by S.W. Wong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 76-77). / by S.W. Wong. / Title Page --- p.i / Dedication --- p.ii / Acknowledgments --- p.iii / Abstract --- p.iv / Table of Contents --- p.v / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- A Brief Introduction to Nonlinear Optics --- p.7 / Chapter Chapter 3 --- Experimental Measurement of the First Hyperpolarizability β for pNA by Hyper-Rayleigh Scattering in Solution --- p.24 / Chapter 3.1 --- Introduction --- p.24 / Chapter 3.2 --- Theory of Measurement of β by HRS --- p.26 / Chapter 3.3 --- Experimental Setup --- p.31 / Chapter 3.4 --- Preparation of Sample --- p.34 / Chapter 3.5 --- Results --- p.35 / Chapter Chapter 4 --- Studies of Depolarization Ratio in HRS --- p.44 / Chapter 4.1 --- Background --- p.44 / Chapter 4.2 --- Theory --- p.45 / Chapter 4.3 --- Results --- p.55 / Chapter 4.4 --- Discussion and Conclusion --- p.57 / Chapter Chapter 5 --- Measurement on other Nonlinear Optical Compounds --- p.63 / Chapter Chapter 6 --- Conclusion --- p.73 / References --- p.76

Nesta tese apresentamos uma extensão da técnica de espalhamento hiper-Rayleigh (HRS) e sua aplicação para o estudo dos mecanismos que interferem na primeira hiperpolarizabilidade molecular (). Utilizamos um laser Nd:YAG, Q-switched e mode-locked como bombeio para excitar as amostras. Este laser emite pulsos de 100 ps modulados por uma envoltória de Q-switch. A saída é uma seqüência de pulsos com intensidades que acompanham a forma da envoltória. Usamos este trem de pulsos para excitar as amostras na medida de espalhamento hiper-Rayleigh, e um sistema de detecção com resolução temporal suficiente para resolver cada pulso independentemente. Esta modalidade de bombeio permitiu eliminar o controle mecânico da intensidade, o que reduziu o tempo necessário para a medida e melhorou a estabilidade nas condições experimentais. O método com trem de pulsos proporciona meios de identificar contribuições luminescentes e evitar valores superestimados para a primeira hiperpolarizabilidade. Realizamos testes medindo a molécula de paranitroanilina em vários solventes e verificamos muito boa reprodutibilidade dos valores da literatura. Comparamos os resultados medidos com valores calculados a partir do método de Hartree-Fock e corrigimos o engrandecimento por ressonância utilizando um modelo de dois níveis. A comparação entre valores teóricos e experimentais teve uma diferença média de 15%. Um estudo análogo para a molécula de dianilina não reproduziu os valores experimentais e atribuímos a falha à inaplicabilidade do modelo de dois níveis para medidas no regime ressonante. Também estudamos a primeira hiperpolarizabilidade nas porfirinas TDMImP e TPPS4, sob a forma base livre e formando complexos com Zn2+, Fe3+ e Mn3+. Para a TPPS4 estendemos o estudo para observar os efeitos da protonação na base livre e da formação de oxo dímeros na FeTPPS4 e as alterações causadas pela presença de micelas de CTAB. A comparação direta entre os resultados é dificultada em muitos casos pela diferença no engrandecimento por ressonância. Foi possível verificar que a presença de micelas tem o efeito de diminuir o valor de na H2TPPS4 pH 7. As medidas de HRS em ambiente ácido (pH 4) corroboram com a literatura, indicando que a ocorre desprotonação na presença de micelas. Um estudo teórico e experimental dos três isômeros do aminofenol permitiu analisar os efeitos da posição relativa dos grupos radicais e do comprimento da conjugação sobre a primeira hiperpolarizabilidade. Verificamos que a alteração no caráter doador/aceitador para diferentes posições dos grupos radicais tem influência maior no valor de do que o comprimento da conjugação. Utilizamos compostos com o ligante salen, com grupos laterais etano e DR1 e com ligantes H2, Cu2+, Ni2+ e VO2+, para estudar como os diferentes grupos e complexos refletem diferenças no valor de . Foi possível verificar que diferentemente da absorção linear e da seção de choque para dois fótons, o ligante com grupos radicais DR1 causam um aumento na primeira hiperpolarizabilidade que é muito maior do que a soma das contribuições individuais. Os complexos têm primeiras hiperpolarizabilidades maiores do que o ligante com H2 e a comparação entre os dois grupos com diferentes radicais mostra que existe uma correlação entre os aumentos causados por diferentes complexos. / This