>Magister Scientiae - MSc / Tellurium is a member of the chalcogen group in the periodic table and is known to be a better semiconductor material when compared to sulfur and selenium. By introducing tellurium into the kesterite structure there would be an improvement in the semiconducting property of the kesterite material. This research focused on incorporating tellurium into kesterite structure in order to reduce its band-gap thereby improving its light absorption and ultimately lead to a more efficient photovoltaic effect. For a typical synthesis, kesterite nanoparticles were synthesized by anion hot injection process which involved the injection of the anion precursor comprising of sulfur, selenium and tellurium in diethylene glycol into a solution containing the cation precursor which are copper (II) chloride, Zinc chloride and tin (II) chloride which are dissolved in diethylene glycol. The synthesized nanoparticles were copper zinc tin sulfide (CZTS), copper zinc tin sulfide selenide telluride (CZTSSeTe) and copper zinc tin sulfide telluride (CZTSTe). Morphological characterization of the synthesized nanoparticles was carried out by high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM) to obtain the shape of the surface and internal structure of the nanoparticles respectively. The micrograph obtained from HRSEM shows that all synthesized nanoparticles had a flower-like surface appearance which is a common morphology obtained for non-vacuum synthesized kesterite nanoparticles. The micrograph obtained from TEM showed that all nanoparticles were agglomerated and had a black surface covering which attributable to the solvent used during synthesis, washing and centrifugation. The internal structure of the synthesized nanoparticles was obtained through small angle x-ray scattering (SAXS) plot of the shapes. The shape obtained for the nanoparticles were core shell hollow sphere for CZTS, core shell dumb-bell for CZTSSeTe and solid sphere for CZTSTe.

Neste estudo foi feita uma detalhada caracterização das propriedades óticas de partículas de aerossóis biogênicos, de poluição urbana e de queimadas na bacia Amazônia. Foram utilizadas diferentes abordagens, incluindo medidas in-situ e por sensoriamento remoto em várias localidades. Radiômetros solares da rede AERONET e instrumentos de medida de absorção (Aetalômetros e MAAP) e espalhamento (Nefelômetros) foram utilizados no experimento GoAmazon2014/5 que estudou o efeito das emissões urbanas de Manaus nas propriedades de aerossóis. Em regiões impactadas pela queima de biomassa, a forçante radiativa foi quantificada através de medidas da AERONET, separando as contribuições de carbono orgânico (OC) e elementar (EC). Com base apenas nas propriedades óticas dos aerossóis, foi feita uma análise qualitativa dos tipos de aerossóis dominantes durante a queima de biomassa na Amazônia, avaliando seus impactos no balanço radiativo. O OC emitido nas queimadas tem forte efeito de resfriamento no topo da atmosfera, com uma forçante radiativa de -53 ± 17 W/m². O EC é altamente absorvedor e, apesar de estar presente em menor quantidade que o OC, apresenta um forte efeito na forçante radiativa no topo da atmosfera, tornando-a significativamente menos negativa, com efeitos de até -12 ± 9 W/m². As propriedades de absorção e espalhamento associadas com as emissões urbanas da cidade de Manaus foram analisadas. Uma significativa diferença na componente de absorção da profundidade ótica foi observada entre dois sítios localizados vento acima e vento abaixo da pluma urbana. O efeito da absorção é notável principalmente na estação chuvosa, mas também pode ser observado com as plumas de queimadas na estação seca. A partir de medidas in-situ, foi observado que o albedo de espalhamento simples (SSA) médio diminui de 0,92 ± 0,06 antes de Manaus para 0,83 ± 0,11 na região impactada pela pluma urbana durante a estação chuvosa. Medidas in-situ do coeficiente de absorção do particulado PM10 foram realizadas em paralelo com o PM2.5 durante a estação chuvosa na reserva ZF2 para análise da absorção de partículas grossas biogênicas. Em condições de dominância do particulado biogênico, a absorção em 880 nm do PM10 é cerca de 10% superior à absorção do PM2.5 no mesmo comprimento de onda, inferindo a absorção da radiação por partículas biogênicas na moda grossa. / In this study, a detailed characterization of aerosol optical properties for the biological, urban pollution and biomass burning aerosols was performed in the Amazon basin. A number of different approaches were used, including in-situ and remote sensing measurements in several locations. As part of the GoAmazon2014/5 experiment, solar radiometers from AERONET Network and in-situ instruments measuring absorption (Aethalometers and MAAP) and scattering coefficients (Nephelometers) were used to assess the effect of Manaus urban emissions on the aerosol properties. In regions heavily affected by the biomass burning events, the radiative forcing retrieved by AERONET was quantified, separating the contributions of organic carbon (OC) and elemental (EC). Based exclusively on the aerosol optical properties, a qualitative analysis of the dominant aerosol types was performed in the Amazon, assessing its impact on the radiative balance. The OC emitted from biomass burn has strong cooling effect at the top of the atmosphere, presenting an instantaneous radiative forcing of -53 ± 17 W/m². The EC is highly absorbing and, despite its lower concentration compared to the OC, showed a strong effect on the instantaneous radiative forcing at the top of the atmosphere, making it significantly less negative, with an effect up to -12 ± 9 W/m². The absorption and scattering properties associated with the urban emissions from the Manaus city were analyzed. A significant difference on the absorption optical depth was observed between two sites located upwind and downwind of the urban plume, respectively. The effect of absorption is particularly remarkable in the rainy season, but can also be observed with the biomass burning plumes during the dry season. In-situ measurements showed that the averaged single scattering albedo (SSA) decreased from 0.92 ± 0.06 upwind to 0.83 ± 0.11 downwind of Manaus urban plume during the wet season. In-situ measurements of the spectral absorption coefficient of PM10 cut size were performed in parallel with the PM2.5 during the wet season at ZF2 reserve in order to study the light absorption by biological coarse particles. In atmospheric conditions with the dominance of biological particles, the PM10 absorption at 880 nm is up to 10 % higher than the PM2.5 absorption at the same wavelength, inferring the absorption of radiation by coarse mode biological particles.

