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Dissertations / Theses on the topic 'LEED (low energy electron diffraction)'

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Published: 4 June 2021

Last updated: 6 February 2022

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1

Moyses, Matthew. "Thermal vibrations and surface dipole moments for LEED from alkali adsorbate systems." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307750.

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2

Ma, King-man Simon. "Surface structure determination by Patterson inversion of multi-incidence leed IV-curves /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23621783.

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3

Ma, King-man Simon, and 馬勁民. "Surface structure determination by Patterson inversion of multi-incidence LEED IV-curves." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31226486.

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4

Stockford, Chloe Anne. "A structural analysis of H₂O on Cu{110} using a novel low flux Fibre-Optic LEED apparatus." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609230.

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5

Li, Hiu-lung, and 李曉隆. "Determination of atomic structure of Co/GaN(0001) surface by using LEED Patterson inversion and tensor LEED fitting." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46089263.

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6

Song, Weihong. "A real space approach to LEED computation with flexible local mesh refinement." Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B39849004.

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7

Song, Weihong, and 宋慰鴻. "A real space approach to LEED computation with flexible local mesh refinement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B39849004.

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8

Tsang, Wai-kan, and 曾衛勤. "Determine the atomic structure of a surface with mixed structure phases by using LEED Patterson function." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B30497115.

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9

Lam, King-cheong. "Direct determination of surface structures of C2H4 and C2H2 on si(100) by LEED Patterson inversion." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41633830.

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10

Lau, Wai-ping. "Direct determination of the 6H-SiC(0001)-3X3 and 6H-Sic(0001)-[square root] 3 x [square root] 3 surface reconstruction by LEED Patterson function." Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B31367847.

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11

Rufe, Eric. "Assessing the Reactive Surface Area of Phlogopite during Acid Dissolution: An Atomic Force Microscopy, X-ray Photoelectron Spectroscopy, and Low Energy Electron Diffraction Study." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/31837.

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The behavior during dissolution of edge and basal surfaces of the mica phlogopite were examined using in situ atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS) and low-energy electron diffraction (LEED) in an attempt to characterize the reactive surface area during dissolution. Mica minerals are the ideal material for this study because they offer a high degree of structural anisotropy. Therefore surfaces with different structures are easily identified. Dissolution is shown to proceed preferentially by removal of material from {hk0} edges. Dissolution rates were calculated by measuring the volume of material removed from etch pits, and normalizing to either the â reactiveâ surface area of {hk0} edges exposed at pit walls, or to a total â BET-equivalentâ surface area. Rates normalized to total surface area are in the range of dissolution rates reported in the literature. Edge surface normalized rates are about 100 times faster. Long-term in situ AFM observations of phlogopite dissolution reveal that exposed (001) surfaces also display a distinct reactivity, though it operates on a different time scale. The top layer is shown to expand between 39 and 63 hours in contact with pH 2 HCl solution. Subsequent LEED analysis shows that the (001) surface becomes amorphous upon reacting with pH 2 HCl. Compositional characterization of the phlogopite after reaction shows that for pitted phlogopite surfaces, dissolution is characterized by leaching of octahedral cations and polymerization of the silica-enriched residual layer. No chemical changes or polymerization are observed for freshly cleaved unpitted phlogopite after reaction with pH 2 HCl for 24 hours. This suggests a gallery access mechanism is facilitated by edge attack, and is only significant on exposed (001) surfaces after a certain amount of dissolution by edge attack.<br>Master of Science

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12

Lau, Wai-ping, and 劉偉平. "Direct determination of the 6H-SiC(0001)-3X3 and 6H-Sic(0001)-[square root] 3 x [square root] 3 surface reconstruction by LEED Pattersonfunction." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31367847.

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13

Busayaporn, Wutthikrai. "TiO2(110) surface structure." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/tio2110-surface-structure(9641eaab-818a-4928-a0b2-78312de050d5).html.