thesis reports an extension of the Hyper-Rayleigh scattering technique (HRS) and its application to study the mechanisms that contribute to the molecular first hyperpolarizabilities (). We use a Nd:YAG laser, Q-switched and mode-locked, as pumping beam to excite the samples. The laser delivers 100 ps pulses modulated by a Q-switch envelope, and the output is a pulse sequence which intensities follow the shape of the envelope. This pulse train is used to excite the samples in a Hyper-Rayleigh scattering experiment and the signal for each mode-lock pulse is detected independently. This modality of pumping allows the removal of the mechanical intensity control, therefore reducing measurement time and improved experimental stability. The method with pulse train also provides means to identify luminescent contributions and avoid overestimated values for the first hyperpolarizability. We performed test measurements with para-nitroaniline in several solvents and verified very good reproducibility of literature values. We also compared the measured and calculated values, obtained with the Hartree-Fock method and corrected for resonance enhancement with a two level model. The comparison between theoretical and experimental values results in an average difference of 15%. Similar studies for the dianiline molecule failed to reproduce experimental values and we attributed the failure to the inadequacy of the of the two-level model to correct resonance enhancement. We also studied the first hyperpolarizability of the TDMImP and TPPS4 porphyrins, in the free-base form and in complex with Zn2+, Fe3+ and Mn3+. For TPPS4 we extended the study to observe the protonação effects in the free-base and the formation of oxo dimmers in FeTPPS4 complexes. The comparison between results from different compounds is hindered in most cases by different contributions from resonance enhancement. However, it was possible to verify that the presence of micelles has the effect of reducing the value of on H2TPPS4 pH 7. The HRS measurements in acid environment (pH 4) corroborates with the literature, indicating that desprotonation occurs in the presence of CTAB micelles. A theoretical and experimental study of three aminofenol isomers allowed to verify the effects of the relative positions of radical groups and the conjugation length on the first hyperpolarizability. The results show that in this case the change in the donor/acceptor character for different positions of the radical groups is more important than the increase in one unit in the conjugation length. We also studied compounds with the salen ligant, observing the effects of different lateral groups (ethane and DR1) and different complexes (H2, Cu2+, Ni2+ and VO2+) on the value of . It was possible to verify that, differently than the linear absorption the two-photon cross section, the compounds with DR1 shows an increase in the first hyperpolarizability that is much larger than the sum of the individual contributions of DR1 groups. The metal complexes have larger first hyperpolarizabilities than the ligant and the enhancement produced by different complexes follows the same pattern for both radical groups. Even after the strong increase in produced by the DR1 group, the much weaker effect of the complexes is preserved and measurable.

In the last few years, interest in polymer optical fibers (POF) has increased because of their low cost, easy handling and good flexibility even at large diameters. Moreover, optical cables do not have the problem of electromagnetic interference, which gives, for instance, the problem of cross-talk in copper telephone cables. In the usage of current communication and computer systems the yield has gained a big importance and it has seen from studies that light scattering loss is the only loss, which cannot be eliminated entirely. Besides, this loss causes its attenuation loss intrinsically and determines the lower limit of loss in the POF. In this work, the importance and the dependencies of light scattering were studied, and calculations were done in order to find more appropriate polymer for using as core material of POFs. For this aim, a computer program that calculates the light scattering loss of several amorphous polymers and plots the graph of isotropic scattering loss versus isothermal compressibility and total attenuation loss versus wavelength was written.