No description available.

In complex plasmonic nanostructures, the multiple metal-dielectric interfaces support several elementary modes of surface plasmon polariton. Hybridized surface plasmon polariton (HSPP) is formed due to the evanescent coupling between surface plasmon polaritons on different interfaces. In our first work, we studied the properties of HSPP in a metal-dielectric-metal waveguide with periodically varying refractive index, using Hamiltonian optics approach. We investigated the feasibility of light manipulation inside this structure by extracting the allowed phase orbits using the proposed quantization condition. Besides, the time series of position and wavevector of HSPP are simulated by solving the Hamiltonian equations. The result revealed three distinct HSPP modes formed inside the waveguide: confinement, propagation and retardation. Lastly, we investigated the usage of the proposed structure as an optical filter. / Nearly perfect absorption (NPA) refers to a phenomenon that the reflection and transmission of incident electromagnetic waves on a system are being suppressed, thus the energy of waves is being trapped and dissipated in the system. In our second work, a design of broadband, wide angle of incidence and polarization-independent nearly perfect absorber is proposed based on multiple surface plasmon resonances. The absorptance is computed to confirm NPA for TM and TE modes. Besides, the absorptance depends also on the thickness of the composite layer and this dependence is explained by the hybridized surface plasmon (HSP) formed inside the absorber. Particularly for TE mode, the broadband HSP fast wave which coupled efficiently with the incident light, can only be generated for proper thickness of the composite layer, in contrast to the previous proposal of fast wave generation mechanism using metal/epsilon-near-zero structure to yield narrow-band NPA by S.Feng. The proposed absorber can be used to construct light harvesting devices because of its high efficient energy absorption. / 在複合的等離子納米結構中的多個金屬-電介質介面能支持數個表面等離子激元(surface plasmon polariton)的基礎模態。而雜交化表面等離子激元(hybridized surface plasmon polariton)就是不同表面上的表面等離子激元因衰減性耦合而形成的。在我們第一個工作中,我們以哈密頓光學(Hamiltonian optics)研究了在有週期性折射率變化的金屬-電介質-金屬波導中雜交化表面等離子激元的特性。我們以所提出的量化條件析取出容許的相位軌跡,從而探究在此結構中操縱光波的可行性。此外,雜交化表面等離子激元的位置和波向量隨時間的變化會通過解哈密頓方程計算出來。結果顯示在此波導中,雜交化表面等離子激元有三種不同的模態:密閉,傳播,延滯。最後,我們探討了此結構作為光學過濾器的應用。 / 近完全吸收(Nearly perfect absorption)是指射在一系統上的電磁波的反射和傳輸都被壓制,而波的能量則被困鎖和消耗在系統中的一個現象。在我們第二個工作中,我們提出了一個基於多重表面等離子元共振的寬頻、廣入射角、與偏振無關的近完全吸收器設計。我們計算了吸引率以確認在TE及TM模態下的近完全吸收。此外,吸引率亦與複合層的厚度有關,而此關係能以在吸收器形成的雜交化表面等離子解釋。特別是TE模態時,能有效地與入射光耦合的寬頻雜交化表面等離子快波(Broadband HSP fastwave)只能在合適的厚度才能產生,與S.Feng所提出以金屬/近零介電常數材料結構產生快波,從而達至窄頻近完全吸收不同。因為高效能的能量吸引,我們提出的吸收器能作建構光收集裝置之用。 / Lee, Sze Fung = 在等離子吸收器中基於多重表面等離子元共振的寬頻近完全吸收 / 李時鋒. / Thesis M.Phil. Chinese University of Hong Kong 2014. / Includes bibliographical references (leaves 58-62). / Abstracts also in Chinese. / Title from PDF title page (viewed on 24, October, 2016). / Lee, Sze Fung = Zai deng li zi xi shou qi zhong ji yu duo chong biao mian deng li zi yuan gong zhen de kuan pin jin wan quan xi shou / Li Shifeng. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

