Dissertations / Theses on the topic 'Non-polar'
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Newsham, David K. Sen Ayusman. "Palladium catalyzed copolymerizations of polar and non-polar monomers." [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-4528/index.html.
Full textHanan, Faridah Hanim Ab. "Plasticizer transportation studies in polar and non-polar rubbers." Thesis, London Metropolitan University, 2001. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341733.
Full textSILVA, ELIZANDRA MARTINS. "NANOSCALE MECHANICAL DEFORMATION MECHANISMS OF POLAR AND NON-POLAR ZNO." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2014. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=24779@1.
Full textCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
Neste trabalho foi estudado o mecanismo de deformação de faces polares e não polares do óxido de zinco (ZnO), através da introdução de defeitos mecânicos por nanoindentação. A estrutura cristalina estável do ZnO é do tipo wurtzita, de forte caráter anisotrópico já observado em relação a propriedades como piezoeletricidade e polarização espontânea. O mecanismo de deformação mecânica desses sistemas ainda não está bem esclarecido e são de vital importância na otimização de dispositivos optoeletrônicos. A extensão dos defeitos para cada orientação do cristal foi analisada via microscopia eletrônica de transmissão e correlacionada com o movimento de planos basais {0001} de forma divergente, em faces não polares (1100) e (1120), e ao movimento de planos piramidais {1011} de forma convergente para faces polares (0001) e (0001). A extensão da deformação induzida abaixo da superfície foi avaliada, onde foi possível identificar a formação de discordâncias do tipo parafuso que se propagam através do sistema de escorregamento (1120)(0001), se propagando de forma altamente localizada abaixo da superfície. O início da deformação plástica em monocristais é marcado por eventos plásticos súbitos (pop-ins). Estes eventos foram identificados e analisados em função da força e da extensão da deformação gerada. A topografia e forma das impressões residuais foi analisada usando microscopia de força atômica. Os defeitos observados no plano superficial tenderam a se propagar em direções preferenciais num processo induzido pela formação de zonas de tensão em torno da indentação. A formação de zonas de tensão trativa em uma dada direção aumenta a mobilidade das discordâncias, enquanto zonas de tensão compressiva agem contribuindo para o travamento. Estas zonas foram identificadas e a magnitude desta tensão foi estimada via catodoluminescência. Observamos também que a face polar (0001) apresentou um comportamento reativo, onde defeitos localizados abaixo da superfície foram revelados através do processo de limpeza.
In this work, deformation mechanisms of polar and non-polar zinc oxide (ZnO) were studied by nanoindentation tests. The stable crystal structure of ZnO is the wurtzite with a strong anisotropic character observed in relation to the piezoelectricity and spontaneous polarization properties, for example. The mechanical deformation mechanisms of these sorts of materials are not yet fully understood, being of vital importance for optoelectronic devices optimization.For each ZnO crystallographic orientation, the induced defects damages were analyzed by transmission electron microscopy (TEM) and correlated with the slip of basal planes {0001} in the divergent directions for the both non-polar faces (1100) and (1120), as well as for the both polar faces (0001) and (0001). Screw perfect dislocations were identified by propagating through the slip system (1120)(0001). The beginning of plastic deformation in single crystals is marked by pop-ins events. Such events were identified and analyzed in function of the applied force and size. The residual impressions topography and shape were analyzed by atomic force microscopy (AFM). The observed defects on the surface were propagated in a preferred direction induced by stress components around the indentation. Tensile stress generation in a certain direction increases the dislocations mobility, while compressive stress contributes to pinning regions. Stress components were identified and their magnitudes were estimated by cathode luminescence method. The polar face (0001) showed a reactive behavior; some defects produced underneath the surface were revealed by samples cleaning process.
Persson, Marcus. "Surfactants at non-polar surfaces." Doctoral thesis, KTH, Chemistry, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3444.
