Dissertations / Theses: 'Electron gas'

1

Prance, Jonathan Robert. "Cooling an electron gas using quantum dot based electronic refrigeration." Thesis, University of Cambridge, 2009. https://www.repository.cam.ac.uk/handle/1810/244593.

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Studies of two-dimensional electron gases (2DEGs) in semiconductors form an active and productive field of condensed matter physics research. As well as having interesting inherent properties, they are used as the foundation for constructing various nano-scale electronic devices, such as quantum wires and quantum dots. Conventionally, low temperature measurements of 2DEGs are made by cooling the sample to 1.5 K with liquid Helium-4, to 300 mK with liquid Helium-3, or even down to a few mK using a dilution refrigerator. However, at lower temperatures the electron gas becomes increasingly decoupled from the lattice in which it resides. Below ~ 1 K the coupling can be weak enough for the electron gas to be significantly elevated in temperature due to parasitic heating. In this thesis we present the experimental and theoretical investigation of a refrigeration scheme that has the potential to cool 2DEGs below the temperatures currently available. Cooling to ever lower temperatures would be beneficial for studying fragile fractional quantum Hall states, non-Fermi-liquid behaviour in bilayer 2DEGs, or interactions like the Kondo effect that occur between quantum dots and 2DEGs. The scheme we investigate is called the Quantum Dot Refrigerator (or QDR) and is based upon the energy selective transport of electrons through the singleparticle states of quantum dots. By using a pair of dots, both hot electrons and hot holes can be selectively removed from an otherwise electrically isolated 2DEG. The result is a net current that continuously removes heat. This type of refrigerator is best suited to be used in conjunction with a dilution fridge or Helium-3 system to provide a final stage of cooling. The scheme was first investigated theoretically in 1993 by Edwards et al. but, to our knowledge, has never before been demonstrated experimentally. We detail the fabrication and measurement of a QDR device that is designed to cool an isolated 6 µm2 2DEG. In order to interpret the behaviour of the device, a model was developed to take account of electrostatic interactions between the components of the system (the quantum dots and the isolated 2DEG). Electrostatic interactions were found to be significant for our design, but were neglected in previous work. Our model predicts that their presence complicates, but does not invalidate, the principle of operation of a QDR. By comparing measurements of the current through the QDR with predictions of the model, we show that the observed behaviour is consistent with cooling of the isolated 2DEG by up to 100 mK at ambient temperatures around 250 mK. Although these temperatures are well within the reach of conventional refrigeration techniques, the results are a compelling proof-of-concept demonstration that the QDR principle is sound and can achieve significant refrigeration in the right conditions. Finally, we discuss future directions for improving QDR performance and characterisation, and for lowering the achievable base temperature. We also suggest how QDRs could be used to provide cold reservoirs for a nano-scale electronic device, and explore the limitations that would apply to such an experiment.

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2

Hewett, Nicholas Peter. "The electron-phonon interaction in a two dimensional electron gas." Thesis, University of Nottingham, 1988. http://eprints.nottingham.ac.uk/14218/.

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At low temperatures the predominant energy loss mechanism for a Joule-heated two dimensional electron gas (2DEG) in a metal oxide semiconductor field effect transistor (MOSFET) is by acoustic phonon emission. By very accurately measuring the temperature gradient developed along the silicon substrate the phonon emission has been investigated as a function of electron concentration, device power, magnetic field and temperature. In zero magnetic field the results show the cut-off predicted theoretically in the maximum phonon momentum that can be emitted in the plane of the 2DEG for low electron concentrations. It is also found that the momentum of the emitted phonons perpendicular to the plane of the 2DEG is restricted by the width of the 2DEG for the high resistivity (1000 [omega]cm) substrates used. For carrier concentrations greater than 4.9 x 1016 m-2 phonon emission from an upper subband is seen. Electrical measurements indicate that the high mobility (1.2 m2 V-1 S-1) of the devices used leads to changes in the screening of scattering potentials by the electrons being important. This is also seen in the phonon emission experiments. Experiments performed in quantising magnetic fields up to 7 T show that for the powers used (0.2 uW mm-2 – 500 uW mm-2) the phonons emitted arise from Lars-Landau level scattering. Oscillations in the temperature of a thermometer situated directly opposite the middle of the 2DEG are attributed to the movement of the phonon emission to the corners of the 2DEG when the Fermi level is between Landau levels (the Quantum Hall regime). Other trends are attributed to the width of the Landau level limiting the maximum phonon energy that can be emitted. Attempts to use a stress tuned phonon filter to probe the frequency dependence of the phonon emission failed due to experimental difficulties.

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3

Kettenis, Mark Martinus. "On the inhomogeneous magnetised electron gas." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2001. http://dare.uva.nl/document/60339.

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4

Papathomas, Paul Michael. "Developments in gas-phase electron diffraction." Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/12760.

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The first molecular scattering observed using the new Edinburgh electron diffraction apparatus is detailed in this thesis. The new apparatus utilises a phosphor screen/CCD detection system rather than the photographic plates more commonly used in electron diffraction studies. The electron beam is provided by a telefocus electron gun. Two molecular target sources have been investigated: a Campargue-type molecular beam and an effusive needle source. Calibration of the apparatus has been attempted using argon gas. Carbon tetrafluoride, CF₄, has been used as a typical gas-phase molecule and its scattering investigated extensively, while preliminary results for a more complex molecule, 1,2,4,5-tetrafluorobenzene, are also reported. Finally, the structure refinement of di-t-butyl(trichlorosilyl)phosphane using data from the existing electron diffraction apparatus is reported.

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5

Fender, Robert Scott. "Advances in gas-phase electron diffraction." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/14833.

