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This work presents a new design for a gammavoltaic cell, based on diamond and the surface transfer doping it exhibits. The design evolved from the observation of gammavoltism in a diamond dosimeter during previous work at the University of Bristol. The work first gives an overview of gammavoltaics in literature, highlighting the small size of the field as it currently stands, and the difficulty in comparing between previous works due to the range of approaches used both for conceiving gammavoltaic devices, and for testing them. As part of this overview, it draws attention to some other radiovoltaic work to illustrate where gammavoltaics sit in a wider context. It then discusses the processes by which high-energy photons are converted to conduction electrons within a device. Discussion is split into high-energy photon scattering processes, electron scattering processes (for hot electrons), and charge transport processes (for lower-energy electrons and their holes). As the presented gammavoltaic design is based on diamond, space is then given to the historical context of diamond research and of research into diamond devices under irradiation. Three device-specific aspects of diamond research are then covered in greater depth: the formation of high- and low- barrier electrical contacts on diamond, and the surface transfer doping effect. With this background given, the design for a gammavoltaic cell on which this work is based, is presented: a thick, insulating diamond with opposing, dissimilar contacts, covered on all surfaces with a certain coverage of hydrogen termination. To marshal the lessons from existing gammavoltaic literature, and also to give clarity and structure to the experiments conducted for this work, five factors are introduced: comparability, accountability, capability, applicability and longevity. No gammavoltaic has yet seen a real-world deployment, to my knowledge. I assert here that each of these five factors has an important role to play in the conceptual development of the field and the progress it makes towards gammavoltaics becoming industrially useful. I define an energy range of 1 - 2000 keV, the Gamut, which I suggest contains all relevant photon energies for gammavoltaic purposes, both application and study. For similar reasons, I suggest a notation convention which lends itself to use for benchmarks in gammavoltaics, with two given directly: Co-60100픓, the volumetric maximum power-point density under a 100 Gy/h air KERMA dose rate of Co-60 radiation, in nW/cm³, and Co-60100픭, the analogous areal quantity, in nW/cm². A Theory chapter is included which gives a brief overview of the basic physics of traditional solar cells based on silicon pn-junctions, the equivalent circuit model which arises from this, and the use of the Lambert W function to derive an explicit I-V expression from the model. It then attempts to apply the same concepts to the diamond gammavoltaic cell presented in this work, although there are several elements which have not been included in the theoretical treatment at this time. An extended equivalent-circuit model based on opposing diodes, the opposing-diodes model, is derived from this circuit. Finally, the theory chapter discusses the fitting parameters space for both models, and the benefit of using orthogonal distance regression for radiovoltaic work, to account for the fact that uncertainty in the applied bias may be substantial as well as the measured current. There is also a Methods chapter which covers the computational aspects of the above as well as the other experimental methods employed in the work. The first set of results presented are for the purposes of capability and accountability. They seek to prove that the design presented here is capable of working, to a reasonable degree, as a gammavoltaic, and to verify that it works in the way intended. Due to the unusual method of hydrogen termination, required by the fact electrode contacts must be deposited prior to termination, an x-ray photoelectron spectroscopy study is presented which shows the enabling hydrogen termination to have consisted of approximately 0.3 monolayers. The second set of results here goes further down the route of accountability, using a chain of synchrotron experiments and GEANT4 simulations to first attempt to validate the modelling approach used in this work, and then attempt to probe the operation of a diamond gammavoltaic cell under high fluxes of photons as the energy is varied between 50 keV - 150 keV, the region in which Compton scattering being to dominate over photoelectric absorption for diamond. Unlike in work published on the latter experiment, conclusions drawn are fairly limited due to uncertainties about the method that have arisen since publication. The third set of results addresses the factors of comparability, applicability (to the gamma field in a nuclear waste store), and longevity (again, in the context of deploying in a nuclear waste store). Measurements are performed under irradiation from gamma rays from both Cs-137 and Co-60. In each case, air KERMA dose-rates of tens to thousands of Grays per hour are attained. An equivalent circuit model based on two opposing diodes is fitted to each curve in an attempt to extract quasi-physical parameters and observe their change with dose rate, to mixed success. For comparability, benchmark values are found of Co-60100픭 = 27 nW/cm² and Co-60100픓 = 179 nW/cm³. Longevity testing showed that the device design is promising for longevity. It suffered no catastrophic degradation after 800 kGy air KERMA of Cs-137, after an irradiation at 1,350 Gy/h air KERMA for over 3.5 wks. At most, degradation was around 16%, but this is an overestimate due to temperature and humidity effects also playing a role. The longevity status of the gammavoltaic design presented here is promising but requires more study, over longer periods of irradiation. The summary and conclusions of the work include avenues for improvement in the device, and early work that has been undertaken to address them. The thesis culminates with details of a demonstration in which a diamond gammavoltaic device powers a Bluetooth monitoring circuit, sufficiently to transmit a temperature and humidity measurement after charging from x-rays for 10 h. This is believed to be the first time a gammavoltaic has been used to power any kind of electronic device.