Full textThe aim of this thesis work was to investigate theadsorption of surfactants to different nonpolar interfaces.Particularly, the effects of the polar group and the nature ofthe hydrophobic interface were elucidated. The interfacialbehavior of the liquid-vapor interface was investigated bymeans of surface tension measurements. Here the effect of thepolar group and the hydrocarbon chain length was investigatedin a systematic manner. It was found that the shorter of thetwo chains examined, decyl, generated a larger surface pressurecontribution than the longer, dodecyl. Furthermore, the sugarbased surfactants behaved differently as compared to theethylene oxide based ones. The former could be modelled byassuming a hard disc behavior of the head group while thelatter displayed polymeric behavior. The influence of saltconcentration on the surface tension behavior of an ionicsurfactant, sodium dodecyl sulphate, was investigated. Theresult could be rationalized by employing the Gouy- Chapmanmodel to the polar region. Furthermore, mixtures of two sugarbased surfactants were investigated by surface tensionmeasurements and the adsorbed amount of the two components atthe interface atdifferent concentrations and fractions in thebulk were obtained by applying the Gibbs surface tensionequation. It was found that the molecule with the smaller headgroup adsorbed preferentially, and more so as the totalsurfactant concentration was increased. These findings could beexplained by considering the interactions generated by thedifferent head groups. The adsorption of sugar surfactants toan isolated hydrophobic surface was studied by means of wettingmeasurements and the behavior was similar to that at theliquid-vapor interface. Wetting isotherms were measured on twodifferent hydrophobic surfaces where the covalently attachedhydrophobic layers were in a crystalline and fluid state,respectively. The wetting results revealed that the sugarsurfactants anchored in the fluid hydrophobic layer. This had asignificant influence on the force profile. For example, at thecrystalline surface the surfactant monolayers were easilyremoved as the surface came into contact at relatively lowapplied loads. This was not the case when the hydrophobic layerwas in a fluid state. Here a significant fraction of thesurfactants remained between the surfaces. Disjoining pressureisotherms were measured using a sugar based surfactant thatwere thoroughly purified and compared to the as receivedsample. Even the purified sample showed a double-layer forcealthough lower as compared to the as received, one. Asignificant difference in foam stability was also observed.
Tabor, Richard F. "Surfactant kinetics in non-polar solvents." Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508096.
Full textChang, Tse Yang. "Characterisation of polar (0001) and non-polar (11-20) ultraviolet nitride semiconductors." Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/242371.
Full textEl-Agamey, Ali Abdel Ghani. "Acylperoxyl radicals and their reactions with carotenoids in polar and non-polar solvents." Thesis, Keele University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252583.
Full textEmery, Robert Michael. "Investigation into the growth of non-polar and semi-polar InGaN quantum dots." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708911.
Full textJohnston, C. F. "Characterization of (11-20) non-polar and (11-22) semi-polar GaN epitaxial films." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.605657.
Full textDerry, Matthew J. "Polymerisation-induced self-assembly in non-polar solvents." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/13620/.
Full textSchoeler, Andreas Martin. "Charge of water droplets in non-polar oils." Thesis, King's College London (University of London), 2015. http://kclpure.kcl.ac.uk/portal/en/theses/charge-of-water-droplets-in-nonpolar-oils(583a7eea-71c6-4499-a15a-f421d6e681f6).html.
Full textNowack, Rüdiger Jens. "Neutral nickel and palladium complexes as catalysts in copolymerizations of polar and non-polar monomers." [S.l. : s.n.], 2008. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-63659.
Full textPearcy, Adam C. "Non-covalent and covalent interactions between phenylacetylene and quinoline radical cations with polar and non-polar molecules in the gas phase." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5990.
Full textGunkel, Felix [Verfasser]. "The role of defects at functional interfaces between polar and non-polar perovskite oxides / Felix Gunkel." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2013. http://d-nb.info/1044492325/34.
Full textBennett, Megan. "Energy Transfer Dynamics in Collisions of Polar and Non-polar Gases with Functionalized Self-Assembled Monolayers." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/33229.
Full textMaster of Science
Gong, Yipin. "MOCVD growth and optical investigation of III-nitride materials including non-polar and semi-polar GaN." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/4991/.
