuities in this adsorption isotherm has not been confirmed. / Science, Faculty of / Chemistry, Department of / Graduate

Equations of change for the various hydrodynamic densities are derived for a dilute gas with degenerate internal states. To obtain a consistent set of hydrodynamic equations it is necessary to expand the collision term of the usual Waldmann-Snider Boltzmann equation (W-S equation) in position gradients of the distribution function [formula omitted]. In particular, the extension of the W-S equation to terms "linear" in the position gradients of [formula omitted] yields the correct form for the equation of change for the internal angular momentum density. Specifically, the production term in this equation of change is t he antisymmetric part of the pressure tensor, which is in accord with a hydrodynamic derivation. In addition, equations of change for the mass density, linear momentum density, and total energy density are also obtained. These results are shown to be similar to equations of change derived via a density-operator technique. Unfortunately, this " linear" extension of the W-S equation does not give a closed set of equations of change. However, a consistent set of equations is obtained if a restriction is placed on the form of the extended W-S equation. / Science, Faculty of / Chemistry, Department of / Graduate

The profiles of the He I lines with forbidden components in plasmas with electron densities below 10¹⁵ electrons per cc. are of astro-physical interest. A pulsed-arc plasma device has been constructed and operated at such initial conditions that in the afterglow (i.e. up to 200 μsec after breakdown), the steadily decreasing electron density passes through the range of interest. The plasma was observed end-on with a monochromator at a wavelength near 4471 angstroms for each discharge, and the intensity recorded as a functions of time. Good shot-to-shot reproducibility of the plasma permitted the line profile to be reconstructed for different times by repeating the measurements at different wavelengths spanning the line. The profile of He I 4471 has been measured for 10¹⁵ cm ̄³ and agreement has been found with the results of Burgess and Cairns (1971) and recent calculations of Barnard and Cooper (to be published). / Science, Faculty of / Physics and Astronomy, Department of / Graduate

A single Fe³⁺ species has been introduced into Linde L zeolite and is identified as an iron oxyhydroxide from its Mössbauer relaxation properties. The effects of N₂, CO₂ and C₂H₆ on the ferric species and on the bulk behaviour of the sample are observed by Mössbauer Spectroscopy and adsorption studies under outgassing conditions. The ferric oxyhydroxide initially blocks the pores to gas adsorption but reducing it to Fe⁰ at 943⁰ K and reoxidizing it to α-Fe₂0₃ in air at 773⁰ K frees the pores. The bulk α-Fe₂0₃ is concluded to lie on the external zeolite surface. / Science, Faculty of / Chemistry, Department of / Graduate

