523 results for 1970, Doctoral

  • The spectra of transition-metal ions in solids

    Johnstone, I.W. (1975)

    Doctoral thesis
    University of Canterbury Library

    The results of an investigation of the Raman and infrared spectra of cobaltous ions in cadmium-chloride, cadmium-bromide, and manganese-chloride, and of cobalt-chloride are presented. The cobalt ions substitute for the cation in these crystals and experience a trigonal crystal-field which splits the lowest ⁴T₁g (⁴F) cubic-field term into six Kramers doublets with energies in the range 0-1200 cm⁻¹. The Raman spectra, measured as a function of temperature and of cobalt concentration show all five single ion electronic transitions together with several lines due to cobalt ion pairs. The infrared spectra comprise both magnetic-dipole allowed electronic transitions and electric-dipole allowed vibronic lines and bands. They confirm the identity of the electronic transitions seen by Raman scattering and also yield information concerning the lattice modes of the host and the possible interactions within cobalt ion pairs. The strong field matrices of the trigonal crystal-field and Zeeman interactions are calculated for the d³ (d⁷) configuration and quantitatively explain the experimental data. The crystal-field analysis provides single ion wavefunctions for further calculations which successfully explain the spectra of antiferromagnetic CoCl₂ and exchange coupled colbalt pairs in CdCl₂ (Co²⁺) and CdBr₂ (Co²⁺). A preliminary investigation of the infrared absorption of an oxygen-induced impurity site in CdCl₂-type crystals is also presented.

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  • Upper atmospheric studies using radio meteors

    Wilkinson, Philip James (1973)

    Doctoral thesis
    University of Canterbury Library

    The atmospheric motions in the 80-110 km height region, and methods of measuring them are discussed. Wind measurements using radio meteor trails are then considered in greater detail and an account is given of the equipment at the field station of the Physics Department of Canterbury at Rolleston near Christchurch, as well as details of the data reduction methods used. An analysis of the errors associated with the collection of data indicates that approximately half the variance in an average of wind velocities observed in a thirty minute period is due to atmospheric variability. Results from the first year's observations suggest that the solar diurnal and semidiurnal tides are of roughly the same magnitude, this magnitude being in agreement with the latitudinal variations observed at other stations.

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  • The group theory of the harmonic oscillator with applications in physics.

    Haskell, T. G. (1972)

    Doctoral thesis
    University of Canterbury Library

    The possibility of the group SU₃ being used in the description of the (d+s)N and (d+s)npm many-electron complexes is examined by symmetrization of the Coulomb Hamiltonian. By dividing the Coulomb interaction into symmetry conserving and symmetry violating terms it is found that while the SU₃ scheme tends to give a better description in the (d+s)N case it shows no improvement over the configurational scheme in the (d+s)npm complex. The scheme is, however, very useful for the calculation of matrix elements of operators normally found in atomic spectroscopy and a complete set of symmetrized , scalar, Hermitian spin-independent two particle operators acting within (d+s)npm configurations is constructed. The radial wavefunctions of the harmonic oscillator are found to form a basis for the representations of the group 0(2,1) in the group scheme Sp(6,R) ⊃ S0(3) x 0(2,1). The operators Tkp = r2k are shown to transform simply under the action of the group generators. The matrix elements of Tkq and a selection rule similar to that of Pasternack and Sternheimer are derived. Finally the rich group structure of the harmonic oscillator is investigated and a dynamical group proposed which contains, as subgroups, the groups Sp(6,R), SU(3), H₄ and the direct product 0(2,1) x S0(3). Some remarks are made about contractions of groups, semidirect and direct products, and the generalization of the method to n-dimensions.

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  • Solid state spectroscopy : rare earth - hybride centres in the alkaline earth fluorides

    Jacobs, I.T. (1971)

    Doctoral thesis
    University of Canterbury Library

    Both the optical and infrared spectra of cerium and praseodymium tri-positive ions in the alkaline earth fluorines have been studied. Various charge compensation mechanisms have been employed including negative hydride, deuteride and tritide ions. For the hydride centres the degenerate local mode lines are resolved into more than one component. These splittings are attributed to electron-phonon interaction effects between the low lying rare earth 4f electronic states and the hydride ion local mode phonons. The 4f-5d electronic transitions of the cerium hydride type centres show large isotope shifts up to 50 cm⁻¹. Only the non-degenerate hydride ion vibration appears in the 4f-5d optical spectra and the vibrational interval is increased from absorption to fluorescence by as much as 15%. Both the isotope and vibronic shifts for the tetragonal cerium sites are attributed to electron-phonon interaction effects. Simple models involving point charges and point dipoles account in a semi-quantitative way for several features of the spectra but fail to account for either the sign or magnitude of the isotope and vibronic shifts.