Full textSutherland, Danny. "Optical characterisation of non-polar InGaN/GaN quantum wells." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/optical-characterisation-of-nonpolar-ingangan-quantum-wells(34ce6283-262b-491e-ad3d-3e2ab95cb434).html.
Full textXing, Kun. "Fabrication and overgrowth of semi-polar and non-polar GaN on sapphire for advanced III-nitride optoelectronics." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/9306/.
Full textPahlevanzadeh, Hassan. "Solubility of the toxic gases, hydrogen sulfide and sulfur dioxide in some polar and non-polar solvents." Thesis, University of Ottawa (Canada), 1986. http://hdl.handle.net/10393/5243.
Full textWaltereit, Patrick. "(Al, Ga, In)N heterostructures grown along polar and non-polar directions by plasma-assisted molecular beam epitaxy." Doctoral thesis, [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963284975.
Full textHao, Rui. "Structural and optical characterisations of defects in non-polar and semi-polar GaN epilayers and InGaN/GaN MQWs." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610548.
Full textHarper, John. "Electrochemical investigations in supercritical fluids and other non-polar media." Thesis, University of Leicester, 1998. http://hdl.handle.net/2381/30020.
Full textGreenberg, Marc Samuel. "Defining Benthic Organism Exposure: Bioavailability and Effects of Non-Polar Organics." Wright State University / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=wright1074096654.
Full textRoyal, Damian Derek. "Dielectric constants of simple gases determined using microwave cavity resonators." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313301.
Full textTruscott, Christopher Leslie. "Supramolecular chemistry at the polymer-oil interface." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/277920.
Full textMohammed, Ali Mohammed Jassim. "Optical characterisation of non polar nanostructures quantum wells ZnO/(Zn,Mg) O." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS096/document.
Full textThe zinc oxide is a promising material for the realization of optoelectronic devices in the blue-UV range. For this, it is necessary to develop hetero-structures such as ZnO / (Zn, Mg) O quantum wells in order to have better control of the properties of emissions. This work concerns the characterization of such structures grown on the A-plane (non-polar surface) of bulk ZnO. From optical spectroscopies measurements (reflectivity, continuous wave and time-resolved photoluminescence) we determined the various physical phenomena involve during the radiative recombination of the carriers in these quantum wells. At first, we studied in detail the emission of photons by the barriers of (Zn, Mg) O. Thanks to the study in temperature we showed that the optical emission of the barrier corresponds to the recombination of electron hole pairs in interactions (excitons), which are at low temperatures localized in the fluctuations of the potential. Under the influence of the temperature they delocalize and recombine as free exciton. From the detailed study of the temporal decays of photoluminescence we can demonstrate that we deal with two different excitonic states, which present different dynamics of recombination. A model is proposed that explain the various observations. The main part of this work concerns the behavior of the excitons in the quantum well. The major result is the experimental demonstration that excitonics complexes are formed at low temperature, negatively charged trion (exciton in interaction with a free electron), in this system and they are responsible for the observed luminescence. Furthermore, by varying the density of excitation we showed that biexcitons are also form (pseudo-particles formed by two excitons in interactions). The behavior in temperature of the photoluminescence obtained in different conditions of excitation demonstrates that under the influence of the thermal energy the exitonic complexes are broken to create free excitons. Measures according to the polarization of the emitted light and the temperature also allowed studying the C state of the exciton in the quantum well. The dynamics of recombination of the various excitonics complexes are examined according to the temperature
Kister, Thomas [Verfasser]. "The stability and assembly of sterically stabilized non-polar nanoparticles / Thomas Kister." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2021. http://d-nb.info/1238595510/34.
Full textHarper, Neil. "Studies on the ionisation state of subtilisin Carlsberg in non-polar organic solvents." Thesis, University of Strathclyde, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366691.
Full textSharma, Shachi Dayal Gurumayum. "Investigation of the surface interactions of polymer and surfactants in non-polar media." Thesis, University of Bristol, 2002. http://hdl.handle.net/1983/05b71826-61f9-4538-83c1-441df72cb452.