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In this thesis three studies of the geometric structure of the (110) surface of single crystal rutile TiO2 are presented. Firstly, quantitative low energy electron diffraction (LEED-IV) data acquired from TiO2(110)(1x1) are reanalysed to confirm the integrity of the previously reported optimized geometries by performing structural optimisation as a function of depth into the selvedge. The second study addresses the geometry of the x-linked (1x2) reconstruction of the same surface. Again, LEED-IV data are analysed to quantitatively determine the surface structure. Part of this effort involved substantial development of the code (SATLEED) employed for simulating the experimental data, to allow simultaneous optimisation of more than one surface termination. In contrast to recent scanning probe work, the analysis indicates that the surface consists of two differently relaxed Ti2O3 added rows. The last study concerns ab initio calculations of the structure of benzoate on TiO2(110)(1x1). Of particular interest is the impact of surface coverage on the orientation of the benzene ring. It is predicted that the benzene ring twists and tilts away from high symmetry with increasing coverage due to adsorbate-adsorbate interactions. No evidence is found to support the formation of benzoate dimers or trimers, as was concluded in earlier experimental work.

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14

Lam, King-cheong, and 林景昌. "Direct determination of surface structures of C2H4 and C2H2 on si(100)by LEED Patterson inversion." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41633830.

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15

Mannsfeld, Stefan. "Ordering in weakly bound molecular layers: organic-inorganic and organic-organic heteroepitaxy." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1098888571984-95956.

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It is an aim of this work to provide insight into the energetic influence on the ordering of molecular thin films on crystalline substrates. Here, the term substrate either refers to inorganic crystal surfaces or highly ordered layers of another organic molecular species. In order to calculate the total interface potential of extended molecular domains, a new calculation technique (GRID technique) is developed in the first part of this work. Compared to the standard approach, this method accelerates the potential calculation drastically (times 10000). The other parts of the thesis are dedicated to the comparison of experimental results (obtained by scanning tunneling microscopy and electron diffraction) to the optimal layer structure as predicted by optimization calculations. Potential calculations which are performed for the system perylenetetracarboxylicdianhydride (PTCDA) on graphite demonstrate that point-on-line coincident structures correspond to energetically favorable alignments of the molecular lattice with respect to the substrate lattice. The capability of the GRID technique to predict the optimal layer structure is demonstrated for the system peri-hexabenzocoronene (HBC) on graphite. The organic-organic heteroepitaxy system PTCDA on HBC on graphite is investigated in order to clarify to which extent the ordering mechanism there differs from that of the organic-inorganic heteroepitaxy system PTCDA on graphite. As a result of this investigation, a new type of epitaxy, i.e., substrate induced ordering is found. This new epitaxy type is governed by the inner structure of the substrate lattice unit cell. Here, the substrate surface is a layer of organic molecules itself, hence the substrate surface unit cell does indeed exhibit a complex inner structure. A generalized classification scheme for epitaxial growth incorporating this new type of epitaxy is proposed. In the last chapter, the structure of the first layers of titanylphthalocyanine (TiOPc) on Au(111) is investigated and compared to potential optimization calculations. The correspondence of experimental and theoretical results provides evidence that the GRID technique can, in principle, also be applied to molecular layers on metal surfaces<br>Das Ziel der vorliegenden Arbeit ist es, Einblicke in die energetischen Einflüsse, die zur Ausbildung der Schichtstruktur organischer Moleküle auf kristallinen Substraten führen, zu geben. Diese Substrate sind entweder Oberflächen anorganische Kristalle oder selbst hochgeordnete Molekülschichten. Um das totale Grenzflächenpotential ausgedehnter Moleküldomänen berechnen zu können, wird im ersten Teil der Arbeit eine neue Berechnungsmethode (GRID Technik) vorgestellt. Im Vergleich mit herkömmlichen Berechnungsmethoden auf der Basis molekülmechanischer Kraftfelder ist diese neue Methode daher um ein Vielfaches schneller (Faktor 100000). Die folgenden Teile der Arbeit sind dem Vergleich experimenteller Ergebnisse (Rastertunnelmikroskopie und Elektronenbeugung) mit, durch Potentialoptimierungsrechnungen als energetisch günstig vorhergesagten, Schichtstrukturen gewidmet. So kann für das System Perylentetracarbonsäuredianhydrid (PTCDA) auf Graphit mittels Potentialberechnungen nachgewiesen werden, daß die experimentell gefundenen ?Point-on-line koinzidenten? Strukturen energetisch günstige Anordnungen des Molekülgitters bezüglich des Substratgitters darstellen. Die Eignung der neuen Berechnungsmethode zur Vorhersage der günstigsten Adsorbatgitterstruktur für ein gegebenes System aus Molekül und Substrat, wird anhand des Systems peri-Hexabenzocoronen (HBC) auf Graphit demonstriert. Das organisch-organische Heteroepitaxiesystem PTCDA auf HBC auf Graphit wird untersucht, um zu klären, inwieweit sich die dafür gültigen Ordnungsmechanismen von denen unterscheiden, die für das Wachstum des organisch-anorganischen Heteroepitaxiesystems PTCDA auf Graphit verantwortlich sind. Dabei gelingt es, eine bisher nicht klassifizierte Art von Epitaxie, d.h. substratinduzierter Ordnung, nachzuweisen. Dieser neue Epitaxietyp ist bedingt durch die innere Struktur einer Substrateinheitszelle - das Substrat ist ja hier selbst eine Schicht geordneter Moleküle, die natürlich eine innere Struktur aufweisen. Im folgenden wird ein verallgemeinertes Klassifizierungssystem für Epitaxietypen abgeleitet, welches den neuen Epitaxietyp beinhaltet. Im letzten Kapitel wird die Struktur von der ersten Lagen von Titanylphthalocyanin (TiOPc) auf Au(111) experimentell untersucht und mit entsprechenden Potentialoptimierungsrechnungen verglichen. Die Übereinstimmung von experimentellen und theoretischen Ergebnissen zeigt, daß die GRID Technik, zumindest prinzipiell, auch für Molekülschichten auf Metallsubstraten anwendbar ist

