Pas de résumé en français / One of the new challenges of conservation science is the development of field instrumentation to analyze works of art. In order to get the most information on the material, it is often necessary to perform complementary analyses by juggling different analytical techniques. This time-consuming drawback involves a difficulty to analyze the artwork on the same spot of the surface. However, some of spectroscopies have in common to use the same laser as excitation source and the collection of the emitted signal could be recorded by the same spectrometer. In this spirit, the aim of this research project is the development of a hybrid system in laboratory grouping together three analytical techniques (LIBS, LIF and Raman spectroscopy) in a single instrument. The relevance for combining these three spectroscopies is to identify a material (molecular and elemental analysis) without any preliminary preparation, regardless of its organic or inorganic nature, on the surface and in depth, without any surrouding light interference thanks to time-resolution. Such instrumentation would allow to characterize different materials from cultural heritage such as copper corrosion products and wall paintings organized in stratigraphic layers which are the example of applications in this work. A complete study on LIBS-LIF-Raman hybrid was carried out from conception to instrumental achievement, as well as automatic control to data fusion processings in order to elaborate a strategy of analysis according to the material and to be able to address conservation issues.

In this present paper, the electrical characteristics of the interface between the cathode and organic layer in OLEDs are discussed. The dipole formed between the cathode and organic layer are the dominant factor resulting in the electrical characteristics of OLEDs. However, based on the Al/LiF/Alq3 architecture published by the Kodak company, it is mainly because that by inserting a LiF layer lead to change the interface characteristic of Al/Alq3 as to changed the chemical reaction occurred at the interface of Al/Alq3. The LiF interlayer could enable the contact interface being depolarized and the work function being close to the vacuum level, therefore, it will reduce the electron injection barrier to improve the OLED performance. In addition, the increase luminous efficiency was due to that without generating any gap state and interdiffusion occur at the interface of Al/LiF/Alq3. For the carrier injection model reported by several authors, the carrier injection process is summarized by two steps as follow: first, the inject carriers translate from metal Fermi level to the energy distribution of interface. Second, inject carriers translate from the energy distribution of interface to the energy distribution of organic layer, afterward, the inject carriers migrate with hopping conduction in the organic level. Hence, it will regards to the dependence of the variety of LiF thickness on the influence of the injection model, and assume that as LiF thickness is 0.5 nm the device could be able to have the best performance, and also assume that LiF was able to decompose equal number of Alq3- and the Li+ ions at the interface of Al/LiF/Alq3 contact, and that led to form a voltage in the LiF layer. Finally, we found that the simulation approaches were consistent with the experimental results very well.

Isoprene (2-methyl-1,3-butadiene) is the most abundant non-methane hydrocarbon mostly emitted from the trees and its oxidation by hydroxyl radical contributes significantly to the tropospheric ozone production. We investigate the development of a detailed predictive mechanism for isoprene oxidation using both theory and experiment. We have identified a novel cyclization pathway for the radicals formed by hydroxy radical (OH) addition to the inner carbons of isoprene. The pathway predicted that C5 carbonyl compounds are produced, and it may also provide information on the preference of sites for OH addition. The nitrite/nitrate isomerization is directly related to the competition between ozone production and radical termination and was investigated using variational RRKM theory coupled with the master equation. We find that the dominant fate of the β-hydroxy alkoxy radicals produced from the dissociation reaction of nitrite is a prompt dissociation, whereas δ-hydroxy radicals isomerize to form dihydroxy radicals. We have performed experiments using laser photolysis (LP)/ laserinduced fluorescence (LIF) spectroscopy to study the initial addition reaction of the hydroxyl radical to isoprene. The overall reaction rates were estimated from experiments conducted at various pressures and temperatures. The determined Arrhenius rates are k∞(T) = (3.49±0.46)x10-11exp(366±40)/T molecule-1 cm3 s-1 and k∞(T) = (3.58±0.18)x10- 11exp(356±18)/T molecule-1 cm3 s-1, for the OH and OD addition reactions, respectively. Isoprene oxidation in the presence of O2 and NO was studied and, based on simulations to OH cycling curves, we determined a value of (9.0±3.0)x10-12 molecule-1 cm3 s-1 for the overall reaction rate constant of hydroxy peroxy radical with NO at 298 K. We report a rate constant for O2 addition to the hydroxy alkyl radical of (2.3±2.0)x10-12 molecule-1 cm3 s-1 at 298 K. We find little generation of OH from the OD initiated oxidation of isoprene, and no significant differences in OH and OD cycling, which suggests that the H-shift isomerization is the major pathway for δ-hydroxy alkoxy radicals in agreement with theoretical predictions.