Full textOishi, Yohei. "Dynamics and structure of polybutadienyl lithium living anionic chains aggregated in non-polar solvent." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136259.
Full textMoldawer, Adam Lyle. "Growth of polar and non-polar nitride semiconductor quasi-substrates by hydride vapor phase epitaxy for the development of optoelectronic devices by molecular beam epitaxy." Thesis, Boston University, 2013. https://hdl.handle.net/2144/11151.
Full textThe family of nitride semiconductors has had a profound influence on the development of optoelectronics for a large variety of applications. However, as of yet there are no native substrates commercially available that are grown by liquid phase methods as with Si and GaAs. As a result, the majority of electronic and optoelectronic devices are grown heteroepitaxially on sapphire and SiC. This PhD research addresses both the development of polar and nonpolar GaN and AIN templates by Hydride Vapor Phase Epitaxy (HVPE) on sapphire and SiC substrates, as well as the growth and characterization of optoelectronic devices on these templates by molecular beam epitaxy (MBE). Polar and non-polar GaN templates have been grown in a vertical HVPE reactor on the C- and R-planes of sapphire respectively. The growth conditions have been optimized to allow the formation for thick (50µm) GaN templates without cracks. These templates were characterized structurally by studying their surface morphologies by SEM and AFM, and their structure through XRD and TEM. The polar C-plane GaN templates were found to be atomically smooth. However, the surface morphology of the non-polar GaN films grown on the R-plane of sapphire were found to have a facetted surface morphology, with the facets intersecting at 120° angles. This surface morphology reflects an equilibrium growth, since the A-plane of GaN grows faster than the M-planes of GaN due to the lower atomic density of the plane. For the development of deep-UV optoelectronics, it is required to grow AIGaN quantum wells on AIN templates. However, since AIN is a high melting point material, such templates have to be grown at higher temperatures, close to half the melting point of the material (1500 °C). As these temperatures cannot be easily obtained by traditional furnace heating, an HVPE reactor has been designed to heat the substrate inductively to these temperatures. This apparatus has been used to grow high-quality, transparent AIN films with a screw dislocation density of 10^6 cm^-2 on sapphire repeatedly. On such templates, both lnGaN- and AIGaN-based quantum wells (QWs) and quantum dots (QDs) were formed by MBE and were characterized. lnGaN/GaN and AIGaN/AIN QWs were grown on the non-polar GaN templates and found to emit at near green and deep UV respectively with internal quantum efficiency (IQE) close to 90%. The lnGaN GaN QWs and QDs have been investigated to understand the influence of plasmonic nanoparticles on the efficiency of corresponding green LEOS.
Wallqvist, Viveca. "Interactions between non-polar surfaces in water: Fokus on talc, pitch and surface roughness effects." Doctoral thesis, KTH, Ytkemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10283.
Full textMålet med detta avhandlingsarbete var att öka förståelsen för interaktioner mellan talkmineral och ytor, vätskor och kemikalier relevanta för industriella applikationer, såsom papper och massa. Talk används i pappers- och massaindustrin som fyllmedel, för kontroll av hartsrika (lipofila extraktivämnen) avsättningar och som bestrykningspigment. En djupare förståelse för talkinteraktioner kommer att vara användbart för att optimera dess användning. Långväga attraktiva interaktioner mellan talk och hydrofoba modellpartiklar, såväl som mellan talk och hartspartiklar, har uppmätts med hjälp av atomkraftsmikroskopi (AFM) genom att fästa kolloidala partiklar på kraftsensorn. Två metoder för att framställa partiklar gjorda av harts har utvecklats för att möjliggöra dessa studier. Hydrofoba, nanostrukturerade modellytor med ytenergier liknande de för talk har också tillverkats och deras växelverkan med hydrofoba modellpartiklar har jämförts med dem mellan talk och hydrofoba modellpartiklar. Studierna visar att talkmineral växelverkar med hydrofoba modellpartiklar, såväl som med harts, genom långväga attraktiva krafter som är betydligt starkare än den förväntade van der Waals kraften. Möjliga orsaker till de uppmätta växelverkanskrafterna diskuteras och slutsatsen blir att huvudorsaken är en attraktiv kapillärkraft som uppkommer genom att en gas-/ångkapillär bildas mellan ytorna. Kraftmätningar gjorda med hydrofoba nanostrukturerade modellytor visar att en storskalig vågighet inte nämnvärt påverkar storleken av kapillärattraktionen, men