LIDAR, an acronym for LIght Detection And Ranging, is a system used for studying the scattering of laser light incident on a parcel of air. This thesis investigates the atmosphere above the Durban region using two atmospheric LIDARs, referred to, in this study, as the "old LIDAR" and the "new LIDAR". The old LIDAR was used in a campaign of observation from July to October 1997 in a study of aerosol concentrations over Durban. This thesis will focus on, among other things, the local aerosol profiles for low altitude (0 to 10 km) and high altitude (10 to 35 km). In particular, the focus will shift on any long persistence in this region (it was found that the aerosol layer observed by M. Kuppen (1996) on June 1994 at 25 km may have moved to the higher altitude of 28 km in October 1997. This may be explained by stratospheric upwelling, carrying the layer to higher altitude. These aerosols are known to influence the local climate). This investigation will give some useful insight into the local atmospheric dynamics. The new LIDAR system (Rayleigh-Mie LIDAR) has been used to measure atmospheric temperatures from 20 to 60 km as well as aerosol extinction coefficients from 15 to 40 km. Height profiles of temperature have been measured by assuming that the LIDAR returns are solely due to Rayleigh scattering by molecular species and that the atmosphere obeys the perfect gas law and is in hydrostatic equilibrium (Hauchecorne and Chanin 1980). Since its installation in April 1999, the new LIDAR has been used to monitor stratospheric temperatures and aerosol concentrations from 10 to 40 km. In this study, we discuss in chapter 7 the results of a validation campaign conducted during the period of April 1999 to December 2000. Average monthly LIDAR temperatures are computed from April 1999 to December 1999 and compared with radiosonde temperatures obtained from the South African Weather Service (SAWS) at Durban. The monthly LIDAR temperature profiles over two years (1999 and 2000) were also computed and compared with the climatological model Cospar International Reference Atmosphere (CIRA)-1986 and with the average monthly European Centre for Medium Range Weather Forecast (ECMWF) temperatures . The results show that there is good agreement between LIDAR and SAWS radiosonde temperatures in the 20 and 30 km altitude range. Between 20 and 40 km, the monthly LIDAR temperatures agree closely with the CIRA-86 and ECMWF profiles. However, during winter, in the altitude range 40 to 60 km, LIDAR temperatures are warmer than CIRA-1986 and ECMWF temperatures, and they show large variability. These variations could be due to relatively fast transient phenomena like gravity waves or planetary waves propagating vertically in the stratosphere. As part of the validation process, the aerosol extinction coefficients retrieved from the LIDAR data have also been compared with the extinction coefficients measured by Stratospheric Aerosol and Gas Experiment (SAGE) II close to the LIDAR location and on coincident days. Appendix E of this thesis also investigates the concept of refraction by atmospheric gases as applied to gas lenses. A simple spinning pipe gas lens (SPGL) has been used as the objective lens of a camera to take pictures of the moon and sun spots. The SPGL is a varifocal length lens which depends on the temperature of the pipe and the angular velocity at which it spins. For our purpose a focal length of 8 m has been used. The moon pictures are compared with a lunar map so as to identify the maria. / Thesis (Ph.D.)-University of Natal, Durban, 2002.