A mathematical model is developed to describe the micro/nano-scale fluid flow and heat/mass transfer phenomena in an evaporating extended meniscus, focusing on the transition film region under nonisothermal interfacial conditions. The model incorporates thermocapillary stresses at the liquid-vapor interface, a slip boundary condition on the solid wall, polarity contributions to the working fluid field, and binary mixture evaporation. The analytical results show that the adsorbed film thickness and the thin film length decrease with increasing superheat by the thermocapillary stresses, which influences detrimentally the evaporation process by degrading the wettability of the evaporating liquid film. In contrast, the slip effect and the binary mixture enhance the stability of thin film evaporation. The slip effect at the wall makes the liquid in the transition region flow with smaller flow resistance and thus the length of the transition region increases. In addition, the total evaporative heat flow rate increases due to the slip boundary condition. The mixture of pentane and decane increases the length of the thin film by counteracting the thermocapillary stress, which enhances the stability of the thin film evaporation. The polarity effect of water significantly elongates the thin film length due to the strong adhesion force of intermolecular interaction. The strong interaction force restrains the liquid from evaporation for a polar liquid compared to a non-polar liquid. In the experimental part, laser induced fluorescence (LIF) thermometry has been used to measure the microscale temperature field of a heated capillary tube with a 1 mm by 1 mm square cross section. For the temperature measurement, the calibration curve between the temperature and the fluorescent intensity ratio of Rhodamine-B and Rhodamine-110 has been successfully obtained. The fluorescent intensity ratio provides microscale spatial resolution and good temperature dependency without any possible bias error caused by illuminating light and background noise usually encountered in conventional LIF techniques. For the validation of the calibration curve obtained, thermally stratified fields established inside a glass cuvette of 10 mm width were measured. The measurement result showed a good agreement with the linear prediction. The temperature measurement in a 1 mm capillary tube could provide the feasible method of temperature measurement for the thin film region in the future.

In this study, the dependence of metal/Alq3 Schottky contact barrier on the current¡Vvoltage characteristics of organic light emitting diodes was investigated to know the charge injection mechanism of OLED with the single-layer metal/Alq3/ metal structures, and the current density increases obviously with the reduction of contact potential barrier. As the thin LiF layer is inserted between the Al electrode and the Alq3 layer, it shows that the electron injection was promoted, and higher electroluminescence efficiency was also obtained. Both the energetic barrier and the tunneling integral parameter are reduced when the LiF layer thickness increases. For very thin films of LiF, the beneficial effect of the barrier reduction is dominant. When the film grows thicker, the negative insulating effect becomes dominant. Besides of simulating the current¡Vvoltage characteristics of organic light emitting diodes (OLED) based on Alq3 in combination with different cathodes, it was simulated that the current¡Vvoltage characteristics of OLED with an inserted LiF layer between metal and organic material, and then the OLED with various thicknesses of LiF films were also simulated. Finally, the result of simulations was compared to achieve a better description for the characteristics of current¡Vvoltage for the single carrier and layer based OLED.

In this dissertation, the electrical characteristics of the interface between the metal cathode and organic layer in OLEDs are detailed investigated. Currently, surveying on the literature, it is limited in understanding the interfacial characteristics and the injection process of electron at interface, therefore the carrier injection phenomena investigated here is still based on the traditionally inorganic semiconductor physics. As a thin LiF layer inserted between the Al and Alq3 layers, the performance of OLED shown a great deal of improvement, such as lowering the driving voltage and increasing the luminescence efficiency. At first, we study how a very thin LiF layer affecting the performance of OLED device, and the feasible mechanisms attributed to this improvements. Then, the further discussion should be focused on the injection model built for the charge at metal/organic interfaces. Finally, the relationship that the injection model related to the variety of LiF layer thickness could be investigated. From the experimental data, the Al/LiF/Alq3 devices with the LiF thickness of 0.5nm have shown the best performance, and the device performance decay as the thickness of LiF layer increased over 0.5nm. In this study, it assumes that the LiF layer just forms an ¡§integrated¡¨ thin insulating film and lowing the charge injection as the layer thickness over 0.5nm, and it also assume that in model derived process is independent on the metal work function. Since the molecular structure of organic materials is quite difference from the valence band structure in inorganic semiconductor materials, it could be assumed no band bending like that the p-n junction at the interface of inorganic semiconductor under thermal equilibrium. After theoretical approach, we get the reasonable results by comparing with the literatures reported recently. The conclusion of this study reveals that the charge injection is independent on the metal work function, but is determined by the interface structure characteristic of interface structure at metal/organic interfaces. Furthermore, in the Al/LiF/Alq3 structure, the chemical reaction is saturated at the interface as the LiF layer forms a ¡§integrated¡¨ thin insulating film. Therefore, the device performance decay is the effect due to the insulating LiF layer when the thickness of LiF layer is over 0.5nm.

