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This research will investigate the problem on the propagation of electromagnetic wave through a specific nanomaterial. The nanomaterial analyzed is a material consisting of a field of Pt nanorods. This field of Pt nanorods are deposited on a substrate which consists of a RuO2 nano structure. When the nanorod is exposed to an electron beam emitted by a TEM (Transmission electron microscopy). A wave disturbance has been observed. A video taken within the chamber shows a wave with a speed in the scale of um/s (Á?10Á?^(-6) m/s), which is 14 orders of magnitude lower than speed of light in free space (approximate 3ÁÁ?10Á?^8 m/s ). A physical and mathematical model is developed to explain this phenomenon. Due to the process of fabrication, the geometry of the decorated Pt nanorod field is assumed to be approximately periodic. The nanomaterials possess properties similar to a photonic crystal. Pt, as a noble metal, shows dispersive behaviours that is different from those ones of a perfect or good conductors. A FDTD algorithm is implemented to calculate the band diagram of the nanomaterials. To explore the dispersive properties of the Pt nanorod field, the FDTD algorithm is corrected with a Drude Model. The analysis of the corrected band diagram illustrates that the group velocity of the wave packet propagating through the nanomaterial can be positive, negative or zero. The possible zero-group velocity is therefore used to explain the extremely low velocity of wave (wave envelope) detected in the TEM.

M-plane (101 ¡Â0) ZnO thin films were grown on m-plane sapphire (101 ¡Â0) substrates by RF magnetron sputtering. We varied the RF power, working pressure, and O2/Ar ratio to obtain the best growth conditions. Structural properties were investigated by X-ray diffraction(XRD). XRD measurements showed that the crystal orientation of ZnO films was non-polar m-plane (101 ¡Â0). In addition, photoluminescence (PL) spectrum showed the bandgap energy of ZnO films was about 3.24 eV. PL spectrum showed zinc vacancy signal for films grown in oxygen rich condition. Carrier concentration was measured by hall measurement as well as FTIR spectrometry. The results showed the carrier concentration calculated by optical measurements was higher than hall measurements. One possibility for this could be the band tail at the bottom of conduction band. This band tail can make the effective mass larger and thus influencing the optical carrier concentration.

This thesis is on the topic of investigation of the characteristics of DC Glow Discharge plasmas. Emphasis is given on characterizing the plasma electron density. The methods of generating and detecting THz pulses are described. THz transmission spectroscopy and plasma emission spectroscopy is examined. Transmission spectrum is taken for Air, gaseous Nitrogen and Argon plasmas. Moreover, emission spectrum of Air, N2 and Ar plasma analysis were done respectively. It was found that the transmission of terahertz pulses through nitrogen plasma was considerably affected compared to that of the argon plasma. Initially Drude model theory of electron conduction is employed to analyze the plasma density.

Creation of ultrafast semiconductor components is inconceivable without understanding various processes of picoscond duration in semiconductors. These processes, as electron energy relaxation time or nonequiriblium carrier capture are very important for semiconductor photonics and terahertz range devices. Since now, the most popular tool of measuring ultrafast processes in semiconductors was picosecond or femtosecond laser pulses. In spite of excellent time resolution, optical pump – probe methods have a significant imperfection. Interpretation of the results can be very complicate. Also, the measured result can be affected by few variable parameters or interaction of various physical phenomenon. Therefore determinate results can be hardly related with electron time dependent characteristic. The aim of this dissertation was to measure electron energy relaxation times and electron life times by using terahertz pulses in narrow – gap semiconductors used for photoconductive terahertz emitters or detectors. In this dissertation, electron characteristic times witch describe various processes in semiconductor, were studied. These measurements were performed by optical pump – terahertz probe technique and time domain terahertz spectroscopy. The emission of terahertz pulses from the semiconductor surface, illuminated by femtosecond laser pulses, was investigated. / Ultrasparčių puslaidininkinių komponentų kūrimas reikalauja gilesnio supratimo apie tai, kaip puslaidininkiuose vyksta fizikiniai procesai, trunkantys kelias pikosekundes ar net mažiau nei vieną pikosekundę. Tokie reiškiniai, kaip elektronų impulso ir energijos relaksacija bei nepusiausvyrųjų krūvininkų pagavimas yra labai svarbūs puslaidininkinių fotonikos ir terahercinio diapazono prietaisų veikimui. Iki pastarojo meto pagrindinis ultrasparčiųjų procesų puslaidininkiuose tyrimo įrankis buvo optiniai metodai, kuriuose elektronų dinamikai stebėti buvo pasitelkiami pikosekundinių ar femtosekundinių lazerių impulsai. Nepaisant išskirtinai didelės šių metodų laikinės skyros, optinio kaupinimo-zondavimo matavimų rezultatus yra palyginti sudėtinga interpretuoti. Šie rezultatai dažniausiai yra įtakojami kelių sistemos parametrų kitimo ir įvairių fizikinių reiškinių tarpusavio sąveikos, todėl sunkiai susiejamas su kuria nors elektronų laikine charakteristika. Disertacijos darbo tikslas – naudojant terahercinės spinduliuotės impulsus išmatuoti elektronų impulso ir energijos relaksacijos trukmes keliuose siauratarpiuose puslaidininkiuose bei jų gyvavimo trukmes medžiagose, skirtose fotolaidžių terahercinės spinduliuotės emiterių ir detektorių gamybai. Šioje disertacijoje yra pateikiami įvairių charakteringų elektroninius procesus puslaidininkiuose apibūdinančių trukmių matavimų naudojant terahercinės spinduliuotės impulsus rezultatai. Tokie tyrimai atlikti ir optinio žadinimo –... [toliau žr. visą tekstą]

