Download or read book Laser induced Fluorescence Measurements of Vapor phase Polycyclic Aromatic Hydrocarbons I Evaluation of One and Two photon Excitation Processes for Mixture Analysis II Flame Temperature Measurements Using the Anomalous Fluorescence of Pyrene written by Diane LeAnna Peterson and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book American Doctoral Dissertations written by and published by . This book was released on 1987 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser Induced Fluorescence Study of the Heterogeneous Interaction of Polycyclic Aromatic Hydrocarbons with Aqueous Surfaces microform Adsorption and Reaction with Gas phase Ozone written by Baagi Thema Mmereki and published by Library and Archives Canada = Bibliothèque et Archives Canada. This book was released on 2005 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have also measured the kinetics and products of a reaction between gas-phase ozone and anthracene adsorbed at the air-aqueous interface. The reactions at the "uncoated" air-water interface and at an interface consisting of a monolayer of various organic compounds were studied. In all the cases, the reaction follows a Langmuir-Hinshelwood mechanism, in which ozone first adsorbs to the air-aqueous interface, and then reacts with adsorbed anthracene. For typical atmospheric ozone concentrations, the estimated reactive uptake coefficient ranges from 2 x 10-8 to 3 x 10-7 depending on the nature of the air-aqueous interface. Smaller (C4, C6) carboxylic acids at the interface inhibit the reaction (compared to the "clean" water surface); 1-octanol enhances it. Under some circumstances, oxidation by ozone on aqueous surfaces may be more important in the atmosphere than gas phase oxidation by OH radicals. The fate of atmospheric semi-volatile organic compounds (SOCs) such as polycyclic aromatic hydrocarbons (PAHs) depends, in part, on their distribution between the gas phase and particulate phases, and oxidation reactions. In the daytime troposphere, photochemically produced OH radicals dominate these reactions, whereas chlorine atoms may contribute to the oxidation of certain PAHs in coastal areas. In the dark, oxidation by nitrate radicals (NO3) may also be important, whereas ozone can contribute to the oxidation both during the day and at night. We have developed a laser-induced fluorescence (LIF) method to study adsorption and oxidation of PAHs at the air-aqueous interface. This method allows to directly probe the mechanisms and extent of PAH uptake on aqueous surfaces. The kinetics of the adsorption of anthracene and pyrene onto "pure" water and water coated with an organic film were measured. The surface uptake coefficients of both PAHs are estimated to be on the order of 10-5, and increase by a factor of 2--3 for uptake to the 1-octanol coated water surface. However, the surface uptake of pyrene to a hexanoic-acid-coated aqueous surface does not display this enhancement. Resolved fluorescence spectra of pyrene adsorbed onto 1-octanol-coated surfaces indicate that pyrene is in a less polar environment than when adsorbed at the hexanoic-acid-coated surfaces.