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  • Upper atmospheric studies : some observations of the south tropical OI airglow phenomenon

    Malcolm, Roger K. (1972)

    Doctoral thesis
    University of Canterbury Library

    An account is presented of a series of observations of the dynamic behaviour of a region of the south tropical airglow·arcs made from Rarotonga (Lat. 21.2° south, long. 159.8° west) with the aid of a large aperture (90 cms), high resolution (½° beamwidth) scanning photometer. The night airglow is found to be strongly disturbed on many nights, characteristically by elliptical areas of lower than normal intensity drifting in an easterly direction. It was possible to associate their passage with the occurrence of 'spread-F' as observed by the Rarotongan ionosonde. An attempt is made to account for the airglow processes; suggestions are made concerning the possible origin of the disturbances; and their presence is examined in the light of the trans-equatorial propagation of V.H.F. signals from Hawaii, as recorded at Rarotonga.

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  • Solid state spectroscopy : the electron paramagnetic resonance spectra of gadolinium anderbium ions in hydrogenated alkaline earth fluoride crystals

    Edgar, A. (1974)

    Doctoral thesis
    University of Canterbury Library

    The Electron Paramagnetic Resonance technique has been used to study alkaline earth fluoride crystals doped with both hydride and gadolinium (or erbium) ions, and the spin Hamiltonian parameters have been determined for the various kinds of charge-compensated rare earth ion site which occur. In particular, two sites of tetragonal symmetry with the structures RE³⁺-FI⁻, RE³⁺-HI⁻ have been examined, and small shifts in the EPR spectra of the latter site have been measured when a deuteride or tritiide ion replaces the hydride ion. A crystal lattice model of point charges and point dipoles at distorted lattice sites predicts a value of the crystal field parameter B₀² for the tetraqonal sites which is only one half of that estimated from the observed spectra, but the model successfully accounts for the larger value of B₀² for the RE³⁺-HI⁻ site compared with the RE³⁺-FI⁻ site on the basis of the larger polarisability of the H⁻ ion. Isotope shifts are interpreted by the electron phonon interaction between the 4f electrons of the rare earth ion and the localised mode of vibration of the light anion. The magnitudes of the shifts, calculated on a point charge/point dipole model, are in good agreement with experiment. The reorientation of the tetragonal Gd³⁺-HI⁻ sites has been examined by EPR line broadening and dielectric loss techniques. No distinct dielectric loss peak corresponding to this site was observed, and it is proposed that it cannot be distinguished from that for Gd³⁺-FI⁻ sites. An interstitialcy model for the reorientation has been investigated and is found to be consistent with this explanation and with the observation of a metastable Gd³⁺-HS⁻-FI⁻ site in u.v. irradiated calcium fluoride.

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  • Some studies of the theory and application of continuous groups in atomic spectroscopy

    Cunningham, M.J. (1971)