A ratiometric laser induced fluorescence (LIF) thermometry applied to micro-scale temperature measurement for natural convection flows. To eliminate incident light non-uniformity and imperfection of recording device, two fluorescence dyes are used: one is temperature sensitive fluorescence dye (Rhodamine B) and another is relatively temperature insensitive fluorescence dye (Rhodamine 110). Accurate and elaborate calibration for intensity ratio verses temperature obtained using an isothermal cuvette, which was controlled by two thermo-bathes. 488nm Ar-ion laser used for incident light and two filter sets used for separating each fluorescence emission. Thermally stratified filed of 10mm channel with micro-scale resolution measured within 1.3?C uncertainty of liner prediction with 23?m x 23?m spatial resolution. Natural convection flows at 10mm channel also observed. The several difficulties for applying to heated evaporating meniscus were identified and a few resolutions were suggested.

A mathematical model is developed to describe the micro/nano-scale fluid flow and heat/mass transfer phenomena in an evaporating extended meniscus, focusing on the transition film region under nonisothermal interfacial conditions. The model incorporates thermocapillary stresses at the liquid-vapor interface, a slip boundary condition on the solid wall, polarity contributions to the working fluid field, and binary mixture evaporation. The analytical results show that the adsorbed film thickness and the thin film length decrease with increasing superheat by the thermocapillary stresses, which influences detrimentally the evaporation process by degrading the wettability of the evaporating liquid film. In contrast, the slip effect and the binary mixture enhance the stability of thin film evaporation. The slip effect at the wall makes the liquid in the transition region flow with smaller flow resistance and thus the length of the transition region increases. In addition, the total evaporative heat flow rate increases due to the slip boundary condition. The mixture of pentane and decane increases the length of the thin film by counteracting the thermocapillary stress, which enhances the stability of the thin film evaporation. The polarity effect of water significantly elongates the thin film length due to the strong adhesion force of intermolecular interaction. The strong interaction force restrains the liquid from evaporation for a polar liquid compared to a non-polar liquid. In the experimental part, laser induced fluorescence (LIF) thermometry has been used to measure the microscale temperature field of a heated capillary tube with a 1 mm by 1 mm square cross section. For the temperature measurement, the calibration curve between the temperature and the fluorescent intensity ratio of Rhodamine-B and Rhodamine-110 has been successfully obtained. The fluorescent intensity ratio provides microscale spatial resolution and good temperature dependency without any possible bias error caused by illuminating light and background noise usually encountered in conventional LIF techniques. For the validation of the calibration curve obtained, thermally stratified fields established inside a glass cuvette of 10 mm width were measured. The measurement result showed a good agreement with the linear prediction. The temperature measurement in a 1 mm capillary tube could provide the feasible method of temperature measurement for the thin film region in the future.

