Дисертації з теми "Inelastic Electron Tunnelling Spectroscopy"
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Sleigh, Anne Katherine. "Inelastic electron tunnelling spectroscopy of adsorbed molecules." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.346406.
Повний текст джерелаTaylor, M. E. "Substrate and electrode effects in inelastic electron tunnelling spectroscopy." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235265.
Повний текст джерелаKibble-Wilson, H. A. B. "Inelastic electron tunnelling spectroscopy of glasses and clusters." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377226.
Повний текст джерелаHamidizadeh, Yasaman. "Inelastic electron tunnelling spectroscopy using nanoscale tunnel junctions." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/26225.
Повний текст джерелаWerrett, C. R. "Inelastic Electron Tunnelling Spectroscopy (IETS) of saline coupling agents." Thesis, De Montfort University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377709.
Повний текст джерелаMallik, Robert Ronnan. "An investigation of polymeric adsorption on aluminium oxide by inelastic electron tunnelling spectroscopy." Thesis, De Montfort University, 1985. http://hdl.handle.net/2086/4251.
Повний текст джерелаLewis, David Malcolm. "A study of some molecular interactions on alumina surfaces by inelastic electron tunnelling spectroscopy." Thesis, City, University of London, 1985. http://openaccess.city.ac.uk/19019/.
Повний текст джерелаSpencer, Jonathan Edmund Downing. "A study of organotitanium coupling agents for adhesion promotion and of chemical reactions on alumina surfaces by inelastic electron tunnelling spectroscopy." Thesis, City University London, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254964.
Повний текст джерелаSpeakman, Alison. "Studies of tunnelling barriers." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239086.
Повний текст джерелаChandler, Simon John. "Electron tunnelling study of high-temperature superconductors." Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/270328.
Повний текст джерелаPeronio, Angelo. "A closer look at heterogeneous catalysis: reaction intermediates at the single-molecule level." Doctoral thesis, Università degli studi di Trieste, 2013. http://hdl.handle.net/10077/8577.
Повний текст джерелаThe present work pertains to the surface science approach to heterogeneous catalysis. In particular model systems for CO2 hydrogenation to methanol, and NO selective catalytic reduction, are investigated by means of a combined approach, where the molecular-level insight provided by a low-temperature scanning tunneling microscope is complemented by density functional theory (DFT) calculations of their electronic structure. To this end, the Inelastic Electron Tunneling Spectroscopy (STM-IETS) technique was introduced for the first time in our laboratory, a recent development which allows to measure the vibrational spectrum of individual molecules adsorbed on a surface. Regarding CO2, we provide single molecule imaging and characterization of CO2/Ni(110), chemisorbed with high charge transfer from the substrate, in an activated state that plays a crucial role in the hydrogenation process. We obtain a detailed characterization of the adsorption geometries and an estimate of the energies corresponding to the different adsorbed states. A consistent picture of CO2 chemisorption on Ni(110) is provided on the basis of the newly available information, yielding a deeper insight into the previously existing spectroscopic and theoretical data. In the Selective Catalytic Reduction (SCR) process, nitrogen oxide is selectively transformed to N2 by reductants such as ammonia. The specificity of this reaction was tentatively attributed to the formation of NH3-NO coadsorption complexes, as indicated by several surface science techniques. Here we characterize the NH3-NO complex at the atomic scale on the (111) surface of platinum, investigating the intermolecular interactions that tune the selectivity. The structures that arise upon coadsorption of NH3 and NO are analyzed in terms of adsorption sites, geometry, energetics and charge rearrangement. An ordered 2 × 2 adlayer forms, where the two molecules are arranged in a configuration that maximizes mutual interactions. In this structure, NH3 adsorbs on top and NO on fcc-hollow sites, leading to a cohesional stabilization of the extended layer by 0.29 eV/unit cell. The calculated vibrational energies of the individually-adsorbed species and of the coadsorption structure fit the experimental values found in literature within less than 6%. The characterizations and optimizations that had to be tackled in order to successfully perform STM-IETS measurement are eventually presented, focusing in particular on an original method which allows to increase the achieved resolution. Namely, the modulation broadening associated to phase-sensitive detection is reduced by employing a tailored modulation function, different from the commonly-used sinusoid. This method is not limited to STM-IETS, but can be easily applied whenever a lock-in amplifier is used to measure a second derivative.
XXV Ciclo
1984
Jackson, Michael David. "Scanning tunnelling microscope and electron spectroscopy studies of selected GaAs systems." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338676.
Повний текст джерелаPatil, Prashant (Prashant Tarachand). "Design and fabrication of electron energy filters for room temperature inelastic electron tunneling spectroscopy." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/91828.
Повний текст джерела22
Title as it appears in MIT degrees awarded booklet, September 18, 2013: Fabrication of quantum dots electron energy filters for inelastic electron tunneling spectroscopy Cataloged from PDF version of thesis.
Includes bibliographical references (pages 87-88).