    Doctoral thesis
    University of Canterbury Library

    This thesis is concerned with the representation theory of continuous groups both compact and non-compact and its application to atomic spectroscopy. In Chapter I some atomic wavefunctions for equivalent electrons in the group scheme SU2 x (U2l+1 R2l+1 R3) are constructed in terms of electron fermion creation and annihilation operators. The concept of semiconjugacy is defined and shown to reduce the number of states that must be explicitly calculated. The states of the d shell are calculated and tabulated. In Chapter II it is shown how to extract n-body cfp's associated with arbitrary auxiliary quantum numbers from the n-body generalisation of Redmond's formula. The method is applied to give explicit formulae for the squares of one body cfp's of the atomic d-shell. Group theory is applied in Chapter III to extend the quasiparticle formalism developed by Armstrong and Judd to expose the complete group structure of the eigenfunctions of the equivalent electron l shell. A simple method for relating quasiparticle states to determinantal states and for calculating quasiparticle matrix elements is developed. The need for fractional parentage coefficients in calculating these matrix elements is eliminated. In Chapter IV the technique and formalism is extended to describe general mixed configurations. The hydrogen atom is factorised according to the scheme 0(4,2) 0(2,1) x 0(3) in Chapter V and the radial group 0(2,1) studied. It is shown that rkD n/(n+q) , where Da is a dilatation operator, is proportional to a tensor operator in this scheme, allowing a group theoretical study of the radial matrix element rk, including an explanation of the Pasternack and Sternheimer selection rule. The technique is extended in Chapter VI to solve a differential equation directly related to the generalised Kepler equation of Infeld and Hull in an 0(2,1) x 0(3) group scheme. This equation contains as special cases the Schrodinger, Klein-Gordan, and Dirac (two forms) hydrogen atoms. A generalised Pasternack and Sternheimer selection rule exists and some matrix elements can be evaluated group theoretically.

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  • Erwin Strittmatter in reference to the agarian novel of the nineteenth and twentieth centuries

    Gebbie, Ian William (1978)

    Doctoral thesis
    University of Canterbury Library

    This study deals with two aspects of German literature: the agrarian novel from the early nineteenth century to National Socialism, and a comparison of capitalist and socialist ideology, using the works of the DDR author Erwin Strittmatter. In the first part of the thesis, chosen works are analysed with the aim of establishing a pattern of bourgeois idealism and of tracing its development in reference to the changing historical background. The political implications of the nationalist transformation and radicalisation of the conservative agrarian ideology, which grew up as a middle-class reaction to the emergence of modern industrial Germany, are illustrated by the combination of the heroic and the idyllic in fascist literature. The second part deals with the socialist agrarian novel, which is discussed, in the light of Marxist theory, as a departure from the conservative model, and in relation to different political ideals and objectives. Three agrarian novels of Erwin Strittmatter Ochsenkutscher, Tinko and Ole Bienkopp - are examined in detail as the basis for contrast with capitalist doctrine and for observations on the role of literature in the DDR. The concluding chapter illustrates how, in the established East German state of the 1960's, the disregard for the demands of authority, which is a feature of Strittmatter's Ole Bienkopp, indicates a return to the traditional pattern of bourgeois idealism within the confines of socialist morality.

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  • Atmospheric physics : electron density variations in the mesosphere

    Wratt, D.S. (1974)

    Doctoral thesis
    University of Canterbury Library

    The theory of the differential absorption and differential phase experiments is examined, and it is found that the differences in predicted electron densities due to different hypothetical reflection processes are in general no larger than experimental uncertainties. Results of differential absorption and differential phase measurements are compared. It is found that electron densities in the mesosphere above Christchurch can be affected by energetic particle precipitation. Evidence is also found for increases in electron concentration associated with a stratospheric warming, but apart from this there is no clear evidence for stratosphere-ionosphere coupling above Christchurch. Model studies show that much of the variation over time scales of four days or more above Christchurch could be accounted for by vertical transport of nitric oxide. However, other results make it likely that other processes, such as variations in loss rate, are also important.

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  • On invariant means and applications to ergodic theory and harmonic analysis

    Renaud, Peter Francis (1971)

    Doctoral thesis
    University of Canterbury Library

    This thesis is concerned with the existence and properties of invariant means on certain Banach spaces and their applications to ergodic theory and harmonic analysis. The principal results obtained are as follows. Let G denote either a a-compact, unimodular amenable group or a countable, cancellative semigroup realized homomorphically by measure preserving transformations on a measure space (x, S, μ ) via the maps x → xg. Then there exists an increasing sequence {Sn} in G such that for all f ∊ Lp (X), 1 ⩽ p < ∞ the limit [equation here] exists in the mean of order p and almost everywhere. If G is an amenable topological semigroup then it has been shown by H.A. Dye that the ergodic mixing theorem is valid for G. It is proved that the amenability condition can be entirely removed and a mixing theorem is obtained, valid for arbitrary topological semigroups. The idea of an invariant mean can be dualized to invariant means on the von Neumann algebra of a group. The existence and in general non-uniqueness of such means is proved. The group von Neumann algebra is also used to show that a classical theorem of Bochner may be rephrased so as to become valid for arbitrary amenable groups rather than Abelian groups.