The release of sodium during the combustion of black liquor is a significant source of fume formation in a kraft recovery boiler, affecting efficiency in a pulp and paper mill. The fume is deposited on the surface of heat exchanger tubes in the upper furnace, causing fouling and corrosion, especially to the superheaters. This thesis reports on work done to develop improved understanding of fume formation. The mechanisms of sodium release during each stage of black liquor combustion are influenced by the surface temperature. The addition of boron to the black liquor, which debottlenecks the recausticizing plant by a reduction in lime usage, also influences the characteristics of black liquor combustion, such as combustion time and swelling. Previously, no effective measurement technique has been available to quantify sodium concentration in the plume of a burning black liquor droplet with or without boron, or to record the distribution of surface temperature through the time history of a burning droplet. This thesis reports on the adaptation of two techniques for the measurement of the release of atomic sodium and the temperature history, and their application to investigate several aspects of the release of atomic sodium during combustion of black liquor in a flat flame environment. The simultaneous employment of a planar laser-induced fluorescence (PLIF) technique with an absorption technique has been adapted to allow quantitative measurement of the release of atomic sodium. The absorption technique has been employed to correct for both fluorescence trapping due to absorption and attenuation by high concentration of the atomic sodium in the plume, and for collisional quenching by the other major gas components present in the flat flame. An independent assessment was performed using kinetic calculations, based on measured total sodium that is residual in a particle obtained at different stages in the combustion process. These independent assessments were used to provide greater insight in to the release process and to cross-check. The influence of both the initial diameter of the droplet and addition of boron to the black liquor on the temporal release and the release rate of atomic sodium during the combustion have been performed using the present PLIF technique. The second technique, two-dimensional two-colour optical pyrometry, has been adapted to measure the distribution of surface temperature and the swelling (change in surface area) of a burning black liquor droplet. The influence of surface temperature or the change in the external surface area of the droplet on the release of atomic sodium during the combustion of black liquor has been assessed through concurrent use of both adapted techniques. The highest concentration of atomic sodium was measured in the final stage of combustion that of smelt coalescence, where it is an order of magnitude greater than in the other stages combined. While the extensive release of atomic sodium at high temperature in this final combustion stage occurs in only a relatively small percentage of droplets in a kraft recovery boiler, the effect could still be significant in fume formation. This is because the extensive release is expected to occur in the very small droplets, predominantly generated by splitting or physical ejection. Small droplets will have a very short combustion time and so could remain in suspension within hot gases for sufficient time for extensive release of sodium. These measurements outcomes can be used to support the future development of sub-models for computational fluid dynamics (CFD) models in order to better understand and optimise fume formation in a kraft recovery boiler. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1474431 / Thesis (Ph.D.) - University of Adelaide, School of Mechanical Engineering, 2009

The release of sodium during the combustion of black liquor is a significant source of fume formation in a kraft recovery boiler, affecting efficiency in a pulp and paper mill. The fume is deposited on the surface of heat exchanger tubes in the upper furnace, causing fouling and corrosion, especially to the superheaters. This thesis reports on work done to develop improved understanding of fume formation. The mechanisms of sodium release during each stage of black liquor combustion are influenced by the surface temperature. The addition of boron to the black liquor, which debottlenecks the recausticizing plant by a reduction in lime usage, also influences the characteristics of black liquor combustion, such as combustion time and swelling. Previously, no effective measurement technique has been available to quantify sodium concentration in the plume of a burning black liquor droplet with or without boron, or to record the distribution of surface temperature through the time history of a burning droplet. This thesis reports on the adaptation of two techniques for the measurement of the release of atomic sodium and the temperature history, and their application to investigate several aspects of the release of atomic sodium during combustion of black liquor in a flat flame environment. The simultaneous employment of a planar laser-induced fluorescence (PLIF) technique with an absorption technique has been adapted to allow quantitative measurement of the release of atomic sodium. The absorption technique has been employed to correct for both fluorescence trapping due to absorption and attenuation by high concentration of the atomic sodium in the plume, and for collisional quenching by the other major gas components present in the flat flame. An independent assessment was performed using kinetic calculations, based on measured total sodium that is residual in a particle obtained at different stages in the combustion process. These independent assessments were used to provide greater insight in to the release process and to cross-check. The influence of both the initial diameter of the droplet and addition of boron to the black liquor on the temporal release and the release rate of atomic sodium during the combustion have been performed using the present PLIF technique. The second technique, two-dimensional two-colour optical pyrometry, has been adapted to measure the distribution of surface temperature and the swelling (change in surface area) of a burning black liquor droplet. The influence of surface temperature or the change in the external surface area of the droplet on the release of atomic sodium during the combustion of black liquor has been assessed through concurrent use of both adapted techniques. The highest concentration of atomic sodium was measured in the final stage of combustion that of smelt coalescence, where it is an order of magnitude greater than in the other stages combined. While the extensive release of atomic sodium at high temperature in this final combustion stage occurs in only a relatively small percentage of droplets in a kraft recovery boiler, the effect could still be significant in fume formation. This is because the extensive release is expected to occur in the very small droplets, predominantly generated by splitting or physical ejection. Small droplets will have a very short combustion time and so could remain in suspension within hot gases for sufficient time for extensive release of sodium. These measurements outcomes can be used to support the future development of sub-models for computational fluid dynamics (CFD) models in order to better understand and optimise fume formation in a kraft recovery boiler. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1474431 / Thesis (Ph.D.) - University of Adelaide, School of Mechanical Engineering, 2009