Odor detection has wide range of applications in a variety of industries, including the agricultural, clinical diagnosis, pharmaceutical, cosmetics, food analysis, environmental and defense fields. Spectroscopic techniques such as FTIR and Raman are commonly used for electronic nose application. However, their application is limited by factors such as poor sensitivity, selectivity and non-portability. Inelastic electron tunneling spectroscopy (IETS) is an all electronic spectroscopy that has been extensively used to measure the vibrational modes of molecules and can be used for electronic nose application. It has several advantages such as ultra-high sensitivity and compact size. However, IETS requires cryogenic temperature to resolve molecular spectra, which limits its use in electronic nose application. A new theory of biological olfaction postulates that the odorant detectors inside a nose recognize an odorant's vibrations via inelastic electron tunneling (Turin, 1996). However, a biological system works at room temperature but conventional IET spectroscopy requires cryogenic temperatures. Thus posing the following question: Is it possible to resolve molecular vibrational spectra using inelastic electron tunneling spectroscopy at room temperature? IET spectroscopy involves the tunneling of electrons through an insulating barrier that is situated between two conducting metal electrodes. At room temperature, tunneling electrons possess thermal energy and occupy broad distribution of energy levels available in metals. This thermal distribution of electrons drastically reduces the resolution of IET spectroscopy. By reducing the thermal distribution of tunneling electrons at room temperature, we can increase the resolution of IET spectroscopy. The objective of this work is to develop electron energy filters to narrow down the thermal energy distribution of electrons at room temperature. I further evaluate the application of these electron energy filters to increase the resolution of IET spectroscopy at room temperature. Some recent advancements in nanomaterials, such as quantum dots with discrete electron energy levels are an excellent choice as electron energy filters. In metals, the continuous distribution of available energy states causes broad thermal distribution of electrons at room temperature. In contrast, quantum dots have discrete energy levels due to their small size. So even though electrons might possess thermal energy at room temperature, they can only occupy the discrete energy levels available in quantum dots. Hence, the thermal energy distribution of electrons can be narrowed down to the energy levels available in quantum dots. The electron energy filter designed in this work, consists of a 2-dimensional array of CdSe quantum dots of sizes around 2.5nm sandwiched between metal electrodes. Through electrical characterization of these devices, we can conclude that they can narrow down thermal distribution of electrons from 25meV down to around 10meV. However, to resolve the molecular vibrational energy level at room temperature, thermal energy distribution of electrons should be less than 6.6meV. Since array of quantum dots results in formation of energy minibands, this work suggests that single quantum dot should be used instead of array of dots to improve the performance of electron energy filters. Moreover, the study of electron transport through single quantum dots done in this work suggests that the size of the dot should be less than 2.5nm to be used in room temperature IET spectroscopy. Interestingly, this length scale is consistent with the size of donor and acceptor sites in odorant receptors potentially explaining how these receptors could be able to resolve molecular spectra at room temperatures.
by Prashant Patil.
S.M.
Ji, Tao. "Inelastic electron tunneling spectroscopy in molecular electronic devices from first-principles." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=96883.
Повний текст джерелаDans cette thèse, nous présentons des calculs ab initio de la spectroscopie à effet tunnel par électron inélastique (IETS)appliqués à des jonctions moléculaires. Dans le cadre d'une configuration électrode-molécule-électrode,la théorie de la fonctionnelle de la densité (DFT) est utilisée pour construire l'hamiltonien et les fonctions de Green hors-équilibres(NEGF) sont employées pour déterminer la densité électroniquedans des conditions hors-équilibre. Le cadrede la DFT-NEGF nous permet de calculer des quantités telles que la fonctionnelle d'énergie totale,les forces atomiques ainsi que la matrice de Hessian. L'approximationauto-consistante de Born (SCBA) est employée afin d'intégrer les vibrations moléculaires (phonons) dans le formalisme DFT-NEGF,une fois que le spectre des phonons et les vecteurs propres ont été calculés à partir de la matrice dynamique. Des méthodes d'optimisations géométriques sont aussi discutées en tant que part indispensable du formalisme,étant donné que la condition d'équilibre mécanique est essentielle afin de calculer correctement les propriétés des phonons du système.Afin de surmonter les difficultés numériques, particulièrement concernant la grande demandecomputationnelle requise pour le calcul du couplage électron-phonon, nous développons une approximation numérique pour la self-énergie associée aux phonons. De plus, en employant quelques hypothèses raisonables, nous dérivons une expression pour l'IETS calculée à partir de laseconde dérivée de la courbe I-V dans le butde réduire l'erreur associée à la différentiation numérique. L'utilisation de ces deux approximations diminuent grandement les exigences computationnelles et rendent les calculs possibles avec les capacités numériques actuelles.Comme application du formalisme DFT-NEGF-SCBA, nous calculons l'IETS de la jonction moléculaire or-octanedithiol(ODT)-or. La courbe I-V, la conductance et l'IETS obtenues par calculs ab initio sontdirectement comparées aux données expérimentales. Une compréhension microscopique du couplage électron-phonon pour une jonction moléculaire à effet tunnel est élaborée dans cet exemple. De plus, des comparaisons entre les jonctions ODT à hydrogène dissociatif et à hydrogène non-dissociatif ainsi queles différents comportements de transfert de charges sont présentés afin de montrer les effets de la formation du thiol dans la jonction moléculaire ODT.
Kula, Mathias. "Elastic and Inelastic Electron Tunneling in Molecular Devices." Licentiate thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3958.
Повний текст джерелаEvans, Alan Charles. "The study of condensed matter by deep inelastic neutron scattering." Thesis, University of Warwick, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387343.
Повний текст джерелаMellor, A. G. "Scanning tunnelling microscopy and electron spectroscopy studies of gold nanoparticles dispersed over rutile TiO2 (110)." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1566938/.
Повний текст джерелаBurema, Shiri. "Inelastic Electron Tunneling Spectroscopy with the Scanning Tunneling Microscope : a combined theory-experiment approach." Thesis, Lyon, École normale supérieure, 2013. http://www.theses.fr/2013ENSL0821.
