VictorJuiz/thesis huggingface dataset:
Photoelectron spectroscopy of metal oxides

The work described in the thesis divides essentially into two parts: (1) the experimental measurements of photoelectron spectra of a variety of solid metal oxides; and (2) the theoretical investigation of electronic structure problems concerning the final states of the photoionisation process (the states of the ionised system), much of which is directly relevant to the experimental studies.
The spectroscopic investigation concentrates upon transition-metal oxides (for example, the rutile series MO2 various sesquioxides M2O3, and ternary systems such as ilmenites (MTiO3). Such materials are of considerable general interest by virtue of their diverse electronic properties, and their technological importance. Photoelectron spectra were measured from polycrystalline samples, using both UV (He I and He II) and X-ray (Mg Kα) excitation. The sequential measurement of UV- and X-ray photoelectron spectra is an important element of this work. From the technical point of view another important feature of the experimental work is the attention given to preparation of clean sample surfaces.
The theoretical work concerns the 'fine structure' of photoelectron signals due to (1) electrostatic coupling effects and (2) electronic relaxation in the final state. The ionic approximation is invoked, all electronic structure calculations being performed on atomic species.
Both core electrons in general, and the outer-shell electrons of heavy atoms, are highly relativistic in nature, their description demanding the use of Dirac-Fock theory rather than the simple Hartree-Fock model. A major feature of the theoretical work described is the use, where appropriate, of Dirac-Fock theory to obtain required atomic wavefunctions and state energies. The use of a relativistic model proves essential in many cases.
Physical properties of metalloporphyrins

In this work, a number of physical techniques are used to study the behaviour and properties of different metalloporphyrin systems under varying conditions. The behaviour of these systems is interpreted so far as is possible in terms of relations between structure, both geometrical and electronic, and function.
In Chapter 1, a general survey of porphyrin structure, activity, properties and relevance is provided as an introduction. The significance of porphyrins in the biological context is briefly discussed, and arguments are presented to justify the scope of model systems in providing an understanding of larger biological systems.
Chapter 2 is concerned with the basic theory and practice of the physical techniques employed.
In Chapter 3, the electronic properties of iron porphyrin derivatives in which spin crossover phenomena are present are studied. With certain derivatives, unusual and anomalous features manifest themselves in the magnetic moment and PMR, Mössbauer and electronic absorption spectroscopic data. These results are discussed and interpreted in terms of a number of theories of increasing sophistication.
In Chapter 4, PMR studies of some 'natural' ferric porphyrin complexes are described. Paramagnetic spectral shift data are obtained, analysed and interpreted in terms of a valid spin delocalisation theory. The effect of substituents on the porphyrin ring and on the axial ligand upon the bonding interactions is observed.
In Chapter 5, some mixed ligand ferric octaethylporphin derivatives are studied by means of PMR spectroscopy. Hyperfine interaction data are obtained and partially rationalised in terms of spin density distribution at particular axial ligand positions.
In Chapter 6, some monomer and oxo-bridged dimer porphodimethene ferric complexes are studied by means of PMR spectroscopy in order to examine the effect of partial saturation at the porphyrin periphery on bonding interactions, and on electron spin transfer from the iron atom.
Cardiac monitoring in ambulant subjects

Miniature magnetic tape recorders permit physiological data to be collected from ambulant subjects. During 24 hours the signals from some 100,000 heart beats can be registered but the analysis of this amount of information poses technological problems.
Monitoring of an oscilloscope display of the signal replayed from tape was an early method. A record-replay speed ratio of 25:1 enabled a tape to be scrutinised in one hour but was a tedious task. Digital computers were being used to analyse standard ECGs of short duration but were expensive and complex.
It appeared that a comparatively simple semi-automatic analyser based on analogue techniques would be practical, given the limited objective of identifying ventricular and supraventricular extrasystoles, ventricular and supraventricular tachycardias, bradycardia, gaps or short periods of asystole and change in QRS wave-form.
Commercial systems using variations in width or area of the QRS complex as criteria for classifying ventricular extrasystoles proved to be unsuccessful in real time analysis and seemed unlikely to be suitable for adapting to high speed operation.
It appeared possible that the QRS wave-forms from ventricular extrasystoles might contain a higher proportion of low frequency components than those from contractions arising in the atrium and that they might be segregated by a method based on this hypothesis.
No information could be found on this subject in the literature, so measurements were made which showed that ventricular extrasystoles contain a high proportion of frequencies around 2.8 to 3.8 Hz, whilst for sinus beats the predominant frequencies are near 13 Hz.
This being so, an analyser using analogue filters was developed to exploit the discovery.
In validation tests on 51 recordings the incidence of false positive or false negative detection of premature beats ranged from 0% to 5.8%, whilst misclassification of ventricular and supraventricular premature beats occurred with a frequency of 0% to 1.5%. No errors occurred in the classification of tachycardias, bradycardia or gaps.
Subsequently the analyser has been used in a survey of the 24-hour ECG of 100 normal subjects, in a study of the diurnal variation in the incidence of ventricular extrasystoles and in several drug trials.
Studies in relaxation