This thesis is concerned mainly with developing accurate microwave methods for determining electron-density distributions in transient plasma columns. Two new methods have been developed and these have been evaluated by comparing with other methods. The first is a microwave refraction technique which depends on multiple reflections of an obliquely-incident microwave beam between the plasma critical layer and the walls of the discharge tube. It offers several advantages over previous techniques using microwave refraction; it is simpler and faster to implement, and yields accurate and more reliable results. Several methods for reconstructing profiles from refraction data are described. The second method depends on reflection measurements at normal incidence, and is suitable for plasmas in which the maximum plasma frequency is greater than the applied frequency. This method is based on measuring the rate of change in phase of the reflected signal due to Doppler shift in frequency produced by motion of the plasma critical layer. It has the advantage that the required data can be obtained from relative phase measurements which are less subject to experimental error than absolute phase measurements. Several methods of reconstructing profiles are developed. Approximate profiles can be determined from data at two frequencies only, while more detailed profiles involve applying a step-by-step procedure to data obtained at several frequencies. The sensitivity of the method to certain experimental errors is investigated and the validity of ray theory in the normal-incidence application is examined. A few related measurements were carried out in order to examine the validity of some assumptions made in connection with the microwave methods for determining profiles. The effect of polarization, the effect of altering the discharge-current waveform, and the possibility of a density gradient in the axial direction were investigated. Iangmuir double probes were used in a few cases to obtain an independent measurement of the electron-density distribution. Using the microwave refraction technique, extensive measurements were carried out in an afterglow plasma for various discharge conditions. A few interesting characteristics were observed, and a possible reason for the observed shape of electron-density profiles is suggested. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Using modern signal averaging techniques, the proton and fluorine spin-lattice relaxation time T₁ has been measured in CH₄, CF₄, CHF₃, CH₃F, and CF₃Cl gases at low densities and 297°K. By measuring the dependence of T₁ on density near the characteristic T₁ minimum, we have been able to obtain new information on the spin-rotation interaction coupling constants in CF₄, CHF₃, and CH₃F. The CH₄ system was used to test the validity of this method since the spin-rotation coupling constants are accurately known for CH₄. The correlation function for the spin-rotation interaction was found to be exponential within experimental error for all of the molecules studied. The temperature dependence of the fluorine T₁ in CHF₃, CH₃F, and CF₄ was investigated at higher densities. The proton T₁ in CHF₃ and CH₃F have also been studied in the same density region and at several temperatures. A very striking density dependence of the proton T₁ in these two symmetric-top molecules was discovered. A plot of T₁/ρ versus ρ shows "steps". Steady-state Overhauser effects have been studied in experiments performed at 297°K in both CHF₃ and CH₃F gases to demonstrate the importance of the intra-molecular magnetic dipolar interaction at moderate densities. This interaction in CHF₃ and CH₃F is found to be responsible for the peculiar density dependence of the proton T₁. A phenomenological interpretation of the above proton results was given using a high temperature approximation relaxation theory in which the correlations between the spin-dependent interactions of the different nuclei and the existence of three distinct molecular symmetry species in CX₃Y molecules were properly accounted for. A detailed molecular theory for polyatomic molecules is still needed to extract information on the anisotropic part of the inter-molecular potential. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The investigation of gas-surface interactions has been approached from two different aspects. Firstly, the design and construction of an apparatus to measure low coverage isotherms for argon on evaporated metal films in the region of liquid nitrogen temperature is discussed. Secondly, a detailed analysis of available second and third order gas-solid interaction data has been carried out. It is found that the existing theories for interpreting and calculating three-body forces in physical adsorption systems are incapable of explaining the observed values. / Science, Faculty of / Chemistry, Department of / Graduate

A discussion of probe measurement of the magnetic field in a plasma is presented with particular reference to the perturbation of the magnetic field caused by the probe. A correction procedure is developed to compensate for this perturbation. Using magnetic probes, radial variation of the current density distributions are obtained for an argon plasma in a z-pinch discharge. Initial argon pressures of 100, 250, and 500 μHg are investigated. The current density distributions are determined for 1 μsec intervals between the initiation of the discharge and the occurrence of the first pinch. These current density distributions are compared with photographic observations. The experimental results are discussed in terms of the snowplow model and the shock wave model. Mathematically, the non-linear snowplow equation is solved using an approximation technique which results in analytic solutions. The shock wave equation is solved by a graphical technique. An extension of the shock wave model is proposed for a better understanding of the experimental results. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

A classical gas whose particles interact through a weak long range attraction and a strong short range repulsion is studied. The Liouville equation is solved as an infinite order perturbation expansion. The terms in this series are classified by Prigogine type diagrams according to their order in the ratio of the range of the interaction to the average interparticle distance. It is shown that., provided the range of the short range force is much less than the average interparticle distance which in turn is much less than the range of the long range forces the terms can be grouped into two classes. The one class, represented by chain diagrams, constitutes the significant contributions of the short range interaction; the other, represented by ring diagrams, makes up, apart from a self-consistent field term, the significant contributions from, the long range force. These contributions are summed to yield a kinetic equation. The orders of magnitude of the terms in this equation are compared for various ranges of the parameters of the system. Retaining only the dominant terms then produces a set of eight kinetic equations each of which is valid for a definite range of the parameters of the system. The short-time stability of the system is examined and a criterion for stability obtained. The equilibrium two-particle correlation function and an equation of state are determined, the latter being compared to the Van de Waals equation of state. / Science, Faculty of / Physics and Astronomy, Department of / Graduate