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A new gas-phase electron diffraction apparatus is reported in this thesis. The machine complements the existing electron diffraction set-up at Edinburgh University. The new apparatus utilises an electron counting device consisting of a pair of stacked microchannel plates and a novel, position-sensitive anode counter rather than the photographic plate-rotating sector method more commonly used in electron diffraction studies. The work carried out with this detector is discussed together with results from a simulation program designed to evaluate the operational capabilities of the device under a range of experimental conditions. The molecular target source was provided by a Campargue-type molecular beam and the electron beam was produced by a telefocus electron gun. Both of these beams have been fully characterised and the results are presented in this work. A short review is given of the current developments in gas-phase electron diffraction. Finally, the structural refinements of two molecules studied using the photographic method are reported. These are 1,2-di-tert-butyldisilane and 1,2-dicarbapentaborane(7).

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6

Tovstyuk, C. C. "Thermodynamic Functions of Electron Gas in Strong anisotropic Materials. Quantum Gas." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42583.

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In this paper we report about the peculiarities of thermodynamic functions of quantum electron gas in layered crystals. In such materials the conductivity along the layers exceeds by several orders the conductivity across layers. To these structures depend layered materials: YTe3, LaTe3, CeTe3, InSe, which are considered at low temperatures, as well as a number of organic conductors. There are many theoretical and experimental papers, indicated coexistence of equipotential energy surfaces of electrons in the form of corrugated cylinders and corrugated sheets. The thermodynamic functions for quantum electron gas are evaluated and compared for two different dependences of energy on momentum. The same parameters are used in both models – they are effective masses and translation vectors for β - GaSe. Our investigations allowed explaining the temperature dependence of resistivity for strong anisotropic and isotropic crystals at law temperatures, received by experiment. We also analyzed the specific heat in such crystals and explained the anomaly, observed in such crystals and illustrated the imperfection of the Debye model.

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7

Drut, Joaquín E. "The unitary Fermi gas /." Thesis, Connect to this title online; UW restricted, 2008. http://hdl.handle.net/1773/9745.

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8

Leung, Ki Y. "Electron mobilities in binary rare gas mixtures." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29339.

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This thesis presents a detailed study of the composition dependence of the thermal and transient mobility of electrons in binary rare gas mixtures. The time independent electron real mobility in binary inert gas mixtures is calculated versus mole fraction for different electric field strengths. The deviations from the linear variation of the reciprocal of the mobility of the mixture with mole fraction, that is from Blanc's law, is determined and explained in detail. Very large deviations from the linear behavior were calculated for several binary mixtures at specific electric strengths, in particular for He-Xe mixtures. An interesting effect was observed whereby the electron mobility in He-Xe mixtures, for particular compositions and electron field strength could be greater than in pure He or less than in pure Xe. The time dependent electron real mobility and the corresponding relaxation time, in particular for He-Ar and He-Ne mixtures are reported for a wide range of concentrations, field strengths (d.c. electric field), and frequencies (microwave electric field). For a He-Ar mixture, the time dependent electron mobility is strongly influenced by the Ramsauer-Townsend minimum and leads to the occurrence of an overshoot and a negative mobility in the transient mobility. For He-Ne, a mixture without the Ramsauer-Townsend minimum, the transient mobility increases monotonically towards the thermal value. The energy thermal relaxation times 1/Pτ for He-Ne, and Ne-Xe mixtures are calculated so as to find out the validity of the linear relationship between the 1/Pτ of the mixture and mole fraction. A Quadrature Discretization Method of solution of the time dependent Boltzmann-Fokker-Planck equation for electrons in binary inert gas mixture is employed in the study of the time dependent electron real mobility. The solution of the Fokker-Planck equation is based on the expansion of the solution in the eigenfunctions of the Fokker-Planck operator.
Science, Faculty of
Chemistry, Department of
Graduate

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9

Hayes, Stuart A. "Development of experimental gas electron diffraction technique." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/2581.

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A state-of-the-art gas electron diffraction (GED) apparatus has been reassembled in the school of chemistry at the University of Edinburgh. This combines molecularbeam and telefocus-electron-gun technologies and the alignment of the electron beam produced by the latter has been discussed. A new custom-made CCD detector has also been installed and electron diffraction patterns for a few small molecules have been recorded. In analogy to the rotating sector in a conventional GED apparatus, the new camera contains an optical filter and a procedure for its calibration is outlined and followed step by step to produce an estimate of the filter transmittance. The data have been shown to be of less than ideal quality and the probable root of the problem is discussed. GED refinements of two pairs of compounds (arachno-6,9-decaboranes, and a covalent sulfonate and thiosulfonate) are presented, using data collected with the conventional Edinburgh GED apparatus.

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10

Vogt, Martin. "Spectral moments in the homogeneous electron gas." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615783.

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11

Chabasseur-Molyneux, Vincent Robert. "Ohmic contacts to the two dimensional electron gas of GaAs-A1GaAs heterostructures." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624719.

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12

Spink, Graham George. "Application of quantum Monte Carlo methods to homogeneous electron and electron-hole systems." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/275725.

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The properties of the macroscopic world around us, and of which we are a part, are largely determined by the low energy, collective behaviour of many interacting particles, including the nuclei and, especially, the electrons present. Although the fundamental laws governing the behaviour of these many-body systems are believed to be known in principle, the practical solution of the equations of quantum mechanics remains a challenging area of research. This thesis is concerned with the application of quantum Monte Carlo methods to two model systems: the spin-polarised homogeneous electron gas, and a hole-doped electron gas. Electronic structure theory is briefly reviewed before discussing in more detail the quantum Monte Carlo methods used in this thesis. A study of the three-dimensional spin-polarised homogeneous electron gas (HEG) is then reported, where the relatively new technique of twist averaging is investigated in detail and accurate energies and pair correlation functions are obtained over densities $r_s = 0.5 – 20$ a.u. and the full range of spin-polarisation, allowing comparison with the Perdew-Zunger interpolation scheme used in local spin density approximation exchange-correlation functionals. Following this, an impurity is added to the electron gas in the form of a positively charged hole, and the interaction is studied. Relaxation energies, pair correlation functions and momentum densities are reported. Trion formation is observed over a range of carrier densities and electron-hole mass ratios in agreement with experiment. Isolated trions are also studied, where the diffusion Monte Carlo method is exact. Methodological innovations developed while carrying out this work are discussed, including a variance reduction technique for twist-averaged calculations and a new trial wave function for impurity-in-HEG calculations.