A new type Rayleigh scattering of Mössbauer radiation (RSMR) spectrometer was developed, which due to favorable time scale of scattering process is suitable for the studies of complicated dynamics of biomolecules (not containing mössbauer nucleus) Densely packed iron nanowire arrays were created using template method of aluminum anodic oxide (AAO). Pore size and density of AAO template can be easily controlled by adjusting anodizing conditions. Shape and diameter of nanowires appear to be exact replicas of AAO pores. the effectiveness of different aqueous electrolytes used in nanowire deposition was investigated. Growth rate in different electrolytes was determined to be 52±2 nm/min. and 11,8±0,6 nm/min. This study has demonstrated the effects of aging of iron nanowires embedded within the pores of the AAO template. the influence of annealing parameters on the chemical composition of iron nanowires was investigated. CEMS studies have revealed. / Panaudojus puslaidininkinį γ-kvantų detektorių sukurtas naujo tipo Mesbauerio spinduliuotės Relėjaus sklaidos spektrometras, kuris dėl tinkamo γ-kvantų sklaidos laiko gali būti taikomas konformacinių judesių biologiniuose objektuose ir polimeruose, neturinčiuose mesbauerinių branduolių, tyrimams. Paruošti geležies nanosiūlų kolonijos, esančias aliuminio anodinio oksido (AAO) matricoje. Parenkant anodavimo sąlygas galima kontroliuoti, susidariusio tvarkingo porėto AAO, porų dydį ir tankį. Pagamintos AAO matricos užpildytos geležimi, taip susiformuoja žinomo dydžio nanosiūlai, kurių diametras atitinka porų diametrą. Palygintas vandeninių elektrolitų, skirtų užpildyti AAO poras, efektyvumas. Augimo greitis skirtinguose elektrolituose yra 52 ± 2 nm/min. ir 11,8 ± 0,6 nm/min. Nustatyti geležies nanosiūlų cheminės sudėties pokyčiai susidarymo ir senėjimo metu. Eksperimentiniais tyrimais įrodyta, kad geležies nanosiūlai AAO matricoje oksiduojasi ne visu tūriu, bet nuo atvirojo galo. Pakaitinus (daugiau nei 200 °C) metalinius nanosiūlus įkalintus AAO matricose, šie reaguoja su anodinio aliuminio oksidu ir sudaro špinelines struktūras.

Nesta tese apresentamos uma extensão da técnica de espalhamento hiper-Rayleigh (HRS) e sua aplicação para o estudo dos mecanismos que interferem na primeira hiperpolarizabilidade molecular (). Utilizamos um laser Nd:YAG, Q-switched e mode-locked como bombeio para excitar as amostras. Este laser emite pulsos de 100 ps modulados por uma envoltória de Q-switch. A saída é uma seqüência de pulsos com intensidades que acompanham a forma da envoltória. Usamos este trem de pulsos para excitar as amostras na medida de espalhamento hiper-Rayleigh, e um sistema de detecção com resolução temporal suficiente para resolver cada pulso independentemente. Esta modalidade de bombeio permitiu eliminar o controle mecânico da intensidade, o que reduziu o tempo necessário para a medida e melhorou a estabilidade nas condições experimentais. O método com trem de pulsos proporciona meios de identificar contribuições luminescentes e evitar valores superestimados para a primeira hiperpolarizabilidade. Realizamos testes medindo a molécula de paranitroanilina em vários solventes e verificamos muito boa reprodutibilidade dos valores da literatura. Comparamos os resultados medidos com valores calculados a partir do método de Hartree-Fock e corrigimos o engrandecimento por ressonância utilizando um modelo de dois níveis. A comparação entre valores teóricos e experimentais teve uma diferença média de 15%. Um estudo análogo para a molécula de dianilina não reproduziu os valores experimentais e atribuímos a falha à inaplicabilidade do modelo de dois níveis para medidas no regime ressonante. Também estudamos a primeira hiperpolarizabilidade nas porfirinas TDMImP e TPPS4, sob a forma base livre e formando complexos com Zn2+, Fe3+ e Mn3+. Para a TPPS4 estendemos o estudo para observar os efeitos da protonação na base livre e da formação de oxo dímeros na FeTPPS4 e as alterações causadas pela presença de micelas de CTAB. A comparação direta entre os resultados é dificultada em muitos casos pela diferença no engrandecimento por ressonância. Foi possível verificar que a presença de micelas tem o efeito de diminuir o valor de na H2TPPS4 pH 7. As medidas de HRS em ambiente ácido (pH 4) corroboram com a literatura, indicando que a ocorre desprotonação na presença de micelas. Um