This work concerns itself with the exact study of the dynamical properties of two model systems. After a brief summary of theory and concepts previous work is discussed, and this provides the motivation for the formulation of the first model. This quantum mechanical lattice model and some of its equilibrium properties are described in Chapter II. The dynamical problem to be studied is formulated in Chapter III; this is essentially the study of the time evolution (generated by the Hamiltonian) of a finite system at temperature T1 coupled to an infinite copy of itself at a temperature T2 and acting as a heat bath for the system. The problem is solved for the special case, when the coupling as scaled by the parameter γ, takes the value γ = 1.
The general case for arbitrary γ values is treated in Chapter IV. It is shown that the system approaches the equilibrium state of the heat bath in a non-exponential manner, provided the spectrum of the Hamiltonian is continuous and does not have a discrete part. This result is in complete accord with the findings of other work summarised in Chapter I. The mixing properties of the model and behaviour of the relaxation rate in the weak coupling limit are studied in Chapter V. The model is shown to fail to behave as a calorimeter and in view of this result the relevance of the concept of mixing to irreversible behaviour is discussed. The main conclusions and results for the model are summarised at the end of Chapter V.
The second model discussed, was first introduced by R.J. Glauber to study the dynamics of the Ising chain. The main feature here is that the time evolution is defined through a Master equation, and the associated stochastic operator. It is shown in Chapter VI that exploiting fully the free fermion character of the stochastic operator for the Glauber model, it is possible to provide a simple method to the study of the dynamics of the Ising Chain.
A study of the reactions of flavanoids with nucleophiles

The reactions with nucleophiles of 4-substituted flavans variously methoxylated are studied. The partial epimerisation of 4β-acetoxyflavans in acetic acid/acetic anhydride mixtures and of flavan-4β-ols in aqueous acid, providing preparatively useful routes to 4α-acetoxyflavans and flavan-4α-ols, occur by an SN1 mechanism. Reaction is greatly facilitated by methoxyl groups at the 5- and, especially, the 7-position. No effect of B-ring substitution on reaction rates was detected. Equilibrium mixtures of epimers studied contained 5–10% of the 4α-isomer.
2,3-Trans-3,4-trans-diacetoxy-5,7,3′,4′-tetramethoxyflavan (1) is considerably less reactive than 4β-acetoxy-5,7,3′,4′-tetramethoxyflavan (2). An equilibrium mixture of (1) with its 4-epimer contains ca. 16% of (1). Some puzzling reactions reported in the literature are explained by the results of this study or shown to be wrong.
The 4-carbocation generated by decomposition of (2) also reacts with phenols, providing the first satisfactory route to 4α-aryloxy-5,7,3′,4′-tetramethoxyflavans. The phenols (and yields of aryloxyflavan) are: phenol (60%), m-methoxyphenol (46%), m-benzoyloxyphenol (51%) and 3,5-dimethoxyphenol (9%). Generation of the necessary carbocation for synthetic purposes from flavanoids possessing a 3-oxygen substituent or lacking a 5-methoxyl substituent requires a better leaving group. Benzoate and p-nitrophenoxy are convenient for ease of preparation and reaction. Thus, 4α-phenoxy-7,3′,4′-trimethoxyflavan (39%) and 2,3-trans-3,4-cis-4-phenoxy-5,7,3′,4′-tetramethoxyflavan-3-ol (15%) and its 4-epimer (1%) are prepared.
7-Hydroxyflavanoids, intended to act as nucleophiles in syntheses of ether-linked flavanoid dimers (modelling postulated naturally occurring polymers) are synthesised with the aid of protection of the 7-hydroxyl group. Those which possess a 4-acyloxy group or 3,4-double bond are too labile, particularly in the presence of base, to be isolated. 7-Hydroxy-3′,4′-dimethoxyflavanone (3), 2,3-trans-3-benzoyloxy-3′,4′-dimethoxyflavan-7-ol (4) and also 2,3-trans-3′,4′-dimethoxyflavan-3,7-diol and 2,3-trans-3,4-cis-3′,4′-dimethoxyflavan-3,4,7-triol were isolated. The reagent osmium tetroxide/N-methylmorpholine-N-oxide was used to accomplish stereoselective bis-hydroxylation of flav-3-enes in high yield.
(3) And (4) react with 4β-(p-nitrophenoxy)-5,7,3′,4′-tetramethoxyflavan. 7-(5,7,3′,4′-tetramethoxyflavan-4α-yloxy)-3′,4′-dimethoxyflavan-4β-ol (formed by sodium borohydride reduction) and its acetate, and 7-(5,7,3′,4′-tetramethoxyflavan-4α-yloxy)-2,3-trans-3-benzoyloxy-3′,4′-dimethoxyflavan were isolated. Their structures are confirmed by n.m.r. and mass spectroscopy.
Organometallic chemistry of molybdenum and cobalt and related studies