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13

Tas, Murat. "Dielectric Formulation Of The One Dimensional Electron Gas." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604981/index.pdf.

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The charge and spin density correlations in a one dimensional electron gas (1DEG) confined in a semiconductor quantum wire structure at zero temperature are studied. The dielectric formulation of the many--body problem is employed and the longitudinal dielectric function, local-field correction, static structure factor, pair correlation function, ground state energy, compressibility, spin-dependent effective interaction potentials, paramagnon dispersion and static spin response function of the 1DEG are computed within the self-consistent field approximations of Singwi et al., known as the STLS and SSTL. The results are compared with those of other groups, and those obtained for two-dimensional electron gas systems whenever it is possible. It is observed that the SSTL satisfies the compressibility sum rule better than the STLS. Calculating the ground state energy of the 1DEG in unpolarized and fully polarized states, it is shown that both STLS and SSTL predict a Bloch transition for 1DEG systems at low electron densities. Finally, the coupled plasmon-phonon modes in semiconductor quantum wires are calculated within the Fermi and Luttinger liquid theories. The coupling of electrons to bulk longitudinal optical phonons without dispersion and to acoustic phonons via deformation potential with a linear dispersion are considered. Using the dielectric formalism, a unified picture of the collective coupled plasmon-phonon modes is presented. Considerable differences between the predictions of the Fermi and Luttinger liquid approaches at large wave vector values, which may be observed experimentally, are found.

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14

Leonard, Darren J. T. "Dynamical properties of the two-dimensional electron gas." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301235.

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15

Noble-Eddy, Robert. "Gas-phase electron diffraction studies of unstable molecules." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/4101.

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Gas-phase electron diffraction (GED) is the only viable technique for the accurate structural study of gas-phase molecules that contain more than ~10 atoms. Recent advances in Edinburgh have made it possible to study larger, more complex, stable molecules using the SARACEN method. This thesis is concerned with obtaining the structures of unstable species, using both standard GED techniques and by developing a new method in which ash vacuum pyrolysis is used to generate short-lived species in situ. In the first part of this thesis nine primary phosphines (R-PH2) with different substituents (R = methyl, vinyl, ethynyl, allenyl, allyl, propargyl, phenyl, benzyl and chloromethyl) are studied by GED. Vinylarsine and vinyldichloroarsine are also studied. Primary phosphines and arsines appear infrequently in the literature owing to their toxicity and high reactivity, especially of the unsaturated systems. The conformational behaviour in these molecules and trends throughout the series are rationalised. As appropriate, comparisons are made to analogous amines and the differences found are discussed. Tertiary phosphines (R3P) are routinely protected by complexation with borane (BH3) and it has been proposed that this technique could be extended to primary phosphines. As an extension of the initial investigation, the GED study of methylphosphine-borane offers an insight into structural changes that occur upon complexation, although attempts to study larger phosphine-borane complexes by GED proved dificult. The structures and bonding trends in a series of phosphineborane adducts are discussed, mainly using the results of ab initio calculations. The second part of the thesis details the implementation of a new, very high temperature nozzle, which allows the generation of short-lived species by pyrolysis. The workings of this nozzle are discussed and the study of the structure of ketene, generated from three different precursors, is detailed. The benzyl radical has also been studied, and a preliminary GED structure is presented. As a result of this work the molecular structures of Meldrum's acid and dibenzylsulfone are also presented, having been determined in the gas phase for the first time.

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16

McCaffrey, Philip D. "Equilibrium structures from gas-phase electron-diffraction data." Thesis, University of Edinburgh, 2007. http://hdl.handle.net/1842/2601.

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For the past 75 years gas-phase electron diffraction (GED) has remained the most valuable technique for determining structures of small molecules, free from intermolecular interactions. Throughout this period many improvements have been made to both the experimental and theoretical aspects of this technique, leading to the determination of more accurate structures. As the uncertainties associated with many stages of the process have been greatly reduced, errors introduced by assumptions, which were previously neglected, now play an important role in the overall accuracy of the determined structure. This work is focused on two such areas, namely the treatment of vibrational corrections and the vibrational effects on the scattering of individual electrons by multiple atoms. A novel method has been developed which allows the extraction of equilibrium structures (re) from distances obtained directly from GED experiments (ra). In unfavourable cases (such as small molecules with large-amplitude and / or highly anharmonic modes of vibration) traditional methods can introduce errors of comparable size to those obtained from the experiment. The newly developed method, EXPRESS (EXPeriments Resulting in Equilibrium StructureS), overcomes the problems which have plagued previous attempts through exploring a more extensive region of the potential-energy surface (PES), specifically regions relating to the normal modes of vibration. The method has been applied, initially, to sodium chloride in the gas phase as this contains dimer molecules with very low-frequency large-amplitude modes of vibration. The experimentally determined re structure gives good agreement with high-level ab initio calculations. Following this success, the EXPRESS method was then applied to sodium fluoride, sodium bromide and sodium iodide, giving similarly good agreement with theoretical calculations. The regular mixed alkali halide dimers (D2h symmetry) cannot be studied by microwave spectroscopy as they do not have a permanent dipole moment. However, vi mixed dimers (C2v) and asymmetric dimers (Cs) do not suffer from this constraint. Using insights learned from the ab initio studies of the sodium halides, geometries and dipole moments have been calculated for a range of mixed and asymmetric alkali halide dimers to enable their study by microwave spectroscopy. A multi-dimensional version of the EXPRESS method has been applied to the lowfrequency modes of chlorofluoroacetylene and chlorodifluoronitrosomethane to assess the effects of coupling between these modes of vibration in these structurally challenging systems. To obtain re structures of larger molecules a second method, using molecular dynamics (MD), has been developed and has been implemented on two test cases: the sodium chloride dimer and octasilsesquioxane. Traditional scattering theory used in GED employs the first-order Born approximation (FBO). However, this ignores any multiple scattering events, which are important for heavier atoms. Using a method similar in nature to EXPRESS a full vibrational analysis of three-atom scattering has been conducted on tellurium dibromide and tellurium tetrabromide.