Повний текст джерелаInelastic Electron Tunneling Spectroscopy (IETS) with the Scanning Tunneling Microscope (STM) is a novel vibrational spectroscopy technique that permits to characterize very subtle properties of molecules adsorbed on metallic surfaces. Its proposed symmetry-based propensity selection rules, however, fail to fully capture its exact mechanism and influencing factors; are not directly retraceable to an adsorbate property and are cumbersome. In this thesis, a theoretical approach was taken to improve them. An IETS simulation protocol has been developed, parameterized and benchmarked, and consequently used to calculate IETS spectra for a set of systematically related small molecules on copper surfaces. Extending IETS principles were deduced that refer to the tunneling state’s vacuum extension, the selective activating/quenching of certain types of modes due to the moieties’ electronic properties, and the applicability of a sum rule of IETS signals. Also, fingerprinting IETS-signals that enable discrimination between adsorbate orientations, the chemical nature of atoms and structural isomers were determined and a strategy using straightforward electronic density distribution properties of the isolated molecule to predict IETS activity without (large) computational cost was developed. This expertise was used to rationalize and interpret experimentally measured IETS spectra for adsorbed metalloporphyrins and metallophthalocyanines, being the first IETS studies of this large size. This experimental approach permitted to determine the current limitations of IETS-simulations. The associated identification shortcomings were resolved by conducting complementary STM-image simulations
Schuster, Roman. "Electron Energy-Loss Spectroscopy on Underdoped Cuprates and Transition-Metal Dichalcogenides." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-27333.
Повний текст джерелаThe present thesis describes electron energy-loss spectroscopy on underdoped cuprate superconductors and transition-metal dichalcogenides. After a brief introduction into the experimental method there are two experimental chapters. For the prototype cuprate system Ca2-xNaxCuO2Cl2 the behavior of the charge-transfer excitations is investigated as a function of doping. The observed substantial redistribution of spectral weight and the accompanying breakdown of their dispersion is discussed in terms of a coupling to the spin degrees of freedom within the copper-oxygen plane. For x=0.1 there is a pronounced symmetry breaking in the optical response function which is discussed in terms of different possible scenarios. The chapter on the dichalcogenides focuses on the properties of the charge-carrier plasmon which shows a negative dispersion for all representatives of this family exhibiting a charge-density wave instability. This behavior can be influenced by in-situ intercalation of additional charges, the result being a doping dependent plasmon dispersion. Several approaches to reconcile these findings are considered
Line, Mike. "A study of the adsorption of some polymers and Langmuir Blodgett film systems by inelastic electron tunneling spectroscopy (IETS)." Thesis, De Montfort University, 1994. http://hdl.handle.net/2086/2394.
Повний текст джерелаBattistoni, Andrea. "Broad band acoustic spectroscopy in disordered systems." Doctoral thesis, Università degli studi di Trieste, 2015. http://hdl.handle.net/10077/10942.
Повний текст джерелаThe present work of thesis is situated within the framework of the study of disordered systems as liquids and glasses. A liquid is a system characterized by long range translational invariance and by a short range ordered structure. In the liquid state, contrarily to the crystalline one, there is not structural periodicity and all we learnt from solid state physics (Block’s theorem, phonons, Brillouin’s zones, eigen-states of plane waves, etc.) must be fully revised. The macroscopic collective properties of condensed matter are the result of inter and intra-molecular interactions that are typified by characteristic time and space scales. A longstanding and powerful tool to investigate the collective nature of the microscopic processes inside the system is the acoustic spectroscopy. While in the case of crystalline phase we could take advantage of the periodical structure of the system, limiting our investigation to the so called first Brillouin zone, in order to characterize a disordered system we need to explore a widest as possible spectral range to access the all time and space scales in which the dynamical phenomena occur. This approach can be called Broad Band Acoustic Spectroscopy . My PhD activity was devoted to the development of new experimental methods and techniques allowing the exploration with continuity of dynamics evolving with timescales from tenth’s of ns’s to ps’s. I could test such Broad Band Acoustic Spectroscopy on a prototypical sample: acetonitrile, the liquid with highest dipole moment, known for its many different inter- and intra-molecular dynamics. Using several experimental and computational approaches I could characterize the main dynamical processes for such compound in its whole liquid phase. Thanks to the crossing of the all acquired information, it was possible to identify a mutual influence between different relaxations whose behaviour otherwise was not possible to correctly understand. After a brief introduction to contextualize the Broad Band Acoustic Spectroscopy in disordered systems, in Chapter 1 is presented an overview of the experimental techniques used to perform the measurements within this work. In this chapter, the first my original contribution to the extension of acoustic spectral range finds the place. Thanks to the design and realization of particular spatial filters it is now possible to perform Brillouin Light Scattering experiments with angle tunabil- ity without incurring in annoying spurious contributions issues. In the chapter are also recalled the main physical principles at the ground of every presented tech- nique, in particular stressing the complementarity of the energy and time resolved spectroscopies. Because all the information from the inner dynamics of the sample are mediated by the acoustic modes interaction, Chapter 2 is dedicated to the formalism of the density fluctuations, highlighting the differences between the hydrodynamic model, valid at macroscopic length-scales, and the memory functions approach, necessary to describe the mesoscopic region where the characteristic length-scales of the acoustic modes are comparable to the inter-particles distances. In Chapter 3 are shown the experimental results obtained thanks to the Broad Band Spectroscopy in the whole temperature range