stora lokala variationer existerar. Det demonstreras att en stor variation i adhesionskraft motsvaras av en liten variation i lokal kontaktvinkel för kapillärerna på ytorna. Ytornas topografi påverkar kapillärattraktionen genom att påverka den lokala kontaktvinkeln samt genom att trefaskontaktlinjen inte kan röra sig fritt över ytan. Effekten är tydligt beroende av huruvida ytojämnheterna existerar i form av nedsänkningar eller upphöjningar. Instängd luft påverkar också pressade talktabletters uppsugningsförmåga av vatten. Vätnings- och dispergeringsmedels inverkan på växelverkan mellan talk och hydrofoba partiklar har undersökts. Resultaten visar att ett vanligt dispergeringsmedel för talk, polyakrylsyra, inte påverkar kapillärattraktionen. I själva verket tyder data på att polyakrylsyra inte adsorberas på talks basalplan. Utifrån dessa resultat dras slutsatsen att polyakrylsyra stabiliserar talkdispersioner genom att adsorbera på talkkanterna. Ett vanligt vätmedel (nonjonisk triblock sampolymer Pluronic PE6400) tar å andra sidan bort långväga kapillärattraktion. Detta antyder att egenskapen att ersätta luft på talkytan är av stor betydelse för effektiva vätmedel. Hamakerkonstanten för talk har uppskattats genom att utnyttja optiska data från ellipsometrimätningar. Det demonstreras att ett nanokristallint talkmineral kapat i olika riktningar uppvisar mycket små skillnader i Hamakerkonstant mellan de olika kristallografiska orienteringarna, medan ett mikrokristallint prov uppvisar ett betydligt högre värde. De beräknade Hamakerkonstanterna diskuteras för olika materialkombinationer relevanta för pappersindustrin, såsom cellulosa och kalciumkarbonat.
QC 20100813
Prevot, Michelle Elizabeth. "Introduction of a thermo-sensitive non-polar species into polyelectrolyte multilayer capsules for drug delivery." Phd thesis, [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980963354.
Full textJones, Christopher. "The role of water in the aggregation behaviour of surface active molecules in non-polar solvents." Thesis, University of Surrey, 2011. http://epubs.surrey.ac.uk/843130/.
Full textRosales, Daniel. "Etude des propriétés optiques de nanostructures quantiques semi-polaires et non-polaires à base de nitrure de gallium (GaN)." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS180/document.
Full textWe study the optical properties of (Al,Ga)N/GaN nanostructures grown along several crystallographic orientations. The involved orientations are: the non-polar (1-100) plane or m-plane; the semi-polar (1-101) or s-plane; and the semi-polar (11-22) plane. First, we focus on the study of the anisotropy of the optical response of quantum wells grown in m- and s-planes. Second, we evaluate the effects of the temperature on optical properties of these quantum wells by extensive utilization of the time-resolved photoluminescence technique. It allows to obtain information regarding the evolution of radiative and non-radiative phenomena with temperature. Concerning radiative decay times, we have discriminated the contributions of two recombination regimes: the recombinations of localized excitons characterized by a constant decay time; and the recombinations of free excitons whose decay time increases linearly with the temperature. For all samples studied here, the regime of recombination of localized excitons dominates at low temperature and the regime of recombination of free excitons dominates at high temperature. In addition, we characterized the quality of (Al,Ga)N/GaN interfaces by the determination of the density of localization states. The values are ranging between 10^11 cm-2 and 10^12 cm-2 in our samples. This study demonstrates that (11-22)-oriented quantum wells exhibit the lowest density, and we find that the optical properties of s-plane oriented wells are the less impacted by the non-radiative phenomena. Third, we concentrated on the characterization of nanostructures grown along (11-22) plane direction under very different growth conditions. By modifying them, it is possible to obtain either quantum dots, or quantum wires or quantum wells. The study of the exciton recombination dynamics in these (11-22)-oriented nanostructures reveals a temperature dependence of radiative decay times correlated with the dimensions of the confining potentials: it is constant for the quantum dots; proportional to square root of T for quantum wires; and linear for quantum wells. This study demonstrates the potentialities of the nanostructures grown on non-traditional orientations for optoelectronic applications
Nishat, Md Rezaul Karim. "DESIGN OF NANOSTRUCTURED ENTANGLED PHOTON PAIR GENERATOR FOR QKD APPLICATIONS." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/dissertations/1580.