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17

Ouali, Fatma Fouzia. "Phonon emission from a two dimensional electron gas." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293620.

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18

Al-Dubuni, M. H. "Electrical properties of the two dimensional electron gas." Thesis, University of St Andrews, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384581.

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19

Ensslin, Kasey Josephine 1982. "Gas electron multipliers in a time projection chamber." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/16901.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2003.
Includes bibliographical references (p. 71-73).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
by Kasey Josephine Ensslin.
S.B.

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20

Chan, Ho Bun 1969. "Tunneling spectroscopy of the two-dimensional electron gas." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9387.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1999.
Includes bibliographical references (p. 155-161).
We measure the single particle density of states (DOS) of a two-dimensional electron system (2DES) in a GaAs/AlGaAs heterostructure. Using a technique that we call "Time Domain Capacitance Spectroscopy" (TDCS), we measure the complete current-voltage characteristics for tunneling into the 2DES without making ohmic contacts to it. TDCS detects the tunneling current in regimes difficult to access by conventional methods, such as when the in-plane conductance is low. For the first time we detect the contributions of localized states to the tunneling current. The DOS of an interacting 2DES in the diffusive limit displays logarithmic energy dependence near the Fermi level. Using TDCS, we measure the voltage dependence of the tunneling conductance of a semiconductor 2DES and observe the logarithmic Coulomb anomaly for the first time in 2D systems other than thin metal films. As we increase the density, this suppression in tunneling conductance narrows and recedes. Nevertheless suppression reappears when we apply a magnetic field perpendicular to the 2D plane. We find that the tunneling conductance depends linearly on voltage near zero bias for all magnetic field strengths and electron densities. Moreover, the slopes of this linear gap are strongly field dependent. The data are suggestive of a new model of the tunneling gap in the presence of disorder and screening. We also use TDCS to study the interactions among electronic spins. By applying excitations less than kT, we observe that equilibrium tunneling into spin-polarized quantum Hall states (v=l, 3, 1/3) occurs at two distinct tunneling rates for samples of very high mobility. Some electrons tunnel into the 2DES at a fast rate while the rest tunnel at a rate up to 2 orders of magnitude slower. Such novel double-rate tunneling is not observed at even-integer filling fractions where the 2DES is not spin-polarized. The dependence of the two rates on magnetic field, temperature and tunnel barrier thickness suggests that slow in-plane spin relaxation, possibly related to formation of Skyrmions, leads to a bottleneck for tunneling of electrons.
by Ho Bun Chan.
Ph.D.

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21

Wan, Zhong. "Induced Superconductivity in Two Dimensional Electron Gas System." Thesis, Purdue University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10830652.

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Recently, interest in superconductor-semiconductor interfaces was renewed by the search for non-Abelian states. One of the possible platform is proximity induce superconductivity into an 1D semiconductor system with strong spin orbit (SO) interaction, such system is predicted to support Majorana excitation. Another candidate is superconductivity coupled to the edge of fractional quantum Hall state, in such system, higher order of non-Abelian statistics is predicted. With such non-Abelian states, topological quantum computing can be realized. In this thesis, I will discuss the approach made by us to investigate such system.

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22

Young, Stuart. "Towards gas-phase electron diffraction of novel species." Thesis, University of York, 2015. http://etheses.whiterose.ac.uk/11357/.

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Novel additions have been made to the York time-averaged electron diffractometer with a view to the study of low volatility and more exotic species. The telefocus electron gun present in the apparatus has been improved and the resulting beam width reduced from 0.76 to 0.40 mm. The existing data collection system was fully tested and eventually replaced with a custom designed camera assembly to improve data quality; this was further improved by the addition of a liquid nitrogen cold trap. For the study of lower-volatility compounds an air-heated nozzle assembly was built, which, paired with the high intensity of electrons produced from the telefocus gun and almost limitless data acquisition possible using the camera assembly, allows diffraction patterns to be collected from a smaller target density in the sample beam. Molecular dynamics simulations have been performed using Newton-X to provide vibrational corrections for refinements. These corrections allow a better description for large-amplitude and anharmonic motions, which are badly accounted for using current methods. These will be especially useful for the more complex molecules the apparatus has been designed to study. To extract and handle the diffraction data collected, custom software has been developed and tested. This software, combined with the improvements and additions to the apparatus, was used to refine the structure of 4-(dimethylamino)benzonitrile. The combination of these improvements to the apparatus and the custom software, will allow the structure determination of species such as carbon suboxide (C 3 O 2 ), and silyl chloride (SiH 3 Cl) dimers.

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23

Owen, J. A. "Effects of the relativistic correction to the electron mass on electron cyclotron current drive." Thesis, University of St Andrews, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370602.

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24

Ebrahimnejad, Rahbari Seyed Hadi. "Electrical measurement of spin-dependent resistivity in GaAs/AlGaAs two-dimensional electron gas." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/13900.