Download or read book Index to American Doctoral Dissertations written by and published by . This book was released on 1989 with total page 1252 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Strategies for Planar Laser induced Fluorescence Thermometry in Shock Tube Flows written by Ji Hyung Yoo and published by Stanford University. This book was released on 2011 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis was motivated by the need to better understand the temperature distribution in shock tube flows, especially in the near-wall flow regions. Two main ideas in planar laser-induced fluorescence (PLIF) diagnostics are explored in this thesis. The first topic is the development of a single-shot PLIF diagnostic technique for quantitative temperature distribution measurement in shock tube flow fields. PLIF is a non-intrusive, laser-based diagnostic technique capable of instantaneously imaging key flow features, such as temperature, pressure, density, and species concentration, by measuring fluorescence signal intensity from laser-excited tracer species. This study performed a comprehensive comparison of florescence tracers and excitation wavelengths to determine the optimal combination for PLIF imaging in shock tube flow applications. Excitation of toluene at 248nm wavelength was determined to be the optimal strategy due to the resulting high temperature sensitivity and fluorescence signal level, compared to other ketone and aromatic tracers at other excitation wavelengths. Sub-atmospheric toluene fluorescence yield data was measured to augment the existing photophysical data necessary for this diagnostic technique. In addition, a new imaging test section was built to allow PLIF imaging in all regions of the shock tube test section, including immediately adjacent to the side and end walls. The signal-to-noise (SNR) and spatial resolution of the PLIF images were optimized using statistical analysis. Temperature field measurements were made with the PLIF diagnostic technique across normal incident and reflected shocks in the shock tube core flow. The resulting images show uniform spatial distribution, and good agreement with conditions calculated from the normal shock jump equations. Temperature measurement uncertainty is about 3.6% at 800K. The diagnostic was also applied to image flow over a wedge. The resulting images capture all the flow features predicted by numerical simulations. The second topic is the development of a quantitative near-wall diagnostic using tracer-based PLIF imaging. Side wall thermal boundary layers and end wall thermal layers are imaged to study the temperature distribution present under constant pressure conditions. The diagnostic technique validated in the shock tube core flow region was further optimized to improve near-wall image quality. The optimization process considered various wall materials, laser sheet orientations, camera collection angles, and optical components to find the configuration that provides the best images. The resulting images have increased resolution (15[Mu]m) and are able to resolve very thin non-uniform near-wall temperature layers (down to 60[Mu]m from the surface). The temperature field and thickness measurements of near-wall shock tube flows under various shock conditions and test gases showed good agreement with boundary layer theory. To conclude this thesis, new applications and future improvements to the developed PLIF diagnostic technique are discussed. These suggested refinements can provide an even more robust and versatile PLIF imaging technique capable of measuring a wider range of flow conditions near walls.

Download or read book Tracer based Planar Laser induced Fluorescence Diagnostics written by Brian Ho-yin Cheung and published by Stanford University. This book was released on 2011 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two advances to tracer-based planar laser-induced fluorescence (PLIF) diagnostics are presented in this work. The first improvement is the development of a 3-pentanone fluorescence quantum yield (FQY) database and model for a wide range of conditions in support of quantitative PLIF diagnostics. In addition, this work presents a sensitive, time-resolved tracer-based PLIF diagnostic, accomplished by using a continuous-wave (CW) laser with the high-FQY tracer toluene. Because of its ease of use and desirable photophysical properties, PLIF diagnostics using 3-pentanone as a tracer are common, particularly for internal combustion engine (ICE) diagnostics. Thus, there is a need for 3-pentanone FQY measurements and modeling over a wide range of temperatures, pressures, and excitation wavelengths. For insight into the collisionless process in the FQY model, measurements were made in 3-pentanone vapor at low-pressures across a range of temperatures using a flowing cell. Laser excitation with 248, 266, 277, 308 nm wavelengths were utilized, and Rayleigh scattering of the laser beam was used to calibrate the optical efficiency of the collection optics and detector. This low-pressure data allows calculation of the 3-pentanone fluorescence rate and non-radiative de-excitation rate in the fluorescence model. The vibrational relaxation cascade parameter for 3-pentanone collisions was also determined. Measurements of 3-pentanone FQY were also made over a range of temperatures and pressures relevant to diagnostic applications, and, in particular, combined high-temperature and high-pressure conditions applicable to internal combustion engines (ICE). These data were collected in a custom-built optical cell capable of simultaneous high-pressure and high-temperature conditions. The behavior of the FQY in nitrogen for temperatures up to 745 K and in air up to 570 K was examined for pressures from 1 to 25 bar. These data were used to further optimize the parameters in the FQY model representing collisional processes. The large quantity of data with 308 nm excitation allowed optimization of the nitrogen quenching rate, and data in air were used to optimize the oxygen quenching rate. These data were also used to optimize the vibrational relaxation parameters for nitrogen and oxygen. The model with the updated parameters is consistent with the data collected in the current work, as well as with fluorescence measurements made in optical ICEs up to 1100 K and 28 bar. Another area of tracer-based PLIF diagnostics development is time-resolved imaging. Because PLIF diagnostics are often performed using pulsed lasers, the time resolution of measurements is limited to the pulse rate of laser. Use of a high-powered visible laser with an off-the-shelf cavity frequency doubler is shown to produce a moderate-power CW beam in the ultraviolet wavelength regime. Application of this CW source to excite toluene, a high-FQY tracer, yields a sensitive, time-resolved tracer-based PLIF diagnostic. Fluctuation detection limits for tracer mole fraction were investigated by applying the diagnostic to an atmospheric temperature and pressure nitrogen jet seeded with 4% toluene, and detection limits of better than 1% of the maximum toluene mole fraction were achieved for detection of fluorescence signal at a point, along a line, and over a plane. The diagnostic was also demonstrated on a turbulent jet for line and planar detection and demonstrated the potential for toluene time-resolved PLIF diagnostics with CW lasers.