Full textLowe, Douglas. "Design and implementation of a multi-component, non-equilibrium model for the study of polar stratospheric clouds." Thesis, Lancaster University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421629.
Full textMiller, John Francis. "The determination of very small electrophoretic mobilities of dispersions in non-polar media using phase analysis light scattering." Thesis, University of Bristol, 1990. http://hdl.handle.net/1983/45ef1314-ee97-4667-b179-a073b73d568d.
Full textNi, Xianfeng. "Growth and characterization of non-polar GaN materials and investigation of efficiency droop in InGaN light emitting diodes." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/2235.
Full textWu, Mo. "AlGaN/GaN Dual Channel HFETs and Realization of GaN Devices on different substrates." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/403.
Full textHillbrick, Gordon Colin, and kimg@deakin edu au. "THE LIPID COMPOSITION OF CASHMERE GOAT FIBRES." Deakin University, 1994. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20031205.162817.
Full textHuang, Pei-lun, and 黃姵綸. "Internal quantum efficiency of polar and non-polar GaN and InN." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/78s3yh.
Full text國立中山大學
物理學系研究所
97
This thesis discusses the crystal quality and transition of electrons and holes pairs by temperature- and power- dependent Photoluminescence (PL). With the PL spectra, we apply four kinds of Internal Quantum Efficiency (IQE) formulas for c- and m- plane III-nitride and discuss the differences of the four formulas. An analysis of IQE is performed and it is found for m-plane III-nitride being larger than c-plane III-nitride. This result confirms that characteristic m-plane structure can increase its radiative recombination.
Liao, Wei-Tsai, and 廖偉材. "Characteristics of polar and non-polar GaN-based films and light-emitting diodes." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/67875869478802547985.
Full text逢甲大學
材料科學所
95
Polar AlxGa1-xN (0≦x≦0.5) films and AlxGa1-xN/GaN hetero- structures were grown on (0001) and (11-20) sapphire substrates at elevated temperatures by alternate supply of trimethylgallium (TMG) with (or without) trimethylaluminum (TMA) in group III flow and ammonia (NH3) in group V stream. The optical characteristics of GaN films deposited on (11-20) sapphire substrates were found to be comparable to those of GaN films grown on (0001) sapphire substrates under the same growth conditions. It appears that an increment of V/III ratio allows to improve the morphological and optical properties of a GaN film deposited on the (11-20) sapphire substrate. The best quality GaN films were achieved at a V/III ratio of 10400 with a quenched yellow luminescence and an enhanced room temperature near band edge photoluminescence (PL) emission having a linewidth of ~ 120 meV. Besides GaN-related thin films, we also report a comparative study on the performance of InGaN/AlGaN multiple quantum well light-emitting diodes (LEDs) fabricated on (0001) and (11-20) sapphire substrates by atmospheric pressure metalorganic vapor phase epitaxy (APMOVPE), respectively. It was found that the LEDs grown on (11-20) sapphire substrates exhibited enhanced electroluminescence intensity, decreased double crystal x-ray diffraction linewidth, reduced etching pit density, and smaller ideality factor compared to those deposited on (0001) sapphire substrates. The improved LED characteristics are attributed to threading dislocation density decrement inside the LEDs due to the reduced mismatch between LED structure and (11-20) sapphire substrate. Non-polar (11-20)-oriented GaN films were grown on (1-102) sapphire substrates at elevated temperatures using low-temperature(LT)-AlN buffer layers by alternate supply of TMG and NH3 in an inductively heated quartz reactor operated at atmospheric pressure. The structural, morphological and optical characteristics of the non-polar GaN films were investigated using x-ray diffractometry, transmission electron microscopy (TEM), field emission scanning electron microscopy, and PL spectroscopy. It was found that the non-polar GaN films were mono-crystalline in nature and the surface morphologies of the films were greatly improved by introducing LT-AlN buffer layers having certain thicknesses. Various types of threading dislocations (TDs) were identified by TEM analyses. It appears that the population of TDs having ±1/3<11-20>GaN type Burgers vectors is higher than that of the pure edge TDs with ±[0001]GaN type Burgers vectors . An optimized LT-AlN buffer layer thickness was found to enhance the near bandedge PL emission and quench the yellow luminescence of the non-polar GaN film.