Ultrasparčių puslaidininkinių komponentų kūrimas reikalauja gilesnio supratimo apie tai, kaip puslaidininkiuose vyksta fizikiniai procesai, trunkantys kelias pikosekundes ar net mažiau nei vieną pikosekundę. Tokie reiškiniai, kaip elektronų impulso ir energijos relaksacija bei nepusiausvyrųjų krūvininkų pagavimas yra labai svarbūs puslaidininkinių fotonikos ir terahercinio diapazono prietaisų veikimui. Iki pastarojo meto pagrindinis ultrasparčiųjų procesų puslaidininkiuose tyrimo įrankis buvo optiniai metodai, kuriuose elektronų dinamikai stebėti buvo pasitelkiami pikosekundinių ar femtosekundinių lazerių impulsai. Nepaisant išskirtinai didelės šių metodų laikinės skyros, optinio kaupinimo-zondavimo matavimų rezultatus yra palyginti sudėtinga interpretuoti. Šie rezultatai dažniausiai yra įtakojami kelių sistemos parametrų kitimo ir įvairių fizikinių reiškinių tarpusavio sąveikos, todėl sunkiai susiejamas su kuria nors elektronų laikine charakteristika. Disertacijos darbo tikslas – naudojant terahercinės spinduliuotės impulsus išmatuoti elektronų impulso ir energijos relaksacijos trukmes keliuose siauratarpiuose puslaidininkiuose bei jų gyvavimo trukmes medžiagose, skirtose fotolaidžių terahercinės spinduliuotės emiterių ir detektorių gamybai. Šioje disertacijoje yra pateikiami įvairių charakteringų elektroninius procesus puslaidininkiuose apibūdinančių trukmių matavimų naudojant terahercinės spinduliuotės impulsus rezultatai. Tokie tyrimai atlikti ir optinio žadinimo –... [toliau žr. visą tekstą] / Creation of ultrafast semiconductor components is inconceivable without understanding various processes of picoscond duration in semiconductors. These processes, as electron energy relaxation time or nonequiriblium carrier capture are very important for semiconductor photonics and terahertz range devices. Since now, the most popular tool of measuring ultrafast processes in semiconductors was picosecond or femtosecond laser pulses. In spite of excellent time resolution, optical pump – probe methods have a significant imperfection. Interpretation of the results can be very complicate. Also, the measured result can be affected by few variable parameters or interaction of various physical phenomenon. Therefore determinate results can be hardly related with electron time dependent characteristic. The aim of this dissertation was to measure electron energy relaxation times and electron life times by using terahertz pulses in narrow – gap semiconductors used for photoconductive terahertz emitters or detectors. In this dissertation, electron characteristic times witch describe various processes in semiconductor, were studied. These measurements were performed by optical pump – terahertz probe technique and time domain terahertz spectroscopy. The emission of terahertz pulses from the semiconductor surface, illuminated by femtosecond laser pulses, was investigated.