The thesis concerns developments in the chemistry of mono- cyclopentadienylmolybdenum derivatives and (η-allylic)monocyclopentadienylcobalt derivatives.
Improved synthetic routes to the compound (Mo{η-C5H5}2dppe)(PF6)2 are described.
It is shown that there are structural isomers of the compound Mo{η-C5H5}{η-C5H6}dppe)PF6 which differ in the orientation of the η-C5H6 ligand on the metal.
The new compounds (Mo{η-C5H5}2dppm)(PF6)2, (Mo{η-C5H5}2{dppm}H)PF6, (Mo{η-C5H5}2{dppm}Cl)PF6, and (Mo{η-C5H5}2{NC-CH3}2) have been prepared.
The new compound Mo{η-C5H5}{dppe}H3 has been synthesised by treatment of Mo{η-C5H5}{dppe}Cl3 with NaAlH2(OCH2CH2OCH3)2. The reaction of the trihydride with butadiene led to isomers of the compound Mo{η-C5H5}{1-CH3-η3-C3H4}dppe. These undergo hydride abstraction giving isomers of the compound (Mo{η-C5H5}{η4-C4H6}dppe)PF6.
New synthetic routes to the compound Mo{η-C5H5}{dppe}H3 were investigated. Treatment of Mo{η-C5H5}{dppe}Cl3 with NaBH4 and separately with HSn{n-butyl}3 gave the new compounds Mo{η-C5H5}{dppe}BH4 and Mo{η-C5H5}{dppe}{Sn(n-butyl)3}H2 respectively.
The new compounds Mo{η-C5H5}{η3-C5H7}dppm and Mo{η-C5H5}{dppm}Cl3 have also been prepared and characterised.
The chemistry of the (η-allylic)monocyclopentadienylcobalt system was studied with a view to understanding the factors leading to regiospecific addition on the polyene ligands of organometallic cations.
The new compounds (Co{η-C5H5}{η-C3H5}PR3)(PF6), (PR3 = PPhMe2, PMe3), (Co{η-C5H5}{1-CH3-η-C3H4}L)(PF6) (L = CO, PMe3), (Co{η-C5H5}{2-CH3-η-C3H4}L) (PF6) , (L = CO, PMe3, Py, NH3) , Co{η-C5H5}{2-CH3-η-C3H4}I and Co{η-C5H5}(1-CH3-η-C3H4}Br were prepared and characterised.
The reactions of many of these compounds towards addition of hydride or methyl anion were studied. New reactions observed included the reaction of (Co{η-C5H5}{η-C3H5}PMe3)PF6 with MeLi to give the unexpected product Co{η-C5H5}{PMe3}Me2.
Reaction of Co{η-C5H5}(CO}I2 with PMe3 gave (Co{η-C5H5}{PMe3}3)I2. Treatment of (Co{η-C5H5}{PMe3}3)(PF6)2 with MeLi gave Co{η-C5H5}{PMe3}Me2.
The compound (Co{η-C5H5}{PPhMe2}2H)PF6 was isolated in the reaction of Co{η-C5H5}{PPhMe2}I2 with isopropyl magnesium bromide.
The Introductory Chapter of the thesis reviews known chemistry pertinent to the studies described above.
Asymmetries in nucleon transfer reactions induced by polarized protons