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16

Oh, Doogie. "Low-energy electron diffraction effects at complex interfaces." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28236.

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Thesis (M. S.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009.<br>Committee Chair: Thomas Orlando; Committee Member: Joseph Perry; Committee Member: Nicholas Hud; Committee Member: Phillip First; Committee Member: Rigoberto Hernandez.

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17

Mapledoram, Leigh David. "Quantitative surface structural determination by low energy electron diffraction." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338267.

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18

Pinkava, Pavel. "Theory of low energy electron diffraction for stepped surfaces." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46507.

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19

Forker, Roman. "Electronic Coupling Effects and Charge Transfer between Organic Molecules and Metal Surfaces." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-26163.

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We employ a variant of optical absorption spectroscopy, namely in situ differential reflectance spectroscopy (DRS), for an analysis of the structure-properties relations of thin epitaxial organic films. Clear correlations between the spectra and the differently intense coupling to the respective substrates are found. While rather broad and almost structureless spectra are obtained for a quaterrylene (QT) monolayer on Au(111), the spectral shape resembles that of isolated molecules when QT is grown on graphite. We even achieve an efficient electronic decoupling from the subjacent Au(111) by inserting an atomically thin organic spacer layer consisting of hexa-peri-hexabenzocoronene (HBC) with a noticeably dissimilar electronic behavior. These observations are further consolidated by a systematic variation of the metal substrate (Au, Ag, and Al), ranging from inert to rather reactive. For this purpose, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) is chosen to ensure comparability of the molecular film structures on the different metals, and also because its electronic alignment on various metal surfaces has previously been studied with great intensity. We present evidence for ionized PTCDA at several interfaces and propose the charge transfer to be related to the electronic level alignment governed by interface dipole formation on the respective metals<br>Zur Analyse der Struktur-Eigenschafts-Beziehungen dünner, epitaktischer Molekülfilme wird in situ differentielle Reflexionsspektroskopie (DRS) als Variante der optischen Absorptionsspektroskopie verwendet. Klare Zusammenhänge zwischen den Spektren und der unterschiedlich starken Kopplung zum jeweiligen Substrat werden gefunden. Während man breite und beinahe unstrukturierte Spektren für eine Quaterrylen (QT) Monolage auf Au(111) erhält, ist die spektrale Form von auf Graphit abgeschiedenem QT ähnlich der isolierter Moleküle. Durch Einfügen einer atomar dünnen organischen Zwischenschicht bestehend aus Hexa-peri-hexabenzocoronen (HBC) mit einem deutlich unterschiedlichen elektronischen Verhalten gelingt sogar eine effiziente elektronische Entkopplung vom darunter liegenden Au(111). Diese Ergebnisse werden durch systematische Variation der Metallsubstrate (Au, Ag und Al), welche von inert bis sehr reaktiv reichen, untermauert. Zu diesem Zweck wird 3,4,9,10-Perylentetracarbonsäuredianhydrid (PTCDA) gewählt, um Vergleichbarkeit der molekularen Filmstrukturen zu gewährleisten, und weil dessen elektronische Anordnung auf verschiedenen Metalloberflächen bereits eingehend untersucht worden ist. Wir weisen ionisiertes PTCDA an einigen dieser Grenzflächen nach und schlagen vor, dass der Ladungsübergang mit der elektronischen Niveauanpassung zusammenhängt, welche mit der Ausbildung von Grenzflächendipolen auf den entsprechenden Metallen einhergeht