The overarching goal and ambition of this research is to realise a potential solution to the chemical instability found with known functionalised diamond surfaces. A sub-set of these form a dipole that gives rise to a negative electron affinity property that promotes enhanced electron emission at thermionic temperatures and has numerous technological applications including concentrated solar thermal power generation. The prime focus of the research presented in this thesis is the use of tin (Sn), a very nontoxic, abundantly available, less expensive heavy metal, as an alternative termination of the diamond surface. The suitability of tin was established using the density functional theory (DFT) where Sn and tin monoxide (SnO) groups used as a termination on the diamond (100) surface have resulted in a large adsorption energy of -4.4 eV in half monolayer configuration (HML) with an electron affinity of -1.43 eV and up to -6.5 eV in HML configuration with an electron affinity up to −1.37 eV, respectively. The NEA occurs as a result of dipole formation on the surface due to the shift in the electron density toward or in the vicinity of surface carbon atoms, realised through the electrostatic potential and density of states calculations. Lithium nitride solution was deposited on the diamond surface with subsequent annealing at higher temperatures to gain an insight into the mobility of the Li atoms on the diamond. Li atoms were seen to move from the surface into the near surface bulk and then back to the surface through the temperatures of 650°C - 750°C - 850°C, at which point the LiO was completely desorbed from the surface. This was seen to affect the bulk properties of diamond. An air stable sub monolayer of SnO nanoclusters was formed "reliably" on the surface of diamond (100) using physical vapor deposition. SnO was seen to impart an NEA of -0.02 eV to the diamond surface along with a reduction in the WF by 1.8 eV. Inclusion of Li atoms into this structure resulted in Li atoms taking up oxygen from SnO and forming SnOₓ-LiO₂ heterostructure with an NEA of - 0.42 eV and WF reduction by 2.3 eV. This interaction has also resulted in the increased stability of the Li on diamond surface. Only about 15% of Li was lost in the case of Li₂O-SnOₓ termination on diamond (100) compared to 47% lost in case of LiO terminated diamond at similar elevated temperatures.

Surface alloys can form spontaneously during the deposition of one metal onto another, especially in systems with a very large lattice mismatch that do not have bulk counterparts (so-called immiscible systems). Spontaneous surface alloying has been widely studied in Ultra High Vacuum (UHV) systems, but these new materials have not been exploited much in practical applications. Since a high control and scalability make a transfer to real and practical systems viable and versatile, surface alloying in an electrochemical environment is an ideal route to the design of new functional materials. This work presents an investigation of the surface alloying process during underpotential deposition (UPD) of Pb on Au(111) and Pb on Cu(100) in the absence and presence of strongly adsorbing anions, e.g. chloride or bromide. The phenomenon of surface alloying has been studied using several electrochemical protocols such as (1) polarisation at fixed potentials in the UPD region and (2) repeated potential cycling over a limited UPD range. By following the changes in electrochemical behaviour, the range of potentials and conditions at which the surface alloys form has been established together with quantification of their composition. Finally, the structural and compositional changes have been investigated by surface sensitive techniques such as X-ray Photoelectron Spectroscopy (XPS), Ultraviolet Photoelectron Spectroscopy (UPS), Energy-Filtered Photoemission Electron Microscopy (EF-PEEM) and Work Function (WF) mapping.