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  • Nonrecursive digital image restoration

    McDonnell, M. J. (1975)

    Doctoral thesis
    University of Canterbury Library

    The problem of digitally restoring blurred images is considered. The subject of image restoration is reviewed in detail and a comprehensive notation for image restoration is developed. Degraded images are divided into classes G and S - those which are and are not respectively truncated by their recording frames. It is shown that conventional restoration techniques only work well for images of class S. Restoration techniques for dealing with class G images are presented, as well as improved techniques for dealing with class S images. These new techniques are shown to be both efficient and practical through the use of computer simulations, and through the restoration of optically degraded images. The problem of designing an optimum nonrecursive digital filter array of a given number of elements is solved in both one and two dimensions. It is demonstrated that this new design method is superior to previous techniques. A sampling theory appropriate for deconvolution problems is presented. New sampling functions are introduced, in both one and two dimensions, which overcome the "picket fence" effect associated with the sine sampling function. The concept of a "line-segment-limited" function is defined. It is shown that a pseudo noise level is introduced by the approximation that the point spread function is line-segment-limited. It is this pseudo noise level, and not aliasing errors, that restricts the choice of a sampling rate less than the Nyquist rate. New criteria are presented which allow the choice of a sampling rate considerably less than the Nyquist rate.

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  • Studies on metal complexes of oxo and related ligands

    Hunter, Sally Helena (1970)

    Doctoral thesis
    University of Canterbury Library

    Transition metal complexes of various substituted phosphine oxides and arsine oxides have been studied. The preparation of tertiary phosphine oxide and arsine oxide complexes of cobalt (II) is reported and comparative spectral and magnetic data presented for Me₃PO and Me₃AsO tetrahedral complexes of the type [CoL₄] (ClO₄)₂ and CoL₂x₂ (X= Cl,Br). These results have been compared with those obtained for the analogous Me₃PS and Me₃AsS complexes, and they indicate that higher metal-ligand covalency is achieved in the M-S bond. Evidence for a distinct difference between P-O-M and As-O-M bonding was obtained from a study of electronic spectral band profiles. Ph₂MePO and Ph₂MeAsO form a range of isomorphous five coordinate square pyramidal complexes of composition [ML₄(ClO₄)]ClO₄. Infrared spectral studies indicate that in the copper complexes and [Fe(Ph₂MeAsO)₄(ClO₄)]ClO₄ axial (perchlorate) bonding is weak and M-O(XPh₂Me) bonding is correspondingly stronger. Evidence is presented to show that the corresponding Ph₃PO and Ph₃AsO complexes of the same composition have essentially the same square pyramidal structure. The electronic spectra of the cobalt and nickel perchlorate complexes have been correlated with energy level diagrams for square pyramidal chromophores. A range of five coordinate [ML₅]²+ and [ML₄(ClO₄)]ClO₄ complexes of Me₃PO and Me₃AsO have been prepared. Corresponding arsine oxide and phosphine oxide complexes are isomorphous. The crystal structure of [Ni(Me₃AsO)₅](ClO₄)₂ has been determined and the cation has been found to be a distorted square pyramid. A limited number of complexes of the bidentate ligand, o-phenylene bis (dimethylarsine oxide) (diarsine dioxide), have been prepared. The halide complexes, CoLX₂, are tetrahedral and possibly polymeric. The crystal structure of [Zn(C₆H₄(Me₂AsO)₂)₂](ClO₄)₂ which is isomorphous to the analogous cobalt complex, has been determined. The complex is dimeric, and the zinc atom is at the centre of a trigonal bipyramidal arrangement of oxygen atoms.