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20

Wagner, Christian. "Potential Energy Minimization as the Driving Force for Order and Disorder in Organic Layers." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-38242.

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The topic of this work is the structural characterization and theoretical modeling of organic single and heterolayers. The growth of sub-monolayers and monolayers (ML) of the two polycyclic aromatic hydrocarbons quaterrylene (QT) and hexa-peri-hexabenzocoronene (HBC) on Ag(111) and Au(111) was investigated. A transition from a disordered, isotropic phase to an ordered phase with increasing coverage was found. The lattice of the ordered phase turned out to be coverage dependent. The intermolecular potential was modeled including Coulomb and van der Waals interaction by a force-field approach. The postulated repulsive character of the potential could be connected to the non-uniform intramolecular charge distribution and to a screening of the van der Waals forces. Furthermore, the influence of the variable lattice constant on the epitaxial growth of HBC was studied. The second part of this work deals with a ML of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on a ML of HBC. In dependency on the initial lattice constant of HBC, a total of three line-on-line (LOL) and point-on-line coincident phases of PTCDA (with respect to HBC) was found. Following an analysis of the general properties of LOL coincident systems via force-field calculations, a new method to predict the structure of such systems is introduced<br>Thema dieser Arbeit ist die strukturelle Charakterisierung von organischen Einfach- und Heterolagen sowie deren theoretische Beschreibung und Modellierung. Es wurden Submonolagen und Monolagen (ML) der polyzyklischen Kohlenwasserstoffe Quaterrylen (QT) und Hexa-peri-hexabenzocoronen (HBC) auf Ag(111) und Au(111) Einkristallen untersucht und ein Übergang von einer ungeordneten, isotropen Phase zu einer geordneten Phase mit steigender Bedeckung beobachtet. Die geordnete Phase wies dabei bedeckungsabhängige Gitterkonstanten auf. Das intermolekulare Potential wurde unter Berücksichtigung von Coulomb und van der Waals Anteilen mittels Kraftfeldmethoden modelliert. Der postulierte repulsive Charakter des Potentials konnte auf die Ladungsverteilung im Molekül und eine Abschwächung des van der Waals Potentials zurückgeführt werden. Weiterhin wurde der Einfluss der variablen HBC Gitterkonstante auf die epitaktische Relation des Gitters zum Metallsubstrat untersucht. Der zweite Teil der Arbeit widmet sich der Untersuchung einer ML 3,4,9,10-Perylenetetracarboxylic dianhydrid (PTCDA) auf einer ML HBC. Dabei wurden, in Abhängigkeit von der HBC Gitterkonstante, insgesamt drei verschiedene Typen von line-on-line bzw. point-on-line Epitaxie nachgewiesen. Im Anschluss an eine Analyse der generellen Eigenschaften solcher epitaktischer Lagen mittels Kraftfeldrechnungen wird eine neue Methode zur Vorhersage der Struktur konkreter Systeme vorgestellt