Huang, Po-yu, and 黃柏渝. "The photolysis difference between Polar and non-polar molecule in CH4-ice mixture." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/64394727286788084750.
Full text國立中央大學
物理研究所
98
The astronomical observation in resent years shows that the main composition of those TNOs ice are H2O, CH4 and N2. We choose these species as the ice composition and compare their difference in reaction products after exposed to and altered by VUV photons. N2 : CH4 = 1 : 1, CH4 : H2O = 1 : 1 and N2 : CH4 : H2O = 1 : 1 : 1 mixtures were prepared in gas-phase before condensation on to a precooled (16K) substrate. We use the High Flux beamline at Synchrotron Radiation Research Cente as the VUV light source. New molecules produced during photolysis were identified on the basis of their characteristic infrared feature. Quadrupole mass spectrometer was employed to detect the desorbed products during ice warming. CH4 molecules being trapped within a comparably stable N2 species in the N2-containing ices. This will induce Matrix-isolated phenomenon which blocks the radicalradical interaction between CH3 molecules and reduces the destruction rate of CH4 durung photolysis. Therefore, less C2H6 and C3H8 reaction products were detected. Moreover, lots of H atoms detached form the CH4 molecures will recombine with CCCN molecules to form HNCCC. That’s why we can only find a weak Mid-IR absorbance band of CCCN at 2194 cm^-1, but a clear absorbance feature of HNCCC at 2205 cm^-1 wavenumber. We also used the hydrogen microwave discharge lamp as the VUV light souce in the laboratory(10.2 eV). And compare the reaction products difference with the High Flux beamline (4 ∼ 20 eV ) after solid N2 + CH4 + H2O mixtures were photolysized by them. However, we didn’t find any N-containing reaction products after the ice was photolyzed by hydrogen lamp. Supposedly, the hydrogen lamp already have enough photon energy to destruct the bonds in the N2 molecules which bonding energy is about 9.76 eV. After changing the experimental methodes by photolyzing and condensing the gas-phase mixtures onto the substrate at the same time, lots of new species and products yields are found by their IR feature. And the N-containing products also shown up in those products. So we infer that the bonding energy of N2 ice is higher than 10.2 eV at least. N2-containing ice was processed by UV-photons from the High Flux beamline light source. And we find the CN^-’s IR feature at 2082cm^-1 wavenumber. However, the product was only found during ice warming process in Moore and Hudson’s experiment. By comparing the behavior of the CN^-’s IR feature during warming, we confirmed that it’s the same species that also detected in Moore and Hudson’s experiment, and believe that the CN^- will forms after VUV photolysis, but the photochemistry procedurs still needs further study to confirm. There is also lots of Nitrile (R-CN) reaction products synthesized during N2 +CH4 mixtures were processed by UV-photons. However, if there are H2O in the ice mixtures. We can’t find any Nitrile or Isonitrile yields but OCN^- will show up instead. From the above results, we found that the non-polar molecules–N2 and the polar molecules–H2O will have different influences on the products of the CH4-containing ice after photolysis. By comparing to the astronomical observations and the related publications. We confirmed that those reactions and phenomenons occuring on the TNOs. The discoveries and analysis results in this work can be used as one of reference for TNOsrelated research and other ice simulated experiments in the future.