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  • Right orders in full linear rings

    O'Meara, Kevin C. (1971)

    Doctoral thesis
    University of Canterbury Library

    The thesis is a study of right orders in a (left) full linear ring Q = HomD(V,V), V a right vector space over a division ring D. Chapter I, as well as summarizing known results needed in the sequel, outlines the method of attack. In particular, it justifies the hypothesis “suppose Q is a (Johnson) right quotient ring of R” which appears frequently in subsequent chapters. One of the principal results in Chapter II is that right orders in full linear rings of countable dimension must be prime rings whereas in the uncountable case this need not be so. In fact, results in Chapter II suggest that a complete description of a right order in Q may be rather difficult if dim QQ is uncountable (here dim MR refers to the uniform dimension of a module MR). Chapter III is a study of intrinsic extensions of prime rings. This study is required by the condition that regular elements of a right order R in Q be units in Q, since this actually implies Q is left intrinsic over R if Q has infinite dimension. The principal result on intrinsic extensions says that if S is a prime ring with zero right singular ideal, but not an integral domain, and if S contains uniform right ideals then S is a right quotient ring of any prime ring over which it is right intrinsic. This result has several interesting corollaries for example, if dim QQ is countable then a right order R in Q must have Q also as a left quotient ring. The main goal of Chapter IV is finding suitable conditions to ensure a ring R will have a full linear ring as its left-flat epimorphic hull. To this end, two conditions are introduced: condition (A) which requires closed right ideals of R to be essential extensions of finitely generated right ideals, and the existence of a “reducing pair” or elements. The latter means a pair (β, γ) for which βR, γR and βr + γr are large right ideals of R. Taken together, these two conditions on a ring R having Q as a right quotient ring imply that for each xϵQ there exists cϵR such that c has a right inverse in Q and xcϵR. Ample evidence is produced to show that reducing pairs for infinite dimensional rings R play a similar role to primeness for finite dimensional R, in so far as determining when R is a right order in Q. An earlier result of Chapter IV says that if R is a prime ring then R is a right order in Q only if R+ socle Q is, that is, in so far as a study of right oders in Q is concerned, we can suppose R contains the socle of Q. The final chapter contains, among other things, two internal characterizations of a right order R n a infinite dimensional full linear ring. One of these says: A ring R is a right order in a left full linear ring of right dimension ϰ≥ϰ₀ if and only if the following conditions are satisfied. (i) R is a (Johnson) irreducible ring containing uniform right ideals and dim RR = ϰ. (ii) The closed right ideals of R are right annihilator ideals and if B is a right annihilator ideal with dim BR = dim RR then B has the form bℓr for some bϵR with br = 0. (iii) R possesses a reducing pair of elements.

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  • Measurements within self-aerated flow on a large spillway

    Cain, Paul (1978)

    Doctoral thesis
    University of Canterbury Library

    Instruments were developed and were used to obtain measurements of the most important flow parameters within self-aerated flows on the spillway of Aviemore dam. Compressibility effects within self-aerated flows are examined. It is shown that Mach numbers as large as 2 will occur in localised aerated regions on large structures. A probe was developed which measured stagnation pressure and air concentration. The compressible nature of self-aerated flows is taken into consideration in formulating a relationship between these measurements and the velocity of the water. This expression is found to overestimate the velocity by about 7% over a wide range of flow conditions. A velocity probe was also developed, based on a cross-correlation technique. This latter probe was the more successful and is recommended for future measurements within self-aerated flows. Profiles of stagnation pressure, air concentration and velocity were measured at each of five positions down the spillway for each of two discharges. These are the most comprehensive and detailed measurements yet obtained on a large structure. The regions of non-aerated, partially aerated and fully aerated flow down a spillway are distinguished. A dimensional analysis is used to indicate the important variables effecting the distribution of air downstream of the point of inception. This forms the basis for plotting the measurements from Aviemore plus the available measurements from laboratory flumes. The shear stress on the spillway surface at Aviemore is calculated from the measurements.

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  • Hydromagnetic waves in a buoyant medium

    Cummack, C. H. (1976)

    Doctoral thesis
    University of Canterbury Library

    Lighthill has suggested that magnetic fields can transform gravity waves into Alfvén waves. The behaviour of gravity waves in an incompressible and infinitely conducting atmosphere is examined so as to check this suggestion. It is found that an upgoing gravity wave is converted to a downgoing Alfvén wave and that this conversion is affected without any introduced atmospheric discontinuity. In the ionosphere dissipation is sufficient, save at very long wavelengths, to inhibit mode conversion but in the solar atmosphere the process may well operate. The energy necessary to heat the solar corona could possibly be supplied by gravity waves when dissipation occurs after the conversion to an Alfvén wave.