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21

Menzel, Andreas. "Step dynamics measurements with time-resolved low energy electron diffraction." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/27870.

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22

Meier, Matthias. "Influence de la liaison chimique sur la structure des surfaces d'alliages métalliques complexes." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0257/document.

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Un alliage métallique complexe est un intermétallique dont la maille est constituée d'un nombre important d'atomes et dont la structure peut être souvent décrite comme un empilement de motifs d'atomes reliés par des liaisons de type covalent. Al5Co2 est l'un de ces composés et est un catalyseur potentiel pour la semi-hydrogénation d'acétylène. L'influence de la structure tridimensionnelle sur les surfaces bidimensionnelles et donc la réactivité est étudiée. Pour se faire, le système massif est analysé en utilisant la DFT afin d'éclaircir ses propriétés thermodynamiques, électroniques et vibrationnelles. Les valeurs calculées, expérimentales et celles de la littérature sont en bon accord. La structure des surfaces de bas indice, (001), (100) et (2-10) est étudiée. Une combinaison de techniques d'analyse de surface sous ultra-vide - LEED, STM - et de DFT est utilisée pour les déterminations structurales. Les résultats indiquent que: (i) la structure des surfaces dépend des conditions de préparation, comme la température de recuit, (ii) la structure des surfaces peut être interprétée comme étant constituée de motifs tronqués où certaines liaisons de type covalent sont brisées. Les sites et les énergies d'adsorption des molécules impliquées dans la réaction de semi-hydrogénation sont calculés pour les trois surfaces. Pour les sites favorables, des distances spécifiques entre atomes d'hydrogène adsorbés et atomes de Co de surface et de sous-surface peuvent être observées. Les atomes de Co de sous-surface ont un caractère donneur d'électrons, stabilisant les atomes adsorbés en surface. En se basant sur des calculs NEB, de possibles chemins réactionnels sur la surface (2-10) sont proposés. L'activité calculée est similaire à celle obtenue pour la surface d'Al13Co4, qui est considérée comme un bon catalyseur. La sélectivité - la compétition entre la désorption d'éthylène et son hydrogénation en éthyle - est discutée<br>A complex metallic alloy is an intermetallic with a large unit cell and whose structure can often be seen as a stacking of motifs of strongly covalent-like bonded atoms. Al5Co2 is such a compound and is a potential catalyst for the semi-hydrogenation of acetylene. The influence of the 3-dimensional structure on 2-dimensional surfaces is investigated. Therefore, the bulk system is analysed using DFT to gain insight in the thermodynamic, electronic and vibrational properties. Good agreements between calculated results, experimental ones and results found in the literature are obtained. The low index (001), (100) and (2-10) surfaces are investigated. A combination of surface analysis techniques under ultra high vacuum - LEED, STM - and DFT calculations is used for the structural investigations. The results show that: (i) the surface structure depends on the preparation conditions, such as the annealing temperature, (ii) the surface structure can be interpreted as truncated motif parts, where the covalent-like bonds are broken. Adsorption sites and energies of molecules involved in the semi-hydrogenation reaction are calculated for all three surfaces. For favourable adsorption sites, specific distances of adsorbed H atoms with Co surface and subsurface atoms are observed. These Co subsurface atoms have an electron donor character, stabilising the adsorbed atoms at the surface. Based on NEB calculations, possible reaction paths on the (2-10) surface are proposed. The calculated activity is similar to the one obtained for the Al13Co4 surface, which is considered a good catalyst. The selectivity - the competition between desorption of ethylene and its further hydrogenation - is discussed

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23

Chandavarkar, Sumant. "Low-energy electron diffraction study of potassium adsorbed on nickle(111)." Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279665.