Electrodeposition of Au and AuxAg100-x alloys is commonly based on cyanide baths. In this work, AuxAg100-x alloys have been electrodeposited using less toxic thiosulphate solutions. Alloys of different compositions were obtained from solutions with different Au+:Ag+ ion ratios by constant potential deposition. XPS analysis of films of different thicknesses showed that composition of films was homogenous and consistent during growth. Electrodeposited alloys were used to obtain nanoporous gold (NPG) by selective electrochemical Ag dissolution. The potential at which Ag dissolution takes place changed to more positive potentials with increase of Au content as expected. The porous structures were characterised electrochemically by surface area measurements using Pb underpotential deposition (UPD). It was observed that repeated cycling of Pb UPD on NPG led to changes in surface porosity. Following up on studies of surface-alloying during Pb UPD on Au in our group, Pb UPD was explored as a 'tool' to alter the porosity size. The study has shown changes in porosity size depending on number of potential scans, scan rate and initial size of Au ligaments. Electrodeposited AuxAg100-x alloys were analysed by Pb and Cu UPD processes. The main peaks of Pb UPD characteristic for pure Ag shifted towards more positive values for alloys with higher Au content. Also, Pb UPD voltammograms on AuxAg100-x showed an unusual peak, related to the Ag compound and thiosulphate after a systematic study of Pb UPD on pure Ag films electrodeposited from three different solutions. Cu is a metal that forms UPD layer on Au but not on Ag. Cu UPD voltammograms showed similar shifts in the peaks potentials towards more positive values with increase of Au content in alloys. Charges measured for Cu UPD layer decreased with increase in alloy's Ag content. The observations and measurements followed a trend observed on bulk alloys previously reported.

Research is presented for expanding the capabilities of a pulsed-DC PA-CVD reactor and increased understanding of diamond growth parameters within. Expanding operational capabilities involved upgrades to the electrode and cooling set up through several iterations. The original design was replaced with smaller electrodes and improved cooling, allowing for higher power inputs and more reliable and stable plasma production. This resulted in long, stable growths producing high-quality diamond films. Each upgrade to the electrode design required operational Taguchi optimization in order to understand the new limitations as well as increase understanding of parameter influence on the grown diamond. The final design incorporated novel asymmetric electrode cooling and a gas/water cooled cathode. The improved plasma stability allowed for spectral plasma analysis, providing insight to Hβ and C₂* radical distribution and primary plasma reaction pathways. Spectral and growth analysis of closed chamber, zero gas flow growth was also explored, a first with this type of instrument. Diamond quality does not appear to be affected by the closed chamber growth, but plasma stability severely limited extended testing. With a new, cooler anode/substrate complex, low melting point substrate growth was trialled. Silicon growth produced limited success, reflecting the recent literature's limited discussion of the material, but a novel copper substrate produced rapid growth of free-standing high-quality diamond films. The production of these films produced interest in the exploration of diamond/epoxy nanocomposites. DND and HPHT diamond powder nanocomposites were manufactured and mechanically tested for a variety of physical properties. The HPHT nanocomposites showed similar moduli to the DND equivalent with less reduction in failure strain or UTS. Overall, this showcased promising variations between materials that could be used for future applications.

The aim of this thesis is towards a solar thermal type of energy converter, using a plasmonically-enhanced diamond based thermionic converter. The approach was to first form a strong fundamental basis of understanding on the diamond electronic properties, including its electron emission behavior and the use of ultra-high vacuum techniques to analyze them. Modification of the diamond surface was then studied to find an optimum structure for thermionic emission, along with possible emission enhancement mechanisms. Finally, plasmonic structures were added by different methods where their feasibility was investigated. Angle-resolved photoemission spectroscopy was employed to analyze the diamond electronic band structure. This allowed the valence band width of diamond to be determined at approximately $18.3$ eV, which has significant implications for photoelectron spectroscopy with lab-based light sources. And from the electron emission perspective, low energy electron emission was found to originate from unoccupied electronic states which gave well defined and ordered emission structure, meaning that unoccupied states can be directly mapped using secondary electrons. The emission behavior was also determined to have no preferential perpendicular momentum selection. As thermionic emission occurs in this region, its behavior can be predicted and studied in detail using the proposed model. These methods then supported the study of surface functionalization and graphene application on diamond, where the general electronic effects and interactions on diamond from surface modifications, such as band bending and work function are inferred. Thermionic emission from diamond was found to be readily enhanced through various mechanisms, which strongly points to further enhancements via surface plasmonic resonances. Plasmonic structure generation on diamond surfaces was then studied using application of atomic gold layers. Surface characterizations of the gold-diamond structure along with optical responses were considered to determine the most suitable approaches. With this approach, a highly efficient diamond-based electron emitter can be realized for thermionic energy conversion applications.