For organic solar cells: exciton generation, exciton diffusion, charge transfer, and charge transport of a photoactive layer are the important factors in photocurrent generation. In this thesis, we blend small molecular material tris(8-hydroxyquinoline)aluminum (Alq3) into poly [ 2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene ]:short-length carbon nanotubes (MEH-PPV:SLCNTs) films to increase the light absorption, in the range of 300 to 450 nm, and hence increase the exciton generation. The comparison of the photoluminescence (PL) of a donor with that of the Donor-Acceptor composite provides an important and simple method to detect the charge transfer phenomenon. Furthermore, the degree of photoluminescence quenching may be representative of the efficiency of charge transfer. [1-6] Using this concept and method, we obtain that at the mix ratio of 1:0.5 (MEH-PPV:SLCNTs) by weight, 33 wt.% SLCNTs, probably have the maximum of charge transfer efficiency. To further check that at this concentration might have the maximum efficiency of the charge transfer, we also used time-resolved fluorescence spectrometer to measure the fluorescence lifetime of MEH-PPV. The shortest MEH-PPV fluorescence lifetime of 0.15 ns at 33 wt.% SLCNTs corresponds with our conjecture. For simplicity to discuss next experiment results, we make two assumptions at this mix ratio: (1) The efficiency of the charge transfer process is very high, so the competing processes can be neglected. Because of the forward electron transfer process occurs in the sub-picosecond time domain; (2) The exciton diffusion efficiency is approximately unity in the bulk heterojunction photoactive layer. Based on this assumption, the higher degree of photoluminescence quenching of MEH-PPV:Alq3 and MEH-PPV:Alq3:SLCNTs system demonstrates blending alq3 into MEH-PPV:SLCNTs films maybe can increase the charge photogeneration. The PL and UV/VIS absorption spectra are employed to examine the energy transfer process between Alq3 and MEH-PPV. When MEH-PPV:Alq3 films are excited at the wavelength of 380 nm which is in the main absorption region of Alq3, the increase in PL intensity of MEH-PPV at 577nm and the absent emission spectra of Alq3 illustrates Alq3 transfer its energy to MEH-PPV. By scanning electron microscopy, we observed that the surface pinholes became less than that of MEH-PPV films. This result suggests the devices utilizing the MEH-PPV:Alq3 composites as electron donor materials may have smaller electrode contact resistance. From all above the experiment data, we believe using MEH-PPV:Alq3:SLCNT as a photoactive layer perhaps can enhance the device performance.

Estimating with precision coastal marine properties such as primary production, particulate and dissolved carbon, and red tide concentrations is a challenging but important part of marine research. It benefits not only the local communities, but also provides an important input to various global biogeochemical modeling efforts. Due to the complexity of coastal environments resulting from temporal variability of tidal and riverine influences, it is useful to develop and deploy an automated sensor network that provides real-time feedback. It can be used to validate remote sensing models to retrieve in-water constituents, and provide calibration and validation for atmospheric correction of satellite sensors. For turbid waters, satellite observations in the infrared part of the spectrum can not be used to estimate atmospheric aerosol concentration because the water is not black as is found for clearer waters. This research contribution introduces a modeling effort for a turbid coastal harbor area using a semi-analytical hyperspectral remote sensing algorithm for Case 2 waters to process data from the Autonomous Marine Optical System (AMOS). Retrieved results are then compared with field sample measurements showing satisfactory closure between measurements and theory. A time series of AMOS data over a one-month time span is examined, revealing significant variations in biological activity. A sensitivity analysis of the model is performed to expose the limitations and possible improvements to AMOS measurements in the future.