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24

Puisto, Sakari Rainer. "Surface crystallography of complex structures studied by low energy electron diffraction." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616126.

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25

Lee, Chiwon [Verfasser], and R. J. Dwayne [Akademischer Betreuer] Miller. "Development of Ultrabright Electron Sources and Time-Resolved Low-Energy Electron Diffractometer (LEED) / Chiwon Lee ; Betreuer: R.J. Dwayne Miller." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2019. http://d-nb.info/1199539163/34.

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26

何永健 and Wing-kin Ho. "The (3x3) reconstruction of SIC(0001): a low energy electron diffraction study." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31215300.

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27

Wang, Jian. "Low energy electron diffraction studies of transition metal oxide surfaces and films." [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975602977.

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28

Ho, Wing-kin. "The (3x3) reconstruction of SIC(0001) : a low energy electron diffraction study /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19737105.

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29

Titmuss, Simon. "A new approach to surface structure determination by low energy electron diffraction." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621553.

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30

朱翠屛 and Tsui-ping Chu. "Diffraction and direct methods for surface structure determination." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B3121406X.

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31

Chu, Tsui-ping. "Diffraction and direct methods for surface structure determination /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18933865.

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32

Müller-Rösch, Melanie [Verfasser]. "Femtosecond low-energy electron imaging and diffraction using nanotip photoemitters / Melanie Müller-Rösch." Berlin : Freie Universität Berlin, 2017. http://d-nb.info/1136319301/34.

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33

Cai, Aiguo. "Study of surface flattening kinetics by low energy electron diffraction on rutile(110)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ57094.pdf.

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34

Lai, Wai-kong Pan, and 黎偉江. "Low energy electron diffraction from SI(111)7X7 and ultrathin films onsubstrate crystals." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31221075.

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35

Rous, Philip James. "Dynamical theories of low energy electron diffraction from disordered and complex reconstructed surfaces." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38149.

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36

吳子傑 and Tsz-kit Victor Ng. "Inversion of low energy electron diffraction IV spectra of reconstructed structure of SiC (0001)." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31225007.

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37

Ng, Tsz-kit Victor. "Inversion of low energy electron diffraction IV spectra of reconstructed structure of SiC (0001)." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23234283.

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38

Lai, Wai-kong Pan. "Low energy electron diffraction from SI(111)7X7 and ultrathin films on substrate crystals /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20979071.

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39

Gladh, Jörgen. "Scanning Tunneling Microscopy and Low-Energy Electron Diffraction Studies of Quantum Wires on Si(332)." Thesis, Karlstad University, Faculty of Technology and Science, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-378.

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<p>In this master thesis I have investigated one-dimensional nanostructures, so called quantum wires. The goal was to grow them in situ on a stepped silicon surface and thereafter do several kinds of measurements, like Scanning Tunneling Microscopy, Low-Energy Electron Diffraction and Photoemission. The surface that was used was a Si(332) surface and the metals used in the growth of the quantum wires were gold and silver.</p><p>After the preparation and measurement of the stepped surface, evaporation of silver and gold was performed. The Scanning Tunneling Spectroscopy measurments were done on both Ag/Si(332) and Au/Si(332) surfaces. This gave information about the local density of stats on the surfaces and possible bandgaps.</p><p>All experiments were performed in ultra high vacuum, except the sample cutting and the first cleaning of the surface, which was done after the Shiraki method.</p>

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Leung, Wai-yan, and 梁偉恩. "Structure determinations of SnO₂ and TiO₂ surfaces by low energy electron diffraction Patterson inversion method." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50434524.