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  • An ecological study of Paranephrops planifrons white (Decapoda: Parastacidae) in Lake Rotoiti, North Island

    Devcich, Alan A. (1979)

    Doctoral thesis
    University of Waikato

    The Paranephrops planifrons population in mesotrophic L. Rotoiti consists of 2 bathymetrically and temporally separate breeding groups. Late autumn breeders comprise about 80% of the population, occupy depths mainly above 30 m and at night feed in the littoral zone, where food is 80% more concentrated than elsewhere. Early summer breeders exist mainly below 30 m depth. Utilisation of the whole lake bottom and seasonal changes in food available to the early summer breeders are tentatively given as explanations of this pattern. Crayfish show increased sensitivity to light intensities greater than 150-205 lux and consequently occupy shelters above around 12 m depth. Shelters include any recesses subjected to intensities below this range. This zone accomodates almost the entire juvenile population and ca 10-20% of the adult population. This response to light intensity is believed to be an adaptation promoting avoidance of their main predator, the shag. Nocturnalism is another adaptation reducing losses to predators, including trout. Crayfish at greater depths lie unprotected and inactive by day and ca 70-80% of these adults form a high density band around the lake at a mean annual depth of 19.2±2.8 m. The band has a mean annual vertical depth range of 11.4±2.1 m and densities up to 50 crayfish m⁻². At dusk activity begins in the deepest waters first and crayfish forming the band migrate shorewards, while those above emerge from shelters. Within the hour feeding on detritus mainly, commences amongst the weed beds which extend to 6 m depth. At dawn a downward migration preceeds reformation of the high density band. These dual diel migrations apply almost solely to late autumn breeders and are part of a circadian rhythm, the timing of which is modified by light. Locomotion associated with migratory activity appears to be effected mainly through leg proprioceptors responsive to gravity. Directional orientation at this time and also generally, is inversely related to bottom slope angle. The diel distribution pattern varies seasonally. In summer and autumn the high density band is displaced shorewards by a vertical distance of 3.3 m, to a mean depth of 18.3 m and there is a 4 fold increase in crayfish inhabiting shallow water shelters. This closer association with the main feeding ground is probably an adaptation to meet coincident increases in energy needs. It applies especially to late autumn breeding females, whose period of ovarian development occurs between December and April. Energy requirements appear to be met through food consumed rather than from food stored. Female feeding activity is directly related to temperature but not in males, and prewinter storage is apparently of little importance in both sexes. Hypolimnetic deoxygenation affects early summer breeders mainly and induces a mass migration from the deeper regions to above the 30 m contour by February. Complete recolonisation of these parts follows lake turnover in May. Crayfish occur on all substrate types in approximately equal numbers except very soft muds, which support densities of <0.001 crayfish m⁻².

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  • Studies in peri-naphthalenes

    Leonard, David (1971)

    Doctoral thesis
    University of Canterbury Library

    1,2,3,4,7,8,9,10-Octahydrodicyclohepta[de,ij]naphthalene (17) and 2,3,6,7,8,9-hexahydro-lH-cyclohepta[gh] phenalene (46) have been prepared via benzsuberone (22), the tricyclic ketone 1, 2, 3, 7, 8, 9, 10,10a-octahydrocyclohepta[de]naphthalene (14), and the tetracyclic ketones 1-oxo- 1, 2, 3, 4, 4a, 5, 6, 6a,7, 8, 9, 10-dodecahydrodicyclohepta[de,ij] naphthalene (30) and 1-oxo-2,3,6,7,8,9-hexahydro-lH-cyclohepta[gh]phenalene (45), respectively. 5,6,7,8-Tetrahydrocyclohepta[fg]acenaphthene (57) was also prepared, by an improved method. The dicycloheptanaphthalene 17 and the cycloheptaacenaphthene 57, along with the tricyclic ketone 14 and the carbocyclic benzenes indan (64), tetralin (65), and benzsuberan (66) were reacted with mixtures of fuming nitric acid and acetic anhydride, and the resulting nitro-acetoxy adducts were isolated. The evidence for the structure of the hydrocarbons, their precursors, and their nitro acetoxy adducts is discussed, and mechanisms are suggested for their formation.