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The electrical transport in the semiconductor two-dimensional electron gases (2DEGs) in the presence of magnetic fields have been the subject of extensive experimental and theoretical studies. Whereas the experiments generally focus on the total magnetotransport of the spin-up and spin-down electrons, the problem of how individual spin components contribute to the sum has been mostly remained untouched. Due to the Zeeman splitting of the Fermi velocities, spin-up and spin-down electrons face different resistivities against their flow. In this thesis, this problem is addressed based on electrical generation and detection of nonequilibrium spin polarization in a narrow conducting channel of 2DEG in a GaAs/AlGaAs heterostructure. It makes use of narrow quasi-one-dimensional constrictions, known as quantum point contacts (QPCs), at a high magnetic field as the injector and detector of the spin polarization. We also simulate the problem based on an one-dimensional spin diffusion model and it turns out that it numerically agrees with the measurements using an electron spin susceptibility which is enhanced compared to that of bare GaAs. Such enhancements are generally linked with the electron-electron interactions which become important for electrons in confined geometries. The first section reviews the general characteristic properties of 2DEGs in GaAs/AlGaAs semiconductor heterostructures, gate-defined structures and quantized electrical transport through QPCs. The second chapter reviews the main results of electronic transport measurements on 2DEGs in the presence of in-plane magnetic fields, and the third chapter includes our spin polarization measurement results in a narrow channel of 2DEG and how they help to account for the effect of spin orientation on the electrical resistivity.

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25

Matthews, Paul. "The fabrication and measurement of a two-dimensional electron gas base hot electron transistor." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284193.

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26

Nunner, Tamara S., N. A. Sinitsyn, Mario F. Borunda, V. K. Dugaev, A. A. Kovalev, Ar Abanov, Carsten Timm, et al. "Anomalous Hall effect in a two-dimensional electron gas." American Physical Society, 2007. http://hdl.handle.net/2237/11243.

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27

Barker, D. R. "Frozen electron gas models for molecular dynamics of liquids." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596361.

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Methods for improving the size of accurate Kohn-Sham (KS) DFT calculations have often focused on embedding the KS calculation within a region of fixed electronic density. This thesis examines the potential for a similar type of approach within Car-Parrinello, ab-initio, Molecular Dynamics (CPMD). A frozen electron density (FED) model is incorporated into a KS-DFT based simulations of liquid water. Interactions between FED and KS species are determined using total energy expressions taken from the study of embedded systems. The initial step during this development was a study of the FED electron gas model proposed by Gordon and Kim for rare gas systems, using a modified version of the DL_POLY MD code. The adapted code was applied to investigate various options for extending this scheme to inter-molecular interactions in liquid water, including assessment of the suitability of a number of kinetic energy (KE) functionals. The optimisation of electron density for a FED model of water was explored semi-empirically, based on adaptation of the fixed molecular electron density to the condensed phase environment. Consistent with experience from force field methods, enhancement of the molecular dipole moment proved to be necessary to reproduce the properties of the liquid. Using the TF, PW01 and LLP KE functionals, models giving good agreement with experimental results were obtained. These each carried a dipole moment of 2.95 D, the same as has been observed by recent ab-initio MD studies based on fully self-consistent KS methods. Finally the CPMD code was adapted to incorporate these models into mixed KS/FED simulations, in which both molecular types occupied the same simulation cell. All MD runs showed energetic stability and good overall structure. However, more acceptable reproduction of the inter-molecular interactions of a fully KS-DFT calculation were obtained with the PW91 and LLP based models, than with that based on the TF functional. This is in agreement with similar calculations reported for the gas phase dimer.

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28

Carter, Paul James Anthony. "Acoustic phonon scattering by a 2 dimensional electron gas." Thesis, University of Nottingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329844.

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29

Cooper, John. "Phonon emission from a hot two-dimensional electron gas." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334781.

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30

Holwill, C. J. "Determination of molecular structure by gas-phase electron diffraction." Thesis, University of Reading, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380843.

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31

Wilkinson, Robert. "Plasmons in a grating-coupled two-dimensional electron gas." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386821.

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32

Dial, Oliver Eugene III. "Single particle spectrum of the two dimensional electron gas." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/45158.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2007.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 251-265).
Accurate spectroscopy has driven advances in chemistry, materials science, and physics. However, despite their importance in the study of highly correlated systems, two-dimensional systems (2DES) have proven difficult to probe spectroscopically. Typical energy scales are on the order of a millielectron volt (meV), requiring high resolution, while correlated states of interest, such as those found in the integer and fractional quantum Hall effect, are destroyed by excessive electron heating. Approaches based on tunneling have been hampered by problems such as ohmic heating and low in-plane conductivity, while optical approaches probe long-wavelength excitations which can be difficult to interpret. Here we present a refined spectroscopic technique, time domain capacitance spectroscopy (TDCS), with which we measure the single particle density of states (DOS) of a 2DES with temperature-limited resolution. In TDCS, sharp voltage pulses disequilibrate a metallic contact from a nearby 2DES, inducing a tunnel current. We detect this current by monitoring the image charge of the tunneled electrons on a distant electrode. No ohmic contact to the 2DES is required. The technique works when the 2DES is empty or has vanishing in-plane conductivity, as frequently occurs in studying the quantum Hall effect. Using TDCS, we perform unprecedentedly high resolution measurements of the DOS of a cold 2DES in GaAs over a range from 15 meV above to 15 meV below the Fermi surface. We provide the first direct measurements of the width of the single-particle exchange gap and single particle lifetimes in the quantum Hall system. At higher energies, we observe the splitting of highly excited Landau levels by spin polarization at the Fermi surface, demonstrating that the high energy spectrum reflects the low temperature ground state in these highly correlated systems. These measurements bring to light the difficult to reach and beautiful structure present far from the Fermi surface.
by Oliver Eugene Dial, III.
Ph.D.

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33

Shepherd, James John. "A quantum chemical perspective on the homogeneous electron gas." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608223.

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34

Elahi, A. "Plasma electrochemistry : electron transfer at the solid/gas interface." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1427871/.