Thermionic energy conversion holds great promise for effective and clean energy production. Diamond has a unique set of properties that distinguish it as an excellent potential thermionic emitter, a crucial component of thermionic energy converters. In particular, the hydrogen-terminated diamond surface exhibits a negative electron affinity, which allows for efficient emission of electrons. The hydrogen termination is not stable at elevated temperatures, which necessitates investigating alternative candidates such as titanium. This work is primarily concerned with the investigation of the electronic properties and surface stability of titanium containing diamond surface terminations to assess their potential as a thermionic emitter. Ab initio computational modelling of various titanium surface terminations showed that titanium nitride, titanium oxide, and titanium carbide all have the potential to exhibit negative electron affinities. The titanium nitride surface termination showed similar stability as the hydrogen termination, while the titanium oxide surfaces exhibited better stability. The titanium carbide terminations proved the most stable, with promising electronic properties. Titanium-oxide- and titanium-nitride-terminated diamond surfaces were prepared using techniques such as acid and plasma treatment, chemical vapour deposition, and e-beam evaporation. The fabricated surfaces were annealed at temperatures of up to 1000 °C and analysed primarily using X-ray and ultraviolet photoelectron spectroscopy. For most of the titanium surfaces, the oxygen or nitrogen desorbed by 1000 °C while the titanium did not, resulting in titanium-carbide-terminated diamond. Though these titanium carbide surfaces typically exhibited moderately higher work functions than the equivalent titanium oxide or nitride terminations, they still exhibited negative electron affinities. Therefore, titanium-carbide-terminated diamond surfaces were found to be stable at elevated temperatures while also exhibiting favourable electronic properties.

This thesis presents a joint computational and experimental approach to developing a novel diamond surface termination with aluminium that has a negative electron affinity (NEA). There is a need for a thermally stable NEA for thermionic applications, since hydrogen termination desorbs from the diamond surface at thermionic temperatures. The choice of aluminium is based on it being a light, electropositive element that bonds strongly to different diamond surfaces. Using density functional theory, the adsorption of Al onto bare, oxygenated and nitrogenated diamond surfaces was studied. The two key parameters considered were the adsorption energy and the electron affinity values, for different coverages and configurations of Al. NEA values of up to -1.47 eV and 1.88 eV were observed for Al addition to the (100) and (111) bare surfaces, respectively, at 1 monolayer (ML) coverage, and up to -1.36 eV and -2.17 eV for Al addition to the (100) and (111) oxygen-terminated surfaces, respectively, at 0.25 ML coverage. Al adsorbed more strongly on the ketone O-terminated surface than the ether surface. Adsorption energies for the AlO-terminations were up to -6.36 eV/atom and -8.19 eV/atom for the (100) and (111) surfaces, respectively, at 0.25 ML Al coverage, considerably larger than that of H termination (~-4 eV/atom). Three different oxidation procedures were investigated experimentally. It was determined that oxidation of diamond by UV/ozone treatment results in a large ketone component on the surface, whilst also having ~1 ML coverage. The surface structure and electronic behaviour were determined for both hydrogen and oxygen terminations. AlO-terminations were fabricated experimentally by depositing Al onto O terminated diamond. Three different methods were explored: (i) thick-film deposition of Al followed by an acid etch to remove excess metal, (ii) thin-film deposition of Al by atomic layer deposition, and (iii) thin-film deposition of Al by electron-beam evaporation. Low work function and NEA were observed for each method, but these values were spatially and temperature dependant. Annealing caused a change in surface structure, identified as the incorporation of O atoms into the Al layer. Tests of thermionic emission showed a small emission current density, but at a higher temperature than attainable for H termination. Thus, AlO-terminated diamond shows promise but further optimisation is required for use in devices.

This thesis reveals and explores contemporary relationships between film education, film industry and film culture within a UK context through a series of interviews, data analysis, historical research and international case studies. It highlights what appear to be binary oppositions within film such as divisions between theory and practice, industry and academia or art and entertainment and interrogates how they have permeated film education to the point where the relationship between film studies and film practice is polemical. Also, the thesis investigates how a relationship between two binary areas might be re-­engaged and it is within this context that this thesis addresses contemporary issues within UK higher education and national provision of film education. There is detailed analysis of UK film policy alongside the philosophies and practicalities of filmmaking to establish how connected the practice of filmmaking is to the film industry and national strategy. An international perspective is provided through the analysis of the film school systems in Denmark and the U.S. and this postulates potential future directions for UK film education, particularly within the university sector. A main focus of the thesis is to question film education by engaging with the voices of actual filmmakers and also via data analysis of the educational background of filmmakers as a way of developing film education. The thesis is undertaken at a time of major changes across film and higher education. Film production, distribution and consumption have undergone major technological evolution and the structures that were once in place to facilitate graduate movement into the workplace are changing and shifting. Simultaneously the identity of the university as a place of skills training or critical development is under consistent scrutiny. With this in mind this thesis seeks to engage with the potential future for film education.