of the liquid phase of acetoni- trile. We could first measure some thermodynamical quantities by a non linear spectroscopy named Transient Grating, shedding light on the literature debate on them. Among the obtained results, we appreciated a temperature dependency of the heat capacity ratio which is usually considered a constant. Starting from these results and using the filtering approach introduced in Chapter 1, we could profitably study the vibrational relaxation of acetonitrile discovering some relevant discrepan- cies with previous studies. In this way we demonstrated the importance to avoid eventual spurious contributions and to have complementary information from dif- ferent spectral domains. Then there will be shown the results for the so called structural relaxation, obtained in the high energy domain by Inelastic X-ray Scat- tering. A really interesting correlation has been found with the result obtained by the ultrafast response of the Transient Grating method. Once again, to obtain such comparison was necessary to combine the information arising from many different spectral ranges, fact that highlights the utility and endorses the multi-techniques broad band acoustic spectroscopy method. The temperature dependence of the aforementioned relaxation processes sug- gested to evaluate if any coupling there exist between the two. This is exactly what we were able to appreciate in the deep-UV domain and we proposed a phenomeno- logical model to give a picture of the occurring interaction. To further investigate such dynamics coupling effect, could be extremely useful to explore the soft-UV spectral range but so far any technique was able to access such energy domain. In Chapter 4 we thus present our innovative solution to the problem: a novel table top Fabry-Perot interferometer conceived to operate with UV laser source and with only reflecting optics. The last chapters of the thesis describe my contribution to the forthcoming Free Electron Laser (FEL) based experiment to further increase the accessible spectral range to the acoustic spectroscopy: the TIMER project. In particular I will show the result obtained with the pilot experiment named “mini-TIMER” in which we could demonstrate the feasibility of a Transient Grating experiment in the Extreme Ultra Violet (EUV) domain. When TIMER will be operative it will be the first experimental setup able to probe the EUV mesoscopic region of crucial importance for the study of glasses and nano-structures. This result paves the way to a new class of intriguing experiments only matter of theoretical considerations so far: the so called four wave mixing experiments with elemental selectivity.
Il presente lavoro di tesi si colloca nell’ambito dello studio dei sistemi disordi- nati quali liquidi e vetri. Un liquido ´e un sistema caratterizzato da invarianza traslazionale a lungo raggio e da una struttura ordinata a corto raggio. Lo stato liquido, a differenza di quello cristallino, non gode di una periodicit`a strutturale e tutto ci`o che avevamo imparato dalla fisica dello stato solido (teorema di Block, fononi, zone di Brillouin, autostati di onde piane, etc.) deve essere completamente rivisto. Le propriet`a collettive della materia sono il risultato di interazioni a livello inter- e intra-molecolare identificate da caratteristiche scale temporali e spaziali. Uno strumento ormai affermato e utile per lo studio della natura collettiva dei processi microscopici attivi all’interno del sistema ´e la spettroscopia acustica. Mentre nel caso della fase cristallina si poteva sfruttare la natura periodica della struttura del sistema, limitando lo studio alla cosiddetta prima zona di Brillouin, per caratteriz- zare un sistema disordinato ´e necessario esplorare un intervallo spettrale il pi`u ampio possibile cosí da poter aver accesso alle scale spazio-temporali in cui le dinamiche avvengo. Questo tipo di approccio pu`o essere chiamato Spettroscopia Acustica ad Ampia Banda Spettrale . Il mio dottorato ´e stato dedicato allo sviluppo di nuovi metodi e tecniche speri- mentali per esplorare con continuit`a i processi dinamici la cui evoluzione avviene su scale di tempi tra le decine di ns e i ps. Tale Spettroscopia Acustica ad Ampia Banda Spettrale ´e stata testata su un campione prototipo di acetonitrile, il liquido con il pi´u alto momento di dipolo esistente, noto per le sue molteplici dinamiche di orgine inter- e intra-molecolare. Usando diversi approcci sperimentali e computazionali ´e stato possibile caratterizzare i principali processi di rilassamento per tale composto in tutta la sua fase liquida. Combinando poi tutte le informazioni acquisite, ´e stato possibile indentificare una mutua influenza tra i diversi processi di rilassamento il cui comportamento altrimenti sarebbe rimasto incompreso. Dopo una breve introduzione per contestualizzare la Spettroscopia Acustica ad Ampia Banda Spettrale nell’ambito dei sistemi disordinati, nel Capitolo 1 viene offerta una panoramica delle tecniche sperimentali usate per effettuare le misure nel corso di questo lavoro. Trova posto in questo capitolo la descrizione del mio primo originale contributo all’estensione dell’intervallo spettrale acustico. Grazie alla progettazione e realizzazione di particolari filtri spaziali ´e ora possibile effet- tuare esperimenti di diffusione di luce Brillouin con angolo di scattering variabile senza dover incorrere in fastidiosi problemi di contributi spuri. Nel capitolo vengono anche richiamati i principali elementi di fisica alla base di ogni tecnica, marcando in particolare la caratteristica di complementariet`a tra esperimenti risolti in tempo e in energia. Siccome tutte le informazioni a proposito delle dinamiche interne del campione sono mediate dall’interazione coi modi acustici, il Capitolo 2´e dedicato al formalismo delle fluttuazioni di densit`a, evidenziando le differenze tra il modello idrodinamico, valido per scale spaziali macroscopiche, e l’approccio delle funzioni memoria, nec- essario per descrivere la regione mesoscopica dove le dimensioni caratteristiche dei modi acustici diventano confrontabili con le distanze tra le particelle. Nel Capitolo 3 sono riportati i risultati sperimentali ottenuti mediante la Spet- troscopia Acustica ad Ampio Intervallo Spettrale nell’intero range di temperature in cui l’acetonitrile permane allo stato liquido. Per prima cosa, attraverso un tecnica fotonica di spettroscopia non lineare (Transient Grating) ´e stato possibile misurare alcune variabili termodinamiche, potendo fare chiarezza tra i vari contributi presenti in letteratura. Tra i risultati ottenuti, la dipendenza in temperatura del rapporto tra i calori specifici laddove usualmente viene considerata costante. Partendo da questi risultati