Nucleon transfer reactions play an important part in studies of nuclear spectroscopy, and it is necessary that the basic reaction theory should be thoroughly examined. In the case of two nucleon transfer reactions, this examination has been confined to the differential cross section since a proper study of polarization phenomena in these reactions has not been made. In this thesis, the results of a number of asymmetry measurements in double pick-up reactions will be reported. These measurements, based on (p,t) and (p,3He) experiments, were performed at the Rutherford High Energy Laboratory using the 50 MeV polarised proton beam from the linear accelerator. During the course of this report, the techniques of experimentation with such a beam will be described. The differential cross sections of the reactions were measured with the more intense unpolarised beam, and these results will also be presented.
An analysis of the data in terms of the distorted wave Born Approximation theory will be given in Chapter 5. The theory, in its two most frequently used forms, is outlined in Chapter 1. Special attention is paid to the consequences of neglecting spin-orbit coupling in the description of the optical model potentials. A summary is given in Chapter 2 of a general, spin-dependent distorted wave computer programme which was written as part of this research so that the DWBA analysis could be made. The programme is based on a code initially written specifically for deuteron stripping.
In the analysis, it will be shown that the usual zero-range spin-independent form of the nucleon transfer process is unable to account for the experimental observations. The two forms of double pick-up theory will be compared, and the possibility of avoiding the zero-range approximation will be investigated. In fact, it will be seen that finite-range corrections are essential to a proper analysis of the data. The importance of interference effects and spin-orbit coupling in two nucleon transfer reactions will b« evaluated. The results of two optical model analyses of published cross section data are included in a discussion of the triton and 3He optical potentials. Finally, a possible new method of examining the relative phases of nuclear wave function components will be described.
Some chemical applications of magnetic resonance

This thesis describes the construction of a very versatile broadline 10-100MHz frequency swept nuclear magnetic resonance spectrometer equipped with a 50 kilogauss superconducting magnet.
Measurements have been made, using this spectrometer, to obtain chemical shifts of the 133Cs ion to high precision and to very low concentrations (.005M) in aqueous and non-aqueous media. Remarkable effects have been observed and a theory is proposed that can predict the ion-ion contribution to the chemical shift in solution.
Chapter 1 describes the n.m.r. experiment and discusses factors affecting the signal to noise ratio that are relevant for the construction of the spectrometer.
Chapter 2 gives a brief description of the properties of the superconducting materials used to wind the magnet for the spectrometer and describes the construction and handling of the magnet and its related components.
Chapter 3 describes experiments made on the superconducting magnet to determine and improve its homogeneity.
Chapter 4 gives an account of the construction of the spectrometer and cites examples of its performance.
Chapter 5 outlines a theory proposed by Dr. R.R. Sharp of this research group to interpret the cesium chemical shifts observed.
Chapters 6 and 7 describe the measurements of cesium chemical shifts in aqueous and non-aqueous media. These shifts are interpreted in terms of the theory proposed in chapter 5.
The Appendix contains the raw experimental data obtained for this thesis.
Some problems in algebraic geometry