A project was undertaken to develop a system to predict the probability of a flood occurring on a particular river catchment as a result of convective storm rainfall, The system is designed for use in developing countries and uses data from the Advanced Very High Resolution Radiometers (AVHRR) aboard the NOAA polar orbiters and the synthetic aperture radar (SAR) of the ESA ERS satellites. The system uses data from the SAR to determine soil moisture content (SMC). From observed differences in SMC it is possible to estimate the evapotranspiration at the surface. In combination with AVHRR derived net radiation, the evapotranspiration,in turn, is used to calculate the sensible heat flux. The sensible heat flux is used in a simple convective model to estimate the height of the atmospheric boundary layer and the velocity of an ascending parcel of air. From this the probability of convective storm occurrence and maximum rainfall is calculated. By inputting the rainfall into a simple, lumped hydrological model the flood potential is found. The system has been tested on two catchments: The River Irwell in Northwest England and the Kafue River in Zambia with good results. Investigations have been made into the advantages of combining the satellite-derived fields with those produced by numerical weather prediction models and some aspects of the system are observed to benefit from this approach.

This thesis studies the modification of the surface work function from the perspective of its potential application to the field of energy generation. In this case, improving thermionic electron emission from diamond surfaces is the focus of this thesis, as a diamond based device can be used for power generation when implemented as a thermionic energy converter. The success of diamond-based thermionic energy converters strongly relies on the quality and stability of the diamond surface, which has to provide a low work function and a negative electron affinity. These characteristics, low work function and negative electron affinity, are achieved by terminating the diamond surface with a monolayer of hydrogen. However, the poor stability of this surface at high temperatures, at which a thermionic energy converter would operate, is the main drawback for the successful development of diamondbased devices. Thermionic emission from diamond surfaces was studied, culminating with the proposal of a new theoretical model for thermionic emission from hydrogenated diamond surfaces. This new model, to the best of the author's knowledge, is the first to successfully reproduce the behaviour of the thermionic emission current from hydrogenated diamond surfaces, including the decrease of emission current due to the desorption of hydrogen. As a consequence, the new model allows the extraction of additional information about the surface properties of diamond, like the hydrogen activation energy of desorption Ed or the Richardson constant A. Additionally, it is now possible to relate the components of the emission current with certain surface phases or chemical states of hydrogen on the diamond surface. This finding led to the conclusion that, for <100> single crystal diamond, most of the emission at high temperatures comes from flat terraces with a C(100)-(2×1):H reconstruction. Therefore, in order to improve thermionic emission from diamond, surface treatments should be applied to the surface to promote the formation of this surface phase. In addition, single crystal diamond proved to be a much better emitter than polycrystalline diamond by emitting 1.5 mA/cm2 as compared to 0.3 mA/cm2 emitted by the polycrystalline diamond. An alternative method for the modification of the surface work function was investigated in order to assess its potential application to diamond surfaces. This method consists on the use of light excited plasmo-electric potentials. This phenomenon is quite novel, so the research on this thesis is more focused on increasing our understanding of the physics of this effect that on its immediate application to diamond surfaces. Hence, plasmo-electric potentials on silver nanoplates deposited on indium-tin-oxide were analysed. By studying the transient behaviour of plasmo-electric potentials, it was found that they are surprisingly long (τ ≈ 100 s), which is unusual for a plasmonic-based effect, that normally operates on the picosecond regime. It was concluded that this was caused by the charge transport characteristics of the nanoplate-substrate interface. This is because plasmo-electric potentials are caused by the transfer of electrons in or out the nanoplate, which modifies its electrochemical potential and in turn its work function. Moreover, it was found that plasmo-electric potentials are present on the same nanoplate with opposite signs, which is believed to be caused by impurities deposited on the surface of the nanoplate. Lastly, in order to apply plasmo-electric potentials to improve thermionic emission more research is needed to better understand the physics of this phenomenon. However, it was found that plasmo-electric potentials could have a strong relation with plasmon-assisted catalysis, which could open a new and exciting pathway for novel research.