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains viii, 71 p. : ill. Includes abstract. Includes bibliographical references (p. 70-71).

Neste estudo foi feita uma detalhada caracterização das propriedades óticas de partículas de aerossóis biogênicos, de poluição urbana e de queimadas na bacia Amazônia. Foram utilizadas diferentes abordagens, incluindo medidas in-situ e por sensoriamento remoto em várias localidades. Radiômetros solares da rede AERONET e instrumentos de medida de absorção (Aetalômetros e MAAP) e espalhamento (Nefelômetros) foram utilizados no experimento GoAmazon2014/5 que estudou o efeito das emissões urbanas de Manaus nas propriedades de aerossóis. Em regiões impactadas pela queima de biomassa, a forçante radiativa foi quantificada através de medidas da AERONET, separando as contribuições de carbono orgânico (OC) e elementar (EC). Com base apenas nas propriedades óticas dos aerossóis, foi feita uma análise qualitativa dos tipos de aerossóis dominantes durante a queima de biomassa na Amazônia, avaliando seus impactos no balanço radiativo. O OC emitido nas queimadas tem forte efeito de resfriamento no topo da atmosfera, com uma forçante radiativa de -53 ± 17 W/m². O EC é altamente absorvedor e, apesar de estar presente em menor quantidade que o OC, apresenta um forte efeito na forçante radiativa no topo da atmosfera, tornando-a significativamente menos negativa, com efeitos de até -12 ± 9 W/m². As propriedades de absorção e espalhamento associadas com as emissões urbanas da cidade de Manaus foram analisadas. Uma significativa diferença na componente de absorção da profundidade ótica foi observada entre dois sítios localizados vento acima e vento abaixo da pluma urbana. O efeito da absorção é notável principalmente na estação chuvosa, mas também pode ser observado com as plumas de queimadas na estação seca. A partir de medidas in-situ, foi observado que o albedo de espalhamento simples (SSA) médio diminui de 0,92 ± 0,06 antes de Manaus para 0,83 ± 0,11 na região impactada pela pluma urbana durante a estação chuvosa. Medidas in-situ do coeficiente de absorção do particulado PM10 foram realizadas em paralelo com o PM2.5 durante a estação chuvosa na reserva ZF2 para análise da absorção de partículas grossas biogênicas. Em condições de dominância do particulado biogênico, a absorção em 880 nm do PM10 é cerca de 10% superior à absorção do PM2.5 no mesmo comprimento de onda, inferindo a absorção da radiação por partículas biogênicas na moda grossa. / In this study, a detailed characterization of aerosol optical properties for the biological, urban pollution and biomass burning aerosols was performed in the Amazon basin. A number of different approaches were used, including in-situ and remote sensing measurements in several locations. As part of the GoAmazon2014/5 experiment, solar radiometers from AERONET Network and in-situ instruments measuring absorption (Aethalometers and MAAP) and scattering coefficients (Nephelometers) were used to assess the effect of Manaus urban emissions on the aerosol properties. In regions heavily affected by the biomass burning events, the radiative forcing retrieved by AERONET was quantified, separating the contributions of organic carbon (OC) and elemental (EC). Based exclusively on the aerosol optical properties, a qualitative analysis of the dominant aerosol types was performed in the Amazon, assessing its impact on the radiative balance. The OC emitted from biomass burn has strong cooling effect at the top of the atmosphere, presenting an instantaneous radiative forcing of -53 ± 17 W/m². The EC is highly absorbing and, despite its lower concentration compared to the OC, showed a strong effect on the instantaneous radiative forcing at the top of the atmosphere, making it significantly less negative, with an effect up to -12 ± 9 W/m². The absorption and scattering properties associated with the urban emissions from the Manaus city were analyzed. A significant difference on the absorption optical depth was observed between two sites located upwind and downwind of the urban plume, respectively. The effect of absorption is particularly remarkable in the rainy season, but can also be observed with the biomass burning plumes during the dry season. In-situ measurements showed that the averaged single scattering albedo (SSA) decreased from 0.92 ± 0.06 upwind to 0.83 ± 0.11 downwind of Manaus urban plume during the wet season. In-situ measurements of the spectral absorption coefficient of PM10 cut size were performed in parallel with the PM2.5 during the wet season at ZF2 reserve in order to study the light absorption by biological coarse particles. In atmospheric conditions with the dominance of biological particles, the PM10 absorption at 880 nm is up to 10 % higher than the PM2.5 absorption at the same wavelength, inferring the absorption of radiation by coarse mode biological particles.