estudo teórico e experimental dos três isômeros do aminofenol permitiu analisar os efeitos da posição relativa dos grupos radicais e do comprimento da conjugação sobre a primeira hiperpolarizabilidade. Verificamos que a alteração no caráter doador/aceitador para diferentes posições dos grupos radicais tem influência maior no valor de do que o comprimento da conjugação. Utilizamos compostos com o ligante salen, com grupos laterais etano e DR1 e com ligantes H2, Cu2+, Ni2+ e VO2+, para estudar como os diferentes grupos e complexos refletem diferenças no valor de . Foi possível verificar que diferentemente da absorção linear e da seção de choque para dois fótons, o ligante com grupos radicais DR1 causam um aumento na primeira hiperpolarizabilidade que é muito maior do que a soma das contribuições individuais. Os complexos têm primeiras hiperpolarizabilidades maiores do que o ligante com H2 e a comparação entre os dois grupos com diferentes radicais mostra que existe uma correlação entre os aumentos causados por diferentes complexos. / This thesis reports an extension of the Hyper-Rayleigh scattering technique (HRS) and its application to study the mechanisms that contribute to the molecular first hyperpolarizabilities (). We use a Nd:YAG laser, Q-switched and mode-locked, as pumping beam to excite the samples. The laser delivers 100 ps pulses modulated by a Q-switch envelope, and the output is a pulse sequence which intensities follow the shape of the envelope. This pulse train is used to excite the samples in a Hyper-Rayleigh scattering experiment and the signal for each mode-lock pulse is detected independently. This modality of pumping allows the removal of the mechanical intensity control, therefore reducing measurement time and improved experimental stability. The method with pulse train also provides means to identify luminescent contributions and avoid overestimated values for the first hyperpolarizability. We performed test measurements with para-nitroaniline in several solvents and verified very good reproducibility of literature values. We also compared the measured and calculated values, obtained with the Hartree-Fock method and corrected for resonance enhancement with a two level model. The comparison between theoretical and experimental values results in an average difference of 15%. Similar studies for the dianiline molecule failed to reproduce experimental values and we attributed the failure to the inadequacy of the of the two-level model to correct resonance enhancement. We also studied the first hyperpolarizability of the TDMImP and TPPS4 porphyrins, in the free-base form and in complex with Zn2+, Fe3+ and Mn3+. For TPPS4 we extended the study to observe the protonação effects in the free-base and the formation of oxo dimmers in FeTPPS4 complexes. The comparison between results from different compounds is hindered in most cases by different contributions from resonance enhancement. However, it was possible to verify that the presence of micelles has the effect of reducing the value of on H2TPPS4 pH 7. The HRS measurements in acid environment (pH 4) corroborates with the literature, indicating that desprotonation occurs in the presence of CTAB micelles. A theoretical and experimental study of three aminofenol isomers allowed to verify the effects of the relative positions of radical groups and the conjugation length on the first hyperpolarizability. The results show that in this case the change in the donor/acceptor character for different positions of the radical groups is more important than the increase in one unit in the conjugation length. We also studied compounds with the salen ligant, observing the effects of different lateral groups (ethane and DR1) and different complexes (H2, Cu2+, Ni2+ and VO2+) on the value of . It was possible to verify that, differently than the linear absorption the two-photon cross section, the compounds with DR1 shows an increase in the first hyperpolarizability that is much larger than the sum of the individual contributions of DR1 groups. The metal complexes have larger first hyperpolarizabilities than the ligant and the enhancement produced by different complexes follows the same pattern for both radical groups. Even after the strong increase in produced by the DR1 group, the much weaker effect of the complexes is preserved and measurable.