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The ability to control redox reactions at the solid/gas interface is demonstrated for the first time, by considering gaseous flame plasma as an electrolyte. An innovative method to perform potentio-dynamic experiments in a liquid-free electrochemical system using flame plasma is described. This novel approach can help apply the well-established foundations of electrochemistry developed almost exclusively in liquids, to the new context of gas plasma. There are limited examples using plasmas as media to study redox reactions but no examples of voltammetry in the gas phase at true solid/gas interfaces. Successful electrochemical measurements are illustrated by doping the flame plasma with both inorganic and organic species, and recording distinct faradaic peaks at defined potentials in cyclic voltammograms. The sensitivity of the system is highlighted by the ability to distinguish between several amino acids, pinpointing specific functional groups. The most significant innovation responsible for these measurements is the development of a reference electrode able to function at temperatures over 1300 K. Extensive assessment of several materials has enabled the development and optimisation of a reference electrode, allowing an extension of the potential window to 10 V; an unprecedented value in electrochemistry. After careful experimentation and appropriate control experiments, the features observed are confirmed as specific reduction processes at the solid/gas interface. Undoubtedly, and perhaps expectedly, there are significant departures from the analogous process in condensed phases. The physical origin of these electrochemical signals is discussed and a framework of interpretation upon which a full mechanistic understanding can be based is provided. The scope of commercial and academic impact is extensive. Liquid-free electrochemistry presents access to a plethora of redox reactions, which lie outside potential limits defined by liquids. The prospect of new redox chemistries will enable new technological applications such as electrodeposition and electroanalysis, which have significant economic and environmental benefits.

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Sano, Noriaki. "Development of Gas Purification Technology by Selective Electron Attachment." Kyoto University, 1997. http://hdl.handle.net/2433/202297.

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36

Liu, Yangmingyue. "Scanning Electron Microscopy To Probe Working Nanowire Gas Sensors." OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1256.

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This study is dedicated to the implementing of Electron-Beam-Induced Current (EBIC) microscopy to study the behavior of metal oxide semiconducting (MOS) nanowire (NW) gas sensor in situ under exposure to different environment. First, we reported the development of a single nanowire gas sensor compatible with an environmental cell. The major component of the device we use in this study is a single SnO2 nanowire attached to an electron transparent SiN membrane (50-100 nm thick), which was used for mounting nanowire working electrodes and surface imaging of NW. First the NW's conductivity is investigated in different temperatures. Higher temperature is proved to cause higher conductivity of NW. We also found that often the Schottky barrier is formed at the nanowire's contacts with Au and Au/Cr electrodes. Then NW's responses to gas and electron beam (from SEM) are analyzed quantitatively by current measurement. Electron-Beam-Induced Current technique was introduced for the first time to characterize the conductivity behavior of the nanowire during the gas sensing process. Resistive contrast was observed in the EBIC image.

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Bowman, John V. "Transport in a confined two-dimensional electron gas with longitudinal potential variations." Virtual Press, 1995. http://liblink.bsu.edu/uhtbin/catkey/958798.

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Since the discovery of conductance quantization within a nanostnucture, investigations have sought out causes to conductance fluctuations beyond the established plateaus. The focus of this work is to show the fundamental effects upon conductance due to longitudinal potentials and double quantum boxes when confined by hardwall boundaries. A theoretical model based upon a tight-binding recursive tureen's function methodology was modified to incorporate potential barrier variations. A qualitative evaluation, as well as, explanation of the model's results and limitations is discussed.
Department of Physics and Astronomy

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38

Hughes, Ian G. "Electron ion and ion-ion collisions." Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335410.

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39

Barroy, Pierre ReneÌ Jean. "Electron kinetics in non-equilibrium plasmas." Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272394.

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40

Grumbling, Emily Rose. "Electronic Structure, Intermolecular Interactions and Electron Emission Dynamics via Anion Photoelectron Imaging." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/195933.

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This dissertation explores the use of anion photoelectron imaging to interrogate electronic dynamics in small chemical systems with an emphasis on photoelectron angular distributions. Experimental ion generation, mass selection, laser photodetachment and photoelectron imaging were performed in a negative-ion photoelectron imaging spectrometer described in detail. Results for photodetachment from the simplest anion, H⁻, are used to illustrate fundamental principles of quantum mechanics and provide basic insight into the physics behind photoelectron imaging from a pedagogical perspective. This perspective is expanded by introducing imaging results for additional, representative atomic and small molecular anions (O⁻, NH₂⁻ and N₃⁻) obtained at multiple photon energies to address the energy-dependence of photoelectron angular distributions both conceptually and semi-quantitatively in terms of interfering partial photoelectron waves. The effect of solvation on several of these species (H⁻, O⁻, and NH₂⁻) is addressed in photoelectron imaging of several series of cluster anions. The 532 and 355 nm energy spectra for H⁻(NH₃)n and NH₂⁻(NH₃)n (n = 0-5) reveal that these species are accurately described as the core anion solute stabilized electrostatically by n loosely coordinated NH3 molecules. The photoelectron angular distributions for solvated H⁻ deviate strongly from those predicted for unsolvated H⁻ as the electron kinetic energy approaches zero, indicating a shift in the partial-wave balance consistent with both solvation-induced perturbation (and symmetry-breaking) of the H⁻ parent orbital and photoelectron-solvent scattering. The photoelectron energy spectra obtained for the cluster series [O(N₂O)n]⁻ and [NO(N₂O)n]⁻ indicate the presence of multiple structural isomers of the anion cores, the former displaying sharp core-switching at n = 4, the latter isomer coexistence over the entire range studied. The photoelectron angular distributions for detachment from the O⁻(N₂O)n and NO⁻(N₂O)n isomers deviate strongly from those expected for bare O⁻ and NO⁻, respectively, in the region of an anionic shape resonance of N₂O, suggesting resonant photoelectron-solvent scattering. Partial-wave models for two-centered photoelectron interference in photodetachment from dissociating I₂⁻ is presented and discussed in the context of previous results. New time-resolved photoelectron imaging results for I₂⁻, for both parallel and perpendicular pump and probe beam polarizations, are presented and briefly discussed. Finally, new ideas and directions are proposed.