This study reports on a variety of experimental and theoretical studies conducted in ZnSe, CdTe, and in semiconductor-doped glasses. The transient picosecond degenerate four-wave mixing (DFWM) experiments performed in these II-VI direct-gap semiconductors are part of our efforts to understand the picosecond dynamics of the free-carriers generated via two and three-photon absorption.

Luk, Wai Chun = / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 101-108). / Abstracts in English and Chinese. / Luk, Wai Chun = / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Theoretical Background --- p.5 / Chapter 2.1 --- Maxwell´ةs equations in matter --- p.5 / Chapter 2.2 --- Dielectric constant of materials --- p.8 / Chapter 2.3 --- Dispersion relation of surface plasmon polaritons --- p.10 / Chapter 2.4 --- Excitation of surface plasmon polaritons --- p.16 / Chapter 2.4.1 --- Prism coupling --- p.17 / Chapter 2.4.2 --- Grating coupling --- p.21 / Chapter 2.5 --- Diffraction of light in gratings --- p.26 / Chapter 2.6 --- Applications --- p.27 / Chapter 3 --- Analysis Methods --- p.29 / Experimental Section --- p.29 / Chapter 3.1 --- Interference Lithography --- p.29 / Chapter 3.2 --- Gold grating fabrication --- p.32 / Chapter 3.2.1 --- Substrate preparation --- p.33 / Chapter 3.2.2 --- Photoresist preparation --- p.34 / Chapter 3.2.3 --- Spin coating of omnicoat and photoresist --- p.35 / Chapter 3.2.4 --- Interference lithography set-up and procedures --- p.35 / Chapter 3.2.5 --- The post-exposed treatments --- p.37 / Chapter 3.2.6 --- The optimal exposure time calibration --- p.37 / Chapter 3.2.7 --- Gold thin film deposition --- p.39 / Chapter 3.2.8 --- Typical gold grating sample --- p.41 / Chapter 3.3 --- Measurement system --- p.41 / Chapter 3.3.1 --- The angle dependent reflectivity measurement --- p.42 / Chapter 3.3.2 --- Data presentation of a typical band structure --- p.45 / Chapter 3.3.3 --- Periodicity measurement of the grating samples --- p.48 / Chapter 3.3.4 --- Diffracted intensity measurement of gratings --- p.52 / Chapter 3.3.5 --- Data presentation of the angle dependent diffracted intensity measurement --- p.53 / Calculation Section --- p.54 / Chapter 3.4 --- RCWA simulations --- p.54 / Chapter 3.4.1 --- The dispersion relation --- p.56 / Chapter 3.4.2 --- The diffracted intensity --- p.56 / Chapter 3.4.3 --- The field pattern graphs --- p.57 / Chapter 4 --- Resonance modes in one-dimensional gold gratings --- p.60 / Chapter 4.1 --- Structure of the gold grating samples --- p.61 / Chapter 4.2 --- Results of angle dependent reflectivity --- p.63 / Chapter 4.2.1 --- Surface Plasmon Polaritons (SPPs) --- p.65 / Chapter 4.2.2 --- Wood´ةs anomaly --- p.65 / Chapter 4.2.3 --- Waveguide Resonance (WG) --- p.67 / Chapter 4.2.4 --- Coupling of SPPs and WG --- p.67 / Chapter 4.3 --- Results of angle dependent diffracted intensity measurement --- p.68 / Chapter 4.4 --- Basic properties of SPPs and WG modes by RCWA --- p.73 / Chapter 4.4.1 --- Sample 1 (D = 40 nm) --- p.74 / Chapter 4.4.1(a) --- λ = 980 nm of Sample 1 --- p.75 / Chapter 4.4.1(b) --- λ = 633 nm of Sample 1 --- p.81 / Chapter 4.4.2 --- Sample 2 (D = 390 nm) --- p.83 / Chapter 4.4.2(a) --- λ = 980 nm of Sample 2 --- p.85 / Chapter 4.4.2(b) --- λ = 725 nm of Sample 2 --- p.87 / Chapter 4.4.2(c) --- λ = 633 nm of Sample 2 --- p.92 / Chapter 4.5 --- Summary --- p.97 / Chapter 5 --- Conclusions --- p.99 / Bibliography --- p.101