e usando l’approccio di filtraggio introdotto nel Capitolo 1, ´e stato possibile studiare il rilassamento vibrazionale dell’acetonitrile scoprendo alcune ril- evanti discrepanze con i precedenti lavori riportati in letteratura. Abbiamo cosí dimostrato l’importanza di eliminare eventuali contributi spuri e di poter attingere a informazioni complementari da diversi domini spettrali. Verr`a inoltre mostrato il risultato dello studio del cosiddetto rilassamento strutturale effettuato nel range di alte energie grazie allo Scattering di raggi X. Una interessante correlazione si ´e po- tuta riscontrare tra i risultati di questo esperimento e quelli ottenuti con la tecnica Transient Grating nella sua risposta ultraveloce. Ancora una volta, per ottenere tale risultato ´e stato necessario combinare informazioni provenienti da molti inter- valli spettrali diversi, confermando la validit`a di un approccio multi-tecnica come quello della spettroscopia acustica a larga banda spettrale. L’andamento in tem- peratura dei suddetti processi di rilassamento suggerivano di valutare la presenza di un eventuale accoppiamento tra i due fenomeni. ´E esattamente ci`o che abbiamo osservato esplorando il dominio del profondo ultravioletto e per il quale abbiamo proposto un modello fenomenologico in grado di fornire una rappresentazione delle interazioni in gioco. Per poter approfondire tale fenomeno di accoppiamento sarebbe estremamente utile poter esplorare l’intervallo spettrale degli UV soffici, ma fino ad oggi nessuna tecnica era in grado accedere a tale range. Nel Capitolo 4 mostriamo la nostra innovativa soluzione al problema: un nuovo interferometro Farby-Perot “table-top”, concepito per lavorare con una sorgente UV laser e con sole ottiche riflettive. Gli ultimi capitoli della tesi descrivono il mio contributo al prossimo esperi- mento avente come sorgente di luce un laser ad elettroni liberi: il progetto TIMER, destinato ad aumentare ulteriormente il range spettrale sperimentalmente acces- sibile con la spettroscopia acustica. In particolare, mostrer`o i risultati ottenuti nell’esperimentopilotachiamato“mini-TIMER”graziealqualedimostratolapossibilit`a di effettuare un esperimento Transient Grating anche nel range spettrale dell’estremo UV (EUV). Quando TIMER sar`a operativo sar`a il primo setup sperimentale in grado di sondare la regione mesoscopica nell’EUV, zona di cruciale importanza per lo studio dei vetri e delle nanostrutture. Questo risultato apre inoltre la strada ad una nuova classe di interessanti esperimenti ad oggi oggetto solo di considerazioni teoriche: i cosiddetti esperimenti di “four wave mixing” combinati con la selettivit`a elementale che la radiazione EUV pu`o fornire.
XXVI Ciclo
1985
Zborowski, Charlotte. "Characterization of deeply buried interfaces by Hard X-ray Photoelectron Spectroscopy." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEC025/document.
Повний текст джерелаThis thesis aims at improving the inelastic background analysis method in order to apply it to technologically relevant samples. Actually, these improvements are utterly needed as they concern criteria of accuracy and time saving particularly for analysis of devices presenting deeply buried layers with different materials. For this purpose, the interest of the inelastic background analysis method is at its best when combined with hard X-ray photoelectron spectroscopy (HAXPES) because HAXPES allows to probe deeper in the sample than with conventional X-ray photoelectron spectroscopy (XPS). The present work deals with technologically relevant samples, mainly the high-electron mobility transistor (HEMT), at some crucial steps of their fabrication process as annealing. Actually, it is very important that these analyses shall be performed non-destructively in order to preserve the buried interfaces. These are often the location of complex phenomena that are critical for device performances and a better understanding is often a prerequisite for any improvement. In this thesis, the in-depth diffusion phenomena are studied with the inelastic background analysis technique (using the QUASES software) combined with HAXPES for depth up to 60 nm. The depth distribution results are determined with deviations from TEM measurements smaller than a typical value of 5%. The choice of the input parameters of the method is discussed over a large range of samples and simple rules are derived which make the actual analysis easier and faster to perform. Finally, it was shown that spectromicroscopy obtained with the HAXPEEM technique can provide spectra at each pixel usable for inelastic background analysis. This is a proof of principle that it can provide a 3D mapping of the elemental depth distribution with a nondestructive method
Denne afhandling har til formål at forbedre den uelastiske baggrundsanalysemetode til anvendelser i den til teknologiske industri. Faktisk er disse forbedringer absolut nødvendige, for at opnå nøjagtighed og tidsbesparelse, især for analyse af prøver med dybt begravede lag af forskellige materialer. Til det formål er interessen for den uelastiske baggrundsanalysemetode bedst i kombination med hård røntgenfotoelektron-spektroskopi (HAXPES), fordi HAXPES gør det muligt at probe dybere i prøven end med konventionel røntgenfotoelektron-spektroskopi (XPS). Dette arbejde beskæftiger sig med teknologisk relevante prøver, hovedsagelig høj-elektron mobilitetstransistor (HEMT), på nogle afgørende trin i deres fremstillingsproces som fx annealing. Faktisk er det meget vigtigt, at disse analyser udføres på en ikke-destruktiv måde for at bevare de begravede grænseflader. Det er ofte her de komplekse fysiske fænomener opstår, som er kritiske for fuktionaliteten, og en bedre forståelse af grænsefladerne er ofte en forudsætning for at kunne forbedre denne. I denne afhandling studeres de dybdegående diffusionsfænomener med den uelastiske baggrundsanalyse teknik (ved hjælp af QUASES software) kombineret med HAXPES for dybder op til 60 nm. Dybdestributionsresultaterne har afvigelser fra TEM-målinger mindre end en typisk værdi på 5%. Valget af input parametre for metoden er diskuteret på bagground af et stort udvalg af prøver samt omfattende simuleringer og enkle regler er udledt, hvilket gør den praktiske analyse nemmere og hurtigere at udføre. Endelig blev det vist, at spektromikroskopi opnået med HAXPEEM-teknikken kan tilvejebringe spektre ved hver enkelt pixel som kan anvendes til uelastisk baggrundsanalyse. Dette viser at i princippet kan en 3D-billeddannelse af den elementære dybdefordeling bestemmes ikke destruktivt
Karlsson, Patrik. "Surface Science Studies of Metal Oxides Formed by Chemical Vapour Deposition on Silicon." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7088.