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The Tin dioxide (SnO2) and Titanium dioxide (TiO2) are very promising materials in Material science. The SnO2 is commonly used as a gas sensor while the TiO2 is used as a catalyst in many reactions. Despite of the usefulness of these two substances, their surface structures lack detail investigations in the previous years. The Low Energy Electron Diffraction (LEED) technique is commonly used to characterize surfaces in the past 40 years, it is a mature system that many researches rely on its result. However, structural analysis in LEED requires comparison with computational results based on pre-defined structure models, which is a time-consuming method and the results are not guaranteed to be found. The direct determinations of structure by Patterson function inversion methods introduced by Huasheng Wu and S. Y. Tong could provide a different path to search for surface structure. In the Patterson function, each maximum in the function corresponds to a relative position vector of atomic pairs. Multiple-angle-incident LEED has to be performed to obtain an artifact-free Patterson function. Serveal SnO2 and TiO2 surfaces have been characterized by LEED and Patterson function inversion. SnO2 (110), (100), (101) , Rutile TiO2 (110), Anatase TiO2 (110) have been prepared by argon ion sputtering and annealing cycles and the cleanness has been checked by Auger Electron Spectroscopy and LEED. Reconstruction is observed based on the study of the LEED patterns. SnO2 (110) surface shows a 4 x 1 reconstruction in UHV environment while it gives 1 x 1 under annealing in oxygen and C(2 x 2) at higher annealing temperature afterward. SnO2 (100) , (101) and Rutile TiO2 (110) surfaces show 1 x 1 reconstruction in UHV environment and the reconstruction persists for further annealing. The Anatase TiO2 (110) surface shows a 3 x 4 reconstruction in UHV environment. The 3 x 4 reconstruction of Anatase TiO2 (110) surface would raise research interests as it is quite a special reconstruction. Multiple-angle-incident LEED has been performed on the SnO2 (100), (101) and Rutile TiO2 (110) surfaces. Patterson function inversion is performed on the surfaces SnO2 (100) and Rutile TiO2 (110) . Only LEED is performed on SnO2 (110) , (101) and Anatase TiO2 (110) surfaces. From Patterson functions analysis, the surface atoms positions are determined for the surface SnO2 (100) and Rutile TiO2 (110). The results show that their reconstructions are negligible, but they have obvious relaxations.<br>published_or_final_version<br>Physics<br>Master<br>Master of Philosophy

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Bandak, Dmytro, та Dmytro Bandak. "Electron Dynamics with Core Level Spectroscopy in MgₓZn₁₋ₓO and SnS₂. Design of a Low Energy Electron Diffraction Instrument". Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/621456.

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This thesis consists of two distinct parts: Firstly, a core level spectroscopy study of SnS₂ and ternary oxide MgₓZn₁₋ₓO; secondly, the design and assembling of low electron energy diffraction instrument. In the former, the electronic structure and dynamics are investigated. In the study of the ternary oxide MgₓZn₁₋ₓO, the main goal was to better understand the influence of alloying MgO and ZnO as a method of bandgap engineering of ZnO. In the case of SnS₂, the focus of the investigation were the electronic properties of the material related to its layered structure as a source of both new fundamental physics and applications. The second part of the thesis describes the principles of design of the LEED instrument, its current functionality, operational instructions, and suggested further modifications for expanding its applications.

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Pang, Angbo. "Mass transport during step motion on the Si(111) (1x1) surface studied by low energy electron microscopy /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202009%20PANG.

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蘇偉基 and Wai-kei So. "Surface structure determination of Ga/Si (111) 3x3-R30 by Kikuchi electron holography." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31226693.

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So, Wai-kei. "Surface structure determination of Ga/Si (111) 3x3-R30 by Kikuchi electron holography /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23621588.

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Haynes, Matthew, and n/a. "Low Energy (e,2e) Studies of Inner Valence Ionization." Griffith University. Centre for Quantum Dynamics, 2002. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050902.142912.