Neste trabalho, estudamos as propriedade ópticas da tetrapiridilporfirina (TPyP), usando clorofórmio como sol vente. Para a caracterização óptica linear foram medidos os espectros de fluorescência e absorbância, tendo este último nos permitido determinar a seção de choque para o estado fundamental com radiação incidente em 532 nm. Usamos a técnica de varredura Z com trem de pulsos (VZTP) para medirmos a absorção não linear da TPyP, em 532 nm, e determinamos, através de um modelo fenomenológico de cinco níveis, vários parâmetros espectroscópicos tais como seções de choques e tempos de vida dos estados. Além disso, com a utilização da técnica de espalhamento hiperRayleigh (HRS) medimos a primeira hiperpolarizabilidade da TPyP, dissolvida em clorofórmio em 1064 nm usando, como material de referência, a p-nitroanilina (PN A), diluída em metanol. / This work reports on the optical properties of the tetrakis(pyridil)porphyrin (TPyP). In order to perform the linear optical characterization, fluorescence and absorbance spectra were obtained, where the latter allowed the determination of the cross-section for the ground state with incident radiation at À = 532 nm. We used the Zscan tecnique with pulse trains (ZSPT) to measure the nonlinear absorption of TPyP, at 532 nm, and we managed to determine, through a phenomenological five levels model, several spectroscopic parameters such as cross-sections and lifetime of the states. Moreover, we measured the first hyperpolarizability of TPyP dissolved in chloroform, at À = 1064 nm, using the Hyper-Rayleigh scattering (HRS) technique. The reference material used for HRS measurements was p-nitroaniline (PNA) dissolved in methanol.

No description available.

Orientador: Gustavo Fraidenraich / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-18T12:42:39Z (GMT). No. of bitstreams: 1 CalderonInga_MitchellOmar_M.pdf: 4733718 bytes, checksum: 3e71582f5976b8ea4eeca1018833957d (MD5) Previous issue date: 2011 / Resumo: Neste trabalho, propomos um esquema novo baseado na diversidade por cooperação de usuários. Os resultados apresentados mostram que o novo esquema de cooperação consegue um aumento substancial da taxa de dados, mantendo a média da probabilidade de erro de bit perto dos valores obtidos no artigo User Cooperation Diversity-Part II escrito por Sendonaris et al. Em particular, apresentamos uma análise de desempenho usando uma implementação CDMA (code division multiple access) convencional para dois usuários. Além disso, uma expressão exata para a probabilidade média de erro de bit foi obtida para o detector ?-MRC (maximal-ratio combining), proposto por Sendonaris et al., para um canal com desvanecimento Rayleigh. Dada a complexidade da expressão exata, uma aproximação muito boa foi obtida para calcular a probabilidade média de erro de bit para qualquer esquema de alocação de potência. Nossas expressões permitem investigar os possíveis ganhos e as situações onde a cooperação pode ser benéfica / Abstract: In this work, we propose a new scheme based on user cooperation diversity. The results presented here show that the new scheme of cooperation achieves substantial increase of data rate, keeping the average bit error probability close to values obtained in the paper User Cooperation Diversity-Part II written by Sendonaris et al. In particular, we present performance analysis using conventional CDMA (code division multiple access) implementation for two users. Moreover, an exact expression for the average bit error probability was obtained for the ?-MRC (maximal-ratio combining) detector, proposed in Sendonaris et al., under Rayleigh fading channel. Given the complexity of the exact expression, a very good approximation was obtained to calculate the average bit error probability for any power allocation scheme. Our expressions allow to investigate the possible gains and situations where cooperation can be beneficial / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

The financial requirements between fiber optic sensors and conventional sensors are gradually declining, which, despite many advatages and wide range of applicationas, has slowed down the demand for these sensors. With the demand for fiber optic sensors also grow the requirements for the parameters of these sensors. This thesis deals with distributed temperature fiber optic sensors. Non--linear phenomen in optical fibers, such as Raman scattering is used for measuring with these sensors. This scatterin was used to obtain information about temperature, which effected the optical cable under the test.