Повний текст джерелаKersell, Heath Ryan. "Investigations on the Complex Rotations of Molecular Nanomachines." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1307126123.
Повний текст джерелаRahman, Shams ur. "Probing the effect of oxygen vacancies in strontium titanate single crystals." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:0b153fd2-3aa8-4fe5-b811-8ac42b4457fa.
Повний текст джерелаChelda, Samir. "Simulation du parcours des électrons élastiques dans les matériaux et structures. Application à la spectroscopie du pic élastique multi-modes MM-EPES." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2010. http://tel.archives-ouvertes.fr/tel-00629659.
Повний текст джерелаChen, Ting-Yun, and 陳廷芸. "Electromigration-Fabricated Molecular Junctions and the Instrumentation for Inelastic Electron Tunneling Spectroscopy." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/96182656034551926143.
Повний текст джерела國立臺灣大學
化學研究所
102
The study on charge transport through an MMM junction (metal-molecule-metal) is a fundamental method for investigation into molecular electronics. The second derivatives of the current-voltage curves yield inelastic electron tunneling spectroscopy (IETS). IETS originates from the excitation of the vibrational modes when electrons tunnel through a molecular junction. With vibrational modes consistent with Raman and infrared spectra, IETS provides spectroscopic evidence for the presence of molecules at the junctions. The devices are fabricated by photolithography and e-beam lithography, followed by electromigration technique. To obtain IETS of molecular junctions, the IETS circuit system is established with two lock-in amplifiers to acquire dI/dV and d2I/dV2 data directly from first and second harmonic signals. The signals obtained with lock-in amplifiers have better signal-to-noise ratios than those obtained numerically. The IETS circuit system is amended to improve the signal-to-noise ratio by integrating all required techniques in a customized program. The prominent peaks in the IETS of single-walled carbon nanotubes (SWNTs) obtained with the system can be assigned with the Raman spectra. However, not all of the peaks in the IETS of 1,4-butandithiol are consistent with reported IETS. It is presumed that the discrepancy comes from the noise and the geometry of the molecular junctions.
Chien-Chung, Huang. "Inelastic Electron Tunneling Spectroscopy Study on MBE-grown HfO2 Metal-Oxide-Semiconductor System." 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0016-1303200709285225.
Повний текст джерелаHuang, Chien-Chung, and 黃建中. "Inelastic Electron Tunneling Spectroscopy Study on MBE-grown HfO2 Metal-Oxide-Semiconductor System." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/22666632400445834342.
Повний текст джерела國立清華大學
物理學系
94
Inelastic electron tunneling spectroscopy (IETS) in silicon metal-oxide-semiconductor systems with SiO2, pure HfO2, pure Y2O3, stacked Y2O3/HfO2, and stacked HfO2/Y2O3 as gate dielectrics have all been studied in this work. Information of electrode phonons, dielectric phonons, chemical bonding, and trap-related states in MOS structures has been able to be revealed by IETS. The bias polarity dependence of IETS has enabled the distinguishability to analyze microstructures either near the metal gate interface or near the silicon substrate interface. IETS results from HfO2 MOS tunnel junctions are consistent with published experimental and theoretical works relevant to Raman- and Infrared- active HfO2 phonon modes in monoclinic and tetragonal phases. IETS results of stacked Y2O3/HfO2 gate dielectrics, compared to pure HfO2, show less formation of hafnium silicate and less HfO2 and Y2O3 phonon peaks that can be detected with energies close to silicon phonons. Both phenomena observed are probably associated with less charge trapping and less ionic polarization of HfO2 and Y2O3 or intrinsically smaller ionic polarization of Y2O3 which may contribute to the improvement of channel carrier mobility due to suppressed coulomb scattering and reduced remote phonon scattering, respectively.
Lai, Ying-Yu, and 賴盈妤. "Fabrication of Electrode-SWNT-Electrode Platform for Inelastic Electron Tunneling Spectroscopy by Focused Ion/Electron Beam-induced Deposition." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/6u55sp.