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This thesis presents a series of electron impact ionization measurements on the gas phase targets of argon and krypton. The (e,2e) coincidence technique has been employed to measure the triple differential cross section (TDCS) using a new coincidence spectrometer designed to operate in the low energy regime (2 to 5 times the ionization energy) and in the coplanar geometry. The spectrometer is a conventional device utilizing a non-energy selected electron gun and two 1800 hemispherical electron analysers fitted with channel electron multipliers for detection of the outgoing electrons. A series of TDCS measurements were performed on the 3s inner-valence and 3p valence orbitals of argon employing coplanar asymmetric kinematics. Measurements for both orbitals were performed at an incident energy of 113.5 eV, ejected energies of 10, 7.5, 5 and 2 eV and a scattering angle of -15°. The energy of the scattered electron in each case was chosen to satis~' energy conservation and is dependent on the ionization energies of the different orbitals. The experimental cross sections are compared to theoretical TDCS calculations using the distorted wave Born approximation (DWBA) and variations of the DWBA in an attempt to investigate the role that post collisional interaction (PCI), polarization and electron exchange play in describing the TDCS in the low energy regime. To further extend this analysis, a series of TDCS measurements were performed on the 3s and 4s. orbitals of argon and krypton, respectively, employing coplanar symmetric kinematics. Measurements were performed for the 3s orbital at outgoing energies of 50, 20, 10 and 4eV and for the 4s orbital at outgoing energies of 85, 50, 20 and 10 eV. The kinematics were chosen to coincide with several of the (e,2e) measurements made in the same geometry on the 3p orbital of argon by Rouvellou et al (1998). The experimental results were again compared to a DWBA calculation and similar variations to those employed for the asymmetric measurements.

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Holmes, Daniel John. "Surface structure determination by surface extended X-ray absorption fine structure and low energy electron diffraction." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235773.

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Yang, Yang, and 楊暘. "Atomic structure studies of zinc oxide (0001) polar surface by low energy electron diffraction at multiple incident angles." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48199515.

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Zinc oxide surfaces have been of considerable interest because of their favorable properties, such as high electron mobility, good transparency, large electronic breakdown field and wide bandgap. Knowing the surface structure of ZnO is the key to better understand the above phenomena and to further develop its applications. In this thesis, the Patterson Function was evaluated by inversion of LEED I-V spectra at multiple incident angles to determine the surface structure of the ZnO(0001) polar surface. The sample was prepared by degassing and then 15 cycles of argon sputtering and annealing. The experimental LEED I-V spectra from multiple incident angles were taken from the sample. After processing the data by a macro program in OPTIMAS and a Matlab program, a clean Patterson Function map showing the inter-atomic pair distances was obtained. It was then compared with the simulated Patterson Function map of the proposed 1×1 bare surface model. As a result, the spots positions in the simulated Patterson Function map matched well with that of the experimental Patterson Function map. On the other hand, the LEED I-V curve fitting work was done by the surface science group of City University of Hong Kong. Six models were proposed by them and normal incidence theoretical LEED I-V spectra were calculated to fit with the experimental LEED I-V curves provided by us. Among the six models 2×2 Zn point defect model was fitted to be the best model with the R-factor 0.244. We also compared the multiple scattering simulated Patterson Function map of 2×2 Zn point defect model with the experimental one to verify the validity of the model. As a result, the model fit the experimental data. So we conclude that in general 1×1 model support the order part, and 2×2 top layer Zn defect model best fits the random missing part.<br>published_or_final_version<br>Physics<br>Master<br>Master of Philosophy

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Dogbe, John Kofi. "Comparing cluster and slab model geometries from density functional theory calculations of si(100)-2x1 surfaces using low-energy electron diffraction." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3258835.

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Jones, Adrian Howard. "The acquisition, analysis and correlation of low energy electron diffraction and scanning tunnelling microscopy data from silicon surfaces." Thesis, University of York, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283430.

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梁艾芝 and Ai-chi Angela Leung. "Atomic structure studies of holmium on SI(111) surface by low energy electron diffraction Patterson inversion at multiple incident angles." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39558824.

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