Disertační práce se zabývá modelováním dispersních materiálů metodou konečných prvků v časové oblasti. V práci jsem navrhl matematický model zahrnující dispersní modely a aplikoval jsem na něj metodu konečných prvků. Pozornost jsem věnoval třem nejvíce používaným dispersním modelům. Jedná se o Debyeho model, Lorentzův model a Drudův model. Dále jsem se zabýval technikami implementace těchto dispersních modelů. Techniky jsem zabudoval do metody konečných prvků. Navíc jsem vyvinul novou metodu založenou na technice digitální filtrace. Funkčnost vyvinutých metod a technik jsem ověřil na řadě testovacích příkladů. Diskutoval jsem dosažené výsledky a navrhuji jejich možná vylepšení.

Les recherches présentées dans ce mémoire ont été rendues possible grâce à la contribution financière du CRSNG, par à leur Programme de subventions à la découverte (SD) et leur Programme de bourses d’études supérieures du Canada au niveau de la maîtrise (BESC M); du FRQNT, par leur Programme de bourse de maîtrise (B1); et du CLS, par leur Graduate and Post-Doctoral Student Travel Support Program. / Le graphène est un nano-matériau très prometteur grâce à ses excellentes propriétés mécaniques, optiques et électriques. Toutefois, la plupart de ses applications les plus novatrices requièrent de l'altérer, mais la compréhension du graphène altéré est encore limitée. Certaines applications envisagées sont en optique infrarouge. Or, notre compréhension actuelle du graphène ne permet pas d’expliquer l’apparition des pics infrarouges qui sont observés dans les bicouches et dans les monocouches fonctionnalisées. Le comportement du graphène fonctionnalisé est particulièrement contre-intuitif, puisque l’ajout de greffons le rend plus transparent, et non pas plus opaque! Un modèle proposé par Bruno Rousseau, un étudiant post-doctorant du professeur Michel Côté à l'Université de Montréal, suggère une explication à ce phénomène: bien que les phonons du graphène ne puissent pas coupler directement avec la lumière, ils coupleraient indirectement avec celle-ci grâce à des collisions sur les électrons, qui eux, peuvent coupler avec les photons. Ce couplage indirect peut produire des interférences parfois constructives, parfois destructives, de telle sorte que ce mécanisme peut autant produire des pics d’absorbance que de transparence. Dans le cadre de ce mémoire, nous avons entrepris de vérifier expérimentalement la validité de ce modèle, et nous concluons qu’il semble prédire adéquatement le comportement de l’activité infrarouge des bicouches de graphène et des monocouches fonctionnalisées. Nous avons aussi étudié les méthodes par lesquelles nous synthétisions ces différents types de graphène afin de les optimiser. Enfin, nous avons déterminé des techniques, basées sur la spectroscopie Raman, permettant de bien caractériser l’intensité de l’altération causée par ces méthodes. / Graphene is a promising nanomaterials thanks to its excellent mechanical, optical and electrical properties. However, its most innovative applications require that it be altered, but the understanding altered graphene is still limited. Some applications are considered in infrared optics. However, our current understanding of graphene does not explain the appearance of the infrared peaks that are observed in bilayers and grafted monolayers. The behaviour of grafted graphene is especially baffling, since the addition of grafts makes it more transparent, not less! A model proposed by Bruno Rousseau, a postdoctoral student of Professor Michel Côté at Université de Montréal, suggests an explanation for this phenomenon: although the phonons of graphene cannot couple directly with light, they could couple indirectly through collisions with the electrons, which can couple with photons. This indirect coupling may produce constructive and destructive interference, depending on the conditions, so this mechanism can produce absorbance peaks as much as transparency peaks. In this master’s thesis, we have undertaken to experimentally verify the validity of this model, and we conclude that it seems to adequately predict the behaviour of the infrared activity of graphene bilayers and grafted monolayers. We also studied the methods by which we synthesized these different types of graphene to optimize them. Finally, we determined techniques based on Raman spectroscopy to characterize the intensity of the alteration induced by these methods.