Повний текст джерела國立臺灣大學
化學研究所
103
Forming stable MMM (Metal-Molecule-Metal) junctions is a fundamental method for studying electric properties of a tailored single molecule. Low successful rates (< 10%) of fabricating three-electrode single-molecular transistor (SMT) by electromigration provokes us to propose a new molecular electronic platform: Synthesize “m-SWNT−Molecule−m-SWNT” (metallic single-walled carbon nanotube) configurations first, and then deposit metal film electrodes by FIBD or FEBID (focused ion/electron beam-induced deposition). So far, Pt−m-SWNT−Pt devices have been fabricated and measured. Unexpected results are attributed to deposition mechanism of FIBD or FEBID. FIBD Part: Electrodes deposited by FIBD are always surrounded by “halo” structure. While the distance of two electrodes is less than 500 nm, leakage current arising from overlap of nearby platinum halo of two electrodes would be measured. Temperature-variable I−V result shows that conductance of Pt−m-SWNT−Pt device decreases with temperature, which is not consistent with m-SWNT characteristic. Besides, IETS (inelastic electron tunneling spectroscopy) peaks corresponding to vibrational modes of m-SWNT such as radial breathing mode (100~350 cm‒1) and carbon-carbon bond stretching of graphite-like material, G band (~1600 cm‒1) are nearly undetectable. FEBID Part: Platinum halo less extend in FEBID. IETS signals of m-SWNT are detected. However, the amount of “remaining carbon residue” in the platinum electrodes is so significant that it result in lower conductance of device (~0.025 G0), which is much less than quantum conductance of m-SWNT (2 G0). It is also presumed that discrepancy of temperature-variable I−V result also comes from less quantity of “platinum”. In summary, owing to deposition mechanism of FIBD and FEBID, some features of m-SWNT are not observed in Pt−m-SWNT−Pt devices. Adjusting fabrication parameters or introducing other lithography may improve device performance.
Weismann, Alexander. "Scanning Tunnelling Spectroscopy of Subsurface Magnetic Atoms in Copper." Doctoral thesis, 2008. http://hdl.handle.net/11858/00-1735-0000-0006-B485-B.
Повний текст джерелаYou, Syuan-Long, та 游璇龍. "Inelastic Electron Tunneling Spectroscopy Study of Metal-Oxide-Semiconductor Device with High-κ Gate Dielectrics". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/64527609899000847423.
Повний текст джерела國立清華大學
物理學系
95
Inelastic electron tunneling spectroscopy (IETS) has been extensively applied to characterize the microstructure, trap-related states, and interfacial properties in silicon MOS system due to its unique ability to detect the interaction of tunneling electrons with energy-loss modes in the tunnel barrier. In this work, we reported the study of IETS in silicon metal-oxide-semiconductor (MOS) device with HfO2, Y2O3, YDH (yttrium-doped HfO2), and stacked HfO2/Y2O3 as gate dielectric. A systematical comparison between high-κ dielectrics thin films deposited by MBE and ALD in terms of microstructure and interfacial properties was presented in this study. The trap-related state induced by electrical stress in high-κ dielectrics thin film was also investigated by IETS spectra. The vibrational modes of HfO2 and Y2O3 from IETS measurement were identified by referring to the results from Raman, Infrared spectroscopy, and IETS by other authors. IETS technique was also applied to study the structural phase transformation in yttrium-doped HfO2 thin film. In addition to vibrational modes and chemical bonding, the location and energy level of traps contained in stacked HfO2/Y2O3 structure can be estimated by analyzing the trap-related feature in IETS spectra through a simple modeling.
Weismann, Alexander [Verfasser]. "Scanning tunnelling spectroscopy of subsurface magnetic atoms in copper : electron focusing and Kondo effect / vorgelegt von Alexander Weismann." 2008. http://d-nb.info/995994323/34.
Повний текст джерелаSchuster, Roman. "Electron Energy-Loss Spectroscopy on Underdoped Cuprates and Transition-Metal Dichalcogenides." Doctoral thesis, 2009. https://tud.qucosa.de/id/qucosa%3A25247.
Повний текст джерелаThe present thesis describes electron energy-loss spectroscopy on underdoped cuprate superconductors and transition-metal dichalcogenides. After a brief introduction into the experimental method there are two experimental chapters. For the prototype cuprate system Ca2-xNaxCuO2Cl2 the behavior of the charge-transfer excitations is investigated as a function of doping. The observed substantial redistribution of spectral weight and the accompanying breakdown of their dispersion is discussed in terms of a coupling to the spin degrees of freedom within the copper-oxygen plane. For x=0.1 there is a pronounced symmetry breaking in the optical response function which is discussed in terms of different possible scenarios. The chapter on the dichalcogenides focuses on the properties of the charge-carrier plasmon which shows a negative dispersion for all representatives of this family exhibiting a charge-density wave instability. This behavior can be influenced by in-situ intercalation of additional charges, the result being a doping dependent plasmon dispersion. Several approaches to reconcile these findings are considered.
Lu, Shao-Yu, та 呂紹宇. "Ab-initio molecular dynamic simulation studies: 1. Temperature induced carbon-halogen dissociated reaction and Cα-Cα self-coupling reactions 2. STM-tip induced CO(ads) desorption reaction and their inelastic electron tunneling spectroscopy". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/ju5e4k.