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  • A study of some organic and organometallic stereochemical problems by crystallographic direct methods

    Brice, M. D. (1972)

    Doctoral thesis
    University of Canterbury Library

    The crystal and molecular structures of five compounds are described this thesis. Of the five, one is the organometallic cobalt carbonyl cluster compound, bis(methinyltricobaltenneacarbonyl), [CCo₃(CO)₉]₂. The other four are wholly organic and are classed as all 'light atom' structures. The compounds studied were chosen primarily because they were suitable subjects for the use of particular techniques of structure analysis which were new to this laboratory. Therefore, although each has considerable intrinsic interest, the five compounds are not in fact chemically related. The techniques referred to required the phasing of observed structure amplitudes using direct methods which involve statistical analyses of the X-ray reflection intensities. It was intended to develop practical procedures for applying these direct methods to crystallographic problems in this laboratory. This aim has been achieved as the symbolic addition procedure and the tangent formula have been used in solving all the structures reported here.

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  • Problems and methodology in the compilation of an atlas for American literature : Henry Thoreau : a case study

    Stowell, Robert Frederick (1971)

    Doctoral thesis
    University of Canterbury Library

    This thesis is an investigation of the "sense of place” in American literature and the use of setting in selected works by four major American authors. A theory about the importance of setting in American writing is postulated and four caegories are established for defining an author's use of setting in his work. Regional and local color writing are discussed because of their special interest in the physical environment of their characters. A survey is made of the importance of setting in the work of major authors from the time of Benjamin Franklin to that of Ernest Hemingway. The general problems involved in providing suitable maps and illustrations for an "Atlas for American Literature" are studied, and methods for solving these problems discussed. Examples of specific problems and solutions to these problems are provided by maps and illustrations for one book by each of three authors who represent important periods in American literary development, namely James Fenimore Cooper, Mark Twain and John Steinbeck. The latter half of the thesis is a comprehensive study of the setting of all of Henry David Thoreau's writings and the provision of maps and illustrations to accompany them. Maps by Thoreau, contemporary maps and modern reconstructions are included, as well as selected illustrations relevant to the settings of his work. A chronology of all of Thoreau's travels beyond the Concord and Boston area has been compiled and a partial index drawn up for the thirty-six maps.

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  • Development and use of computer techniques in x-ray crystallographic studies

    McLennan, Theresa J. (1978)

    Doctoral thesis
    University of Canterbury Library

    The crystal and molecular structures of four chemically unrelated compounds have been determined by X-ray crystallography. One compound is organometallic and it crystallises in a centrosymmetric space group while the others are organic and their space groups are non-centrosymmetric. The compound bis(triphenylarsine)hexafluorobuta-1,3-diene platinum crystallises in two forms. Traditional vector methods were used to solve the structure of the isomer reported here. This is a further example of an organometallic compound where an olefin, in this case hexafluorobutadiene, is co-ordinated to the metal atom by one olefin bond to form what may be described as a 'metallo-cyclopropane'ring. Direct methods were used to determine the structures of 1,1-dichloro-2,5-diphenylcyclopropabenzene and 4,5,6-tri-O-benzoyl-2,3-di-S-ethyl-2,3-dithio-D-allose diethyl dithioacetal. In the first of these compounds the cyclopropabenzene system is not quite planar and the phenyl substituents are twisted and bent from the plane of the benzene ring in the cyclopropabenzene system. The second of these analyses confirmed the molecular configuration of the tetra-thio aldose derivative as D-allo and established that the molecule has a bent-chain conformation similar to that found in solution. The conformation of a brominated compound, extracted as an acetate derivative of formula C₃₂H₅₅O₈Br from the seaweed species Laurencia thyrsifera, has been established. The compound's structure is related to squalene and was solved using Vector methods. In addition to these analyses unsuccessful attempts to solve the crystal structures of a dinitro-imidazole derivative (C₄H₄N₄O₄) and a compound thought possibly to be a tetracyclo-decane (C₁₅H₁₂N₄) are outlined. A significant part of this project involved the further development of the X-ray crystallographic program suite of the University of Canterbury which is used in all X-ray structure analyses. Particular projects contributing to this development are discussed.

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