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Fröhlich, Bernd. "A strongly interacting two-dimensional Fermi gas." Thesis, University of Cambridge, 2011. https://www.repository.cam.ac.uk/handle/1810/252252.

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42

Riley, Susan Tania. "Combined two-dimensional electron gas and artificial spin ice structures." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/13973/.

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This thesis presents research into the electron transport properties of hybrid semiconductor / ferromagnetic structures. Periodic arrays of ferromagnetic stripes and artificial spin ice (ASI - arrays of geometrically frustrated nanomagnets) are patterned atop GaAs-AlGaAs wafers containing a two-dimensional electron gas (2DEG), and resistance measurements are performed under cryogenic temperatures and applied magnetic fields. The effects of piezoelectric strain on the transport properties of 2DEGs are investigated by comparing the resistances of magnetic and non-magnetic stripes patterned atop a 2DEG. Piezoelectric strain manifests itself as electric commensurability oscillations in the longitudinal resistance of a 2DEG. These oscillations are independent of temperature and are caused by stress acting upon the edges of the stripes. Transport measurements of combined 2DEG / ASI structures reveal the first observations of commensurability oscillations (COs) caused by ASI in the longitudinal resistance of a 2DEG. These oscillations are periodic on length-scales commensurate with the length of the individual nanomagnets that form the ASI. The COs are temperature dependent, but independent of the angle of applied magnetic field for our particular samples. Models based upon a Fourier analysis of Maxwell's equations help explain our results. This thesis also addresses the thermally-activated magnetization dynamics behaviour of ASI. We show exactly how the proportion of each vertex type changes as an ASI is heated, and moves from an ordered state to a ground state. We compare the results from two different alloys of PdFe and three different lattice spacings. The way in which arrays of ASI change to a ground state is dependent upon the material composition of the ASI, with little dependence upon the period of the ASI. A material with a large magnetization requires a higher temperature to cause any magnetic spins to flip, after which the ASI abruptly changes from an ordered state to a ground state.

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Tamm, Brian Paul. "Gas electron multipliers and a scanner for automated quality control." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32905.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2005.
Includes bibliographical references (p. 85-87).
The gas electron multiplier (GEM) is a novel charge amplification element for use in gaseous particle detectors. Because of their high gain ([approx.] 10⁵ when cascaded) and ability to withstand harsh radiation conditions, GEMs have been selected for use in the time projection chambers of the latest high-energy experiments, including COMPASS, STAR, and the planned ILC. Foil quality has been found to be critical for optimal GEM performance. If an irregularity in just one of the roughly 600, 000 amplification holes of a 10 x 10 cm GEM induces a spark discharge, the entire GEM is useless. Computer simulations have also shown that amplification behavior is strongly dependent on hole diameter and shape. To improve foil quality control, an automated scanner has been constructed to optically examine every hole in a GEM. The machine can measure each hole's outer copper diameter and inner Kapton diameter and locate and geometrically classify any foil imperfections. The scanner has been used to characterize GEMs recently manufactured by Tech-Etch. These scans indicate a general absence of etching defects, but measured diameter inhomogeneity may result in gain variations as large as i20% over the active foil area.
by Brian Paul Tamm.
S.B.

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44

Harland, Peter W. "Studies of gas phase electron, ion and atom collision processes." Thesis, University of Edinburgh, 1995. http://hdl.handle.net/1842/14990.

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The research papers submitted in this thesis describe experimental and theoretical investigations of particle collisions in which the projectiles have been electrons, ions and atoms, and the targets have been atoms and molecules. Non-reactive and reactive collisions have been studied in order to explore the fundamental nature of the collision event, to understand the dynamics, and to facilitate the determination of thermochemical parameters and reaction properties. The formation of positive and negative ions under single collision conditions as a function of electron impact energy has been investigated for small molecules and for molecular clusters. The measurement of accurate ionization efficiency curves and ionization thresholds has been achieved using custom designed near-monochromatic electron sources or analytical deconvolution. In many cases, detailed energy balancing has been attempted through the measurement of the recoil energies of fragment ions using retarding electric fields. Ionization mechanisms for associative and dissociative resonance electron capture and the formation of isomeric positive ions have been deduced. Thermochemical parameters, including electron affinities, ionization potentials, enthalpies of formation and bond dissociation energies, have been determined. Experiments in which the molecular targets were spatially oriented have shown, for the first time, that the mass spectrum and the ionization efficiency are orientation dependent. A theoretical model has been developed which accounts for the experimental measurements. Investigations of ion-molecule chemistry and non-reactive ion-molecule interactions have been carried out using a custom designed drift-tube mass spectrometer. It has been shown that isomeric ions can be distinguished by their ion transport properties and that the isomeric form of an ion-molecule reaction product ion can be directly measured. A theoretical model based on a generalised ion-helium interaction potential was developed which quantitatively accounted for the relative ion mobilities of a wide range of ions according to their physical properties.

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Schirlin, Julien T. "Targeting low vapour pressure compounds in gas-phase electron diffraction." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/11377.

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Gas-phase electron diffraction (GED) has remained the most valuable technique for the collection of structural information in the gas phase, for the last 70 years. Unfortunately, this structural technique had reached a limiting factor: the volatility of chemicals. Therefore this work aims to provide new ways to overcome both the kinetic and thermodynamic aspects of this problem by the adoption of a new nozzle design and by the use of a reservoir. The new nozzle extends the capabilities of gas electron diffraction to compounds with lower vapour pressures or with vaporisation rates not adequate for the existing GED experimental conditions. The shape of the new nozzle allows the user to operate at a lower vapour pressure by increasing the diffraction area. The design investigated is the slit type. It allows the electron beam diameter to be kept small, but permits the gas to emerge from a slit running parallel to the beam. Collected and simulated data have confirmed our intuition that the amplitudes will be affected slightly by the slit nozzle. Superimposing simulated and collected data allowed us to establish the profile of the gaseous output from the new design nozzle and shows that the count of electrons being diffracted increase 5.5 fold, with respect to the conventional nozzle. Gas-phase electron diffraction data have been collected and analysed for 2,5-dichlorothiophene and 3,4dichloro-1,2,5-thidiazole. An extensive series of ab initio calculations has also been undertaken on these molecules, together with 2,5-difluoro and 3,4-dichlorothiophene, allowing the accurate determination of their gas-phase molecular structures. The structures are compared to those of their parent compounds in order to assess the effects of halogen substitution on the rings.