Повний текст джерела淡江大學
化學學系博士班
103
Density functional theory (DFT)-based molecular dynamic simulation in combination with time-resolved simulated reflected infrared adsorption spectroscopy is performed to study 1) the dynamic behavior of catalytic reaction for carbon-halogen dissociation and carbon-carbon self-coupling reaction on metal surface. 2) In addition, we performed our new methodology to generate the inelastic electron tunneling spectroscopy by collecting the dynamic trajectories of local density of state (LDOS) to investigate the STM-tip induced CO desorption reaction. In the part I of my thesis, firstly, we successfully investigate the adsorption behaviours of carbon-halogen rupture reaction for propargyl bromide (HC≡C(β)-C(α)H2Br(ads)) and propynyl iodide (CH3-C(β)≡C(α)-I(ads)) on Ag(111) surface by using DFT-based MD simulation. We found that the carbon-Ag interaction can induce the weakening of carbon-halogen bond due to the delocalization effect between the adsorbed molecule and Ag surface at transition state. In addition, the time-resolved spectra constructed by short-time Fourier transform (STFT) illustrate that the evolution of all the vibrational modes along the carbon-halogen dissociation reaction and have a good agreement with experimental RAIRS results. Secondly, we investigated the thermally induced diffusion processes of different hybridization state of Cα that is, methyl acetylide (CH3-C(β)≡C(α)(ads) : sp hybridization of Cα atom) and ethyl (H3C(β)-C(α)H2(ads) : sp3 hybridization of Cα atom), respectively. Our results indicate that the CH3-C(β)≡C(α)(ads) is very stable due to the strong π-back donation effect as methyl acetylide adsorbed on Ag(111) surface. Therefore the methyl acetylide will have higher diffusion temperature than that of ethyl on the same surface leading to the higher reaction temperature for the Cα-Cα self-coupling reaction. In the part II of my thesis, the DFT-based MD simulation with a Fourier transform of the derivative of local density of states autocorrelation function is introduced to generate the inelastic electron tunnelling spectra for evaluating he effect of STM-tip on adsorption dynamics for CO(ads) on the Ag(110) surface. Based on dynamic results, the STM-tip can induce the desorption process of CO on Ag(110) to produce a functionalized STM-tip (CO-terminated Ag5 cluster tip). By using the STFT, the anharmonic coupling between the frustrated rotation and CO stretching mode can be investigated. Finally, the CO-terminated Ag5 cluster tip can be further used to scan the CoPz (Cobalt porphyrazin) on Ag(110) to generate the local IETS spectrum. Our new methodology successfully observe the frustrated translation of CO vibration senses the spatially varying potential energy landscape of the molecule and its surroundings and have a good agreement with experimental IETS results.
Gawraczyński, Jakub. "Optical spectroscopy of selected divalent silver compounds." Doctoral thesis, 2019. https://depotuw.ceon.pl/handle/item/3382.
Повний текст джерелаThis doctoral dissertation describes research on silver compounds carried out with a range of spectroscopic methods. The main focus of the thesis was on divalent silver compounds: AgF2, AgSO4, AgSO4∙H2O, (AgF)BF4, CsAgF3, RbAgF3, and high-temperature form of KAgF3. In addition, other silver compounds were investigated, particularly AgF and silver(I, III) oxide AgO. All compounds were studied by FT-FIR spectroscopy, some were also investigated with Raman spectroscopy (at ambient or high pressure), MIR, NIR, as well as UV and visible absorption spectroscopy and by inelastic neutron scattering. The main scope of the work was to get insight into vibrational structure of the studied compounds as well as understand their pressure-induced phase transitions. The second goal was to determine magnetic superexchange constants for 2D AgF2 from Raman scattering spectra, and for 1D AgFBF4 from NIR-absorption spectra. The auxiliary task, dictated by the course of the experimental work, was to understand photochemical decomposition of AgF2 and AgSO4. The spectroscopic measurements of AgIISO4 prepared using the new electrosynthesis method in concentrated H2SO4 showed its similarity with the product of chemical synthesis developed earlier, albeit substantial differences in reactivity to water vapor were also found. In addition, the laser-induced decomposition of AgIISO4 was observed and it was shown that the decomposition product is dependent on the wavelength of the laser used. A similar photosensitivity was observed in AgIISO4∙H2O. The hydrate was also studied spectroscopically from far-infrared to UV, which allowed determination of the orbital splitting parameters as well as has provided the supplementary evidence for the presence of water molecules in its crystal structure. Research on AgF at high pressure showed the presence of several Raman bands in contrast with predictions of group theory (no Raman-active bands), some of them probably originating from color centers or overtone of the IR-active fundamental. Research on AgF2 proved its high photosensitivity to laser light. Laser-induced photodecomposition product has been studied in the range from atmospheric pressure up to 47 GPa. The decomposition product seems to contain Ag(II)F42– anion, notably Ag(I)2Ag(II)F4, which is the first mixed-valence Ag(I)/Ag(II) fluoride known. Pressure dependence of the characteristic Raman band for this phase was measured up to 47 GPa. In addition, using Raman scattering spectroscopy and inelastic neutron scattering, I have successfully identified and measured for the first time the bimagnon transitions in 2D antiferromagnet, AgF2, and determined the value of the intra-sheet magnetic superexchange constant, J. The large value of J=70 meV sets this compound second only to lamellar oxocuprates(II). (AgF)BF4 has been characterized by Raman scattering, inelastic neutron scattering, IR absorption and reflection spectroscopy. The characteristic band appearing in the NIR absorption spectra enabled estimation of the intra-chain magnetic superexchange constant for this compound to be about 270 meV. This value surpasses the largest known superexchange constant ever measured (240 meV for Sr2CuO3). Research on AgO conducted under a high pressure showed no pressure-induced decomposition or comproportionation of this compound to no less than 74 GPa. Due to the good agreement of the experimental Raman band positions with those derived from the theoretical calculations made on the AgO high-pressure models, it was possible to demonstrate the existence of two structural phase transitions in the pressure range from 0 to 74 GPa. The research carried out on three alkali metal fluoroargentates: CsAgF3, RbAgF3, and high-temperature form of KAgF3 has shown that despite clear structural differences between them, the Fourier transmission spectra in the far infrared range of all compounds show substantial similarity.