Let X be a protective non-singular algebraic variety over an algebraically closed field k. Let f: X &longrightarrow; X be an endomorphism of X and let F be a locally free sheaf on X. Then the vector spaces Hq [X;F] are known to be of finite rank and to be zero except for finitely many integers q. Let Φ: f*F &rightarrow; F be a morphism of sheaves. Then endomorphisms, eq, of each Hq [X;F] may be constructed as the composite: Hq[X;F] f*&longrightarrow; Hq[X;f*F] Φ*&longrightarrow; Hq[X;F]. Set L(f,F,Φ) = ∑ (-)qtrace(eq) .
If f has a non-singular fixed point set and subject to a slight restriction on the nature of the endomorphism induced by f on the normal bundle of each fixed component, Y, formulae are obtained of the form:
L(f,F,Φ) = ∑Y v'(Y,Φ),
with the sum being taken over the set of fixed components, in the two special cases:
(α) f is periodic with period prime to the characteristic of k.
(β) each fixed component is a point or a curve.
The definition of v'(Y;Φ) involves Chern characters and the like of the restriction of F and Φ to Y, as well as the induced action on the normal bundle.
If k has characteristic p ≠ 0, in case (α) a stronger p-adic lifting of the above formula is obtained.
The methods used are setting up an appropriate formalism and using the theory of derived categories in homological algebra. The algebraic geometry used is essentially that of the Borel-Serre paper (1958) vintage.
Structural investigation of some molecular complexes, and their related compounds

The reduction of benzotrifuroxan(I) by triethyl phosphite gives a crystalline 1:1 molecular complex of benzotrifurazan(II) with triethyl phosphate ester.
The structure of the complex (at -120°C.) was solved by X-ray crystallography and the molecules were found to be associated by a weak 'polar' interaction between the phosphoryl (P=0) bond of the phosphate and the molecular system of benzotrifurazan. The phosphoryl bond was almost coincident with the three-fold axis of the heterocycle.
The reaction of triphenyl phosphine with benzotrifuroxan was very complex and the product contained a large number of coloured compounds but no benzotrifurazan. Five crystalline compounds were isolated in small yield: a red, a light green, a yellow, a darker green and traces of a blue compound. Analysis of the first four showed that they contained both nitrogen and phosphorus but the physical data for the compounds gave little further information.
The structures of all five compounds have been solved by X-ray crystallography.
The red compound is a molecular complex of an aci- nitro- benzo- difurazan, associated as an ion pair with protonated triphenyl phosphine oxide(III). There is also a close approach of the planes
through two difurazan molecules and the red colour is thought to result from charge transfer between these two molecules.
The light green compound is a triphenylphosphine-nitroso-benzo- difurazan and is best represented as (IV). The colour is attributed to the aromatic nitroso chromophore.
The yellow compound is a sym-triphosphazine-trinitrobenzene and is represented as (V). The central C6 ring is distorted from a regular hexagon by the nitro groups bonded to it, and the planes of these nitro groups are almost perpendicular to the planes of the central ring.
The blue compound is an unusual diphosphorane (VI). The central C6 rings are deformed into boat conformations without completely destroying the associated π system and the geometry of the compound is that expected for an overcrowded aromatic molecule.
The structure of the dark green compound (VII) was determined by Miss J. M. Evans (Oxford University).
The reaction mechanisms for the reduction of benzotrifuroxan by triphenyl phosphine and by trialkyl phosphites is discussed within the context of the general reactions of P(III) compounds, and possible methods are suggested for the formation of the red, light green and yellow compounds and for the phosphate ester complex.
The study of nuclear reactions at intermediate energy

Angular distributions were determined for inelastic proton scattering to ten residual states in Si28. Measurements were carried out at 100 KeV steps in the incident energy range of 12 to 15 MeV. Since the purpose of the experiment was to search for intermediate structure in the inelastic reaction excitation functions, all determinations were made with a beam energy resolution of 100 KeV, The Van de Graaff accelerators of the University of Oxford were used for the experiment. The analysis of the 1000 proton spectra recorded in the course of the experiment was performed entirely by computers.
It was found that the angular distributions change rapidly with incident proton energy, and that the reaction excitation functions exhibit structure of the intermediate type. Cross-correlation analysis revealed that there is significant correlation between the structures associated with the different reaction excitation functions.
The experimental data were compared with the predictions of the doorway state theory of intermediate structure. It was found that both the characteristics of the intermediate structure in the excitation functions and the existence of correlation between the structures of the different excitation functions are in accord with the predictions of this theory.
The experimental results were also considered in relation to the statistical theory of nuclear reactions. It was found that the experimental values of the mean squared deviation of the cross-sections associated with particular inelastic reactions were in reasonable agreement with the values calculated on the basis of this theory. In the experimental situation studied it was found that this theory also offers some explanation for the existence of correlation between the structures associated with the different excitation functions.
It was concluded that both the doorway state theory and statistical theory provide possible interpretations of the observed intermediate structure.