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Truitt, Patrick A. "Measurement of coupling between the electron gas and nanomechanical modes." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7738.

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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.
Thesis research directed by: Dept. of Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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47

SanGiorgio, Paul. "Measuring Electron Gas Relaxation in Gold through Second Harmonic Generation." Scholarship @ Claremont, 2001. https://scholarship.claremont.edu/hmc_theses/136.

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In a thermally equilibrated system, electron behavior in a metal is described by the Fermi-Dirac equation. With ultrafast lasers, electrons can be excited into temporary distributions which are not described by the Fermi-Dirac equation and are therefore not at a well-defined temperature. These nonthermal distributions quickly equilibrate through two primary processes: electron-electron scattering and electron-phonon scattering. In most situations, these effects are unnoticeable, since they are completed within 5 ps. A probabilistic numerical model for electron-electron scattering is presented. The model is robust, scaleable, and requires only one parameter. The success of the model suggests future work on a similar electron-phonon scattering model, which would provide a complete description of the elctron distribution during thermalization. Once complete, this model can be tested by measuring the amount of second harmonic light generated by an ultrafast laser in a pump-probe experiment.

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48

Östling, Janina. "New Efficient Detector for Radiation Therapy Imaging using Gas Electron Multipliers." Doctoral thesis, Stockholm University, Medical Radiation Physics (together with KI), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-857.

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Currently film is being replaced by electronic detectors for portal imaging in radiation therapy. This development offers obvious advantages such as on-line quality assurance and digital images that can easily be accessed, processed and communicated. In spite of the improvements, the image quality has not been significantly enhanced, partly since the quantum efficiency compared to film is essentially the same, and the new electronic devices also suffer from sensitivity to the harsh radiation environment. In this thesis we propose a third generation electronic portal imaging device with increased quantum efficiency and potentially higher image quality.

Due to the parallel readout capability it is much faster than current devices, providing at least 200 frames per second (fps), and would even allow for a quality assurance and adaptive actions after each accelerator pulse. The new detector is also sensitive over a broader range of energies (10 keV - 50 MeV) and can be used to obtain diagnostic images immediately prior to the treatment without repositioning the patient. The imaging could be in the form of portal imaging or computed tomography. The new detector is based on a sandwich design containing several layers of Gas Electron Multipliers (GEMs) in combination with, or integrated with, perforated converter plates. The charge created by the ionizing radiation is drifted to the bottom of the assembly where a tailored readout system collects and digitizes the charge. The new readout system is further designed in such a way that no sensitive electronics is placed in the radiation beam and the detector is expected to be radiation resistant since it consists mainly of kapton, copper and gas.

A single GEM detector was responding linearly when tested with a 50 MV photon beam at a fluence rate of ~10¹⁰ photons mm^-2 s^-1 during 3-5 μs long pulses, but also with x-ray energies of 10-50 keV at a fluence rate of up to ~10⁸ photons mm^-2 s^-1. The electron transmission of a 100 μm thick Cu plate with an optical transparency of ~46% was found to be ~15.4%, i.e. the effective hole transmission for the electrons was about one third of the hole area. A low effective GEM gain is enough to compensate for the losses in converters of this dimension. A prototype for the dedicated electronic readout system was designed with 50 x 100 pixels at a pitch of 1.27 mm x 1.27 mm. X-ray images were achieved with a single GEM layer and also in a double GEM setup with a converter plate interleaved. To verify the readout speed a Newton pendulum was imaged at a frame rate of 70 fps and alpha particles were imaged in 188 fps. The experimental studies indicates that the existing prototype can be developed as a competitive alternative for imaging in radiation therapy.

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49

Mollart, T. P. "Electron emission processes in cold cathode thermal arcs." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5546/.

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In this Thesis the processes of electron emission from cathode electrodes are studied theoretically, and the applicability of these mechanisms to the non refractory cathodes that can be used to sustain thermal arcs was examined. Apparatus that was used to generate and manipulate thermal arcs along rail electrodes is described in this thesis. Techniques for driving arcs over polished sample electrodes with magnetic or aerodynamic forces are outlined. Scanning electron microscopy was used to study emission site formation on highly polished electrodes with a natural 2.5 nm oxide layer. Theoretical maximum electron current densities that can be extracted by the arc were calculated and these were used, in conjunction with information from the experimental work, to make estimates of the lifetime of emission spots that are seen on the cathode electrodes of thermal arc devices. The lifetime was found to be dependent on the arc velocity over a range of velocity values from 3 to 80 ms(^-1). The lifetime measured ranged from 2.4 µs to 0.024 µs. Experiments on arcs driven at a constant velocity using a combination of aerodynamic and magnetic forces showed that the formation of emission spots was independent of die applied external magnetic field. The presence of artificially grown copper (11) oxide layers, 50 nm and 100 nm thick, were found to influence the lifetime. The effect of the oxide layer was predicted using a simple model accounting for the change of resistance that such an oxide layer would be expected to cause. Additional experiments showed that the resistance of the arc was independent of the oxide layer thickness, as predicted by the model.

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McKitterick, David. "Phonon probing of magnetically quantised 2D electron systems." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359910.

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Dissertations / Theses on the topic 'Electron gas'

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