This thesis describes investigations into the properties of -phase BEDT-TTF charge transfer salts. Charge transfer salts are mainly studied as they are very useful test beds for fundamental physics due to the tuneability of their proper- ties and ground states. The effects of temperature and pressure on such systems have been studied, as these allow access to a wide range of different states and properties. Transport properties of these systems have been studied to obtain information about the Fermi surface and effective mass, and the effect of deuter- ation and also change of pressure media will be discussed. The interaction of infrared radiation with these systems has also been investigated and simultaneous pressure and temperature measurements will be presented, something not greatly studied due to the large technical challenges. The techniques and approaches for overcoming these are also discussed. Chapter 1 provides an introduction to the organic materials themselves with particular emphasis on the actual compounds studied. Chapter 2 provides the necessary theoretical background for studying organic charge transfer salts using magnetic quantum oscillations and their infrared re- ectivity. Chapter 3 covers the experimental techniques and also discusses some of the challenges encountered and their solutions to aid others working in this area. Chapter 4 describes an investigation into the transport properties of - (ET)2Cu(SCN)2 by studying Shubnikov-de Haas oscillations using both deuter- ated and normal samples and using two different pressure media, and comparing it to work done using a third. Chapter 5 presents an investigation into the pressure dependence of selected phonon modes in -(ET)2Cu(SCN)2 using infrared radiation on a deuterated sam- ple. Chapter 6 presents what is believed to be the first pressure and temperature dependent infrared study of an organic molecular material. In this case the or- ganic molecular material is d8--(ET)2Cu[N(CN)2]Br, but the techniques should be readily transferable to other materials.

In dieser Arbeit werden die nichtlokalen sowie nichtlinearen Eigenschaften plasmonischer Nanopartikel behandelt, wie sie im hydrodynamischen Modell enthalten sind. Das hydrodynamische Materialmodell stellt eine Erweiterung des Drude Modells dar, in der Korrekturen in der Beschreibung des Elektronenplasmas berücksichtigt werden. Einer ausführlichen Einführung des Materialmodells folgt eine analytische Diskussion der Auswirkungen der Nichtlokalität am Beispiel eines einzelnen Zylinders. Hierbei werden die durch die Nichtlokalität herbeigeführten Frequenzverschiebungen in den Streu- und Absorptionsspektren quantifiziert und asymptotisch behandelt. Des Weiteren wird mit Hilfe einer konformen Abbildung das Problem eines zylindrischen Dimers in der Elektrostatischen Näherung gelöst und die Moden der Struktur bestimmt. Diese Untersuchungen dienen als maßgebliche Grundlage für weiterführende numerische Studien die mit der diskontinuierlichen Galerkin Zeitraummethode durchgeführt werden. Die durch die analytischen Betrachtungen gewonnene Kenntnis der Moden ermöglicht es, im Zusammenhang mit gruppentheoretischen Betrachtungen und numerischen Untersuchungen, rigorose Auswahlregeln für die Anregung der Moden durch lineare und nichtlineare Prozesse aufzustellen. In weiterführenden numerischen Simulationen werden außerdem Strukturen niedrigerer Symmetrie, auf die sich die Auswahlregeln übertragen lassen, untersucht. Zudem werden numerische Studien präsentiert in denen der Einfluss der Nichtlokalität auf Feldüberhöhungen in Dimeren und doppel-resonantes Verhalten (es liegt sowohl bei der Frequenz des eingestrahlten Lichtes als auch bei der zweiten harmonischen eine Resonanz vor) untersucht werden. / This thesis deals with the nonlocal and nonlinear properties of plasmonic nanoparticles, as described by the hydrodynamic model. The hydrodynamic material model represents an extension of the Drude model that contains corrections to the descriptions of the electron plasma. After a thorough derivation of the material model, analytical discussions of nonlocality are presented for the example of a single cylinder. The frequency shifts in the scattering and absorption spectra are quantified and treated asymptotically. Furthermore, by applying a conformal map, the problem of a cylindrical dimer is solved in the electrostatic limit and the modes of the structure are determined. These investigations lay the foundations for numerical investigations which are performed employing the discontinuous Galerkin time domain method. The analytical knowledge of the modes, in conjunction with group theoretical considerations and numerical analysis, enables the formulation of rigorous selection rules for the excitation of modes by linear and nonlinear processes. In further numerical studies, the influence of nonlocality on the field enhancement in dimer structures and double-resonant behavior (a resonance is found at the frequency of the incoming light and at the second harmonic) are investigated.