Wu, Pei-Tsen, and 吳珮岑. "Physical properties of non-polar GaN films." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/64773875287850692593.
Full text國立中興大學
物理學系所
96
In this thesis, the physical properties, particularly the dislocation characteristics, of non-polar gallium nitride (GaN) films were investigated. Non-polar GaN films were grown on (1-102) sapphire substrates by Metal organic chemical vapor deposition (MOCVD). The as-grown non-polar GaN films were investigated by θ-to-2θ X-ray diffractometry (XRD), photoluminescence (PL) spectroscopy, transmission electron microscope (TEM) and double-crystal rocking-curve XRD. The results of TEM observations indicate that the density of threading dislocations are very high in the non-polar GaN films, and most of them are mainly Shockley partial dislocations and mixed dislocations rather than pure edge and pure screw dislocations. This result is attributed to the large difference in lattice mismatch along[1-101]sapphire||[0001]GaN and [11-20]sapphire||[1-100]GaN directions so that lots of stacking faults with Shockley partial dislocations are formed during epitaxial growth.
林薛智. "Generalized Equations for Second Virial Coefficient of Non-polar Fluids and Cross Second Virial Coefficient of Non-polar Mixtures." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/03992921846950679532.
Full text"Terahertz absorption in non-polar condensed matter systems." Thesis, 2010. http://hdl.handle.net/1911/61963.
Full textHuang, Feng-wen, and 黃鋒文. "Characterization of non-polar InGaN/GaN optoelectronic devices." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/67714126808830813008.
Full text國立成功大學
光電科學與工程研究所
96
This thesis aims at the research and fabrication of optical polarization anisotropy characteristics of light emission and absorption of optoelectronic devices fabricated on nonpolar A-plane InGaN/GaN materials. The optical polarization of light emission from the top surface and sidewall of the A- and C-plane InGaN/GaN multiple-quantum-well light-emitting diodes were investigated by measurement of polarized light power detection system and polarized electroluminescence. For the polarization of light absorption of photodetectors, the optical polarization of light absorption from the top surface of the polar C-plane and nonpolar A-plane GaN photodetectors were investigated by measurement of the responsivities for polarization detection system. The measurement of polarized light emission and absorption detection systems showed the optical polarization anisotropy characteristics of light emission from sidewall of the polar C-plane and nonpolar A-plane InGaN/GaN multiple-quantum-well light-emitting diodes, and light absorption from the top surface of the nonpolar A-plane GaN photodetectors. Furthermore, the polarization anisotropy characteristics of light emission and absorption can be enhanced by the modification of anisotropic strain and the device structure design.
Montgomery, Steven J. "Synthesis of non-polar/hydrogen bonding block copolymers." 2003. http://etda.libraries.psu.edu/theses/approved/PSUonlyIndex/ETD-430/index.html.
Full textSu, Ching-Fu, and 蘇清富. "Synthesis and Characteristics of Non-polar Polyurethane Elastomer." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/71283016472271521900.
Full text萬能科技大學
材料科技研究所
98
Nonpolar-based Polyurethane compared with polyester- and polyether-baesd Polyurethane, generally has superior hydrolytic stability, lower moisture permeability, higher oxidative stability, and improved low temperature. However, those Nonpolar-based Polyurethanes materials exhibit a lower tensile property because it is lack of strain-induced crystallization. In this study, a Nonpolar soft-segment containing polyurethane copolymer with hydrolytic and thermal stability will be synthesized using of two-step method. The results shown that the tensile strength of the copolymer was improved by the PCL polyol incorporated in the polyurethane copolymer that used PRIPLAST® as the soft segment. Furthermore, the copolymers have two characteristics of phase transition including the PRIPLAST® and PCL soft segments, and have three stages of degradation, which are associated with the soft and hard segment compositions for the phase transition and degradation.