Download or read book Measurement of Radical species Concentrations and Polycyclic Aromatic Hydrocarbons in Flames by Fluorescence and Absorption Using a Tunable Dye Laser Progress Report March 1 1980 February 28 1981 written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A theoretical and experimental investigation of OH saturated fluorescence is described. The goal of the research is to develop a saturated fluorescence technique which will yield accurate molecular number densities over a wide range of flame pressure, temperature, and composition. Experimentally, OH is excited by a ten nanosecond pulse from a Nd:YAG-pumped dye laser tuned to an isolated rotational transition in the (0,0) band of the A2.sigma.-X2 pi electronic system. The resulting fluorescence signal is resolved both spectrally and temporally. Total OH number densities are calculated by collecting fluorescence from the directly excited upper rotational level, and using the balanced cross-rate model to analyze the experimental data. Fluorescence measurements of OH number density agree to within a factor of three with the results of independent OH absorption measurements. Significantly, the ratio of the fluorescence signal to the number density measured by absorption is nearly the same in 30, 100 and 250 torr H2/O2/N2 flat flames, demonstrating the insensitivity of the saturated fluorescence signal to the quenching environment of the radical. Collisional transfer in excited OH is studied by recording the time development of OH fluorescence spectrum. The experimental spectra are compared with the results of time-dependent computer modeling. By varying rotational transfer rates until the calculated and experimental spectra agree, rotational transfer cross sections can be calculated. The signal processing system was thoroughly checked by comparing the photomultiplier output to that of a fast photodiode, and by comparing single pulse Rayleigh scattering and fluorescence traces with sampling oscilloscope traces.

Download or read book Oh Planar Laser Induced Fluorescence Measurements for the Study of High Pressure Flames written by Nasa Technical Reports Server (Ntrs) and published by BiblioGov. This book was released on 2013-07 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Planar laser induced fluorescence (PLIF) is used by the Combustion Branch at the NASA Glenn Research Center (NASA Glenn) to assess the characteristics of the flowfield produced by aircraft fuel injectors. To improve and expand the capabilities of the PLIF system new equipment was installed. The new capabilities of the modified PLIF system are assessed by collecting OH PLIF in a methane/air flame produced by a flat flame burner. Specifically, the modifications characterized are the addition of an injection seeder to a Nd: YAG laser pumping an optical parametric oscillator (OPO) and the use of a new camera with an interline CCD. OH fluorescence results using the injection seeded OPO laser are compared to results using a Nd: YAG pumped dye laser with ultraviolet extender (UVX). Best settings of the new camera for maximum detection of PLIF signal are reported for the controller gain and microchannel plate (MCP) bracket pulsing. Results are also reported from tests of the Dual Image Feature (DIF) mode of the new camera which allows image pairs to be acquired in rapid succession. This allows acquisition of a PLIF image and a background signal almost simultaneously. Saturation effects in the new camera were also investigated and are reporte

Download or read book Applications of Laser Induced Fluorescence Excitation Emission Matrix Spectroscopy for the Analysis of PAHs written by Sean J. Hart and published by . This book was released on 1998 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt: For HPLC and FIA, the data are analyzed by examining the summed fluorescence plots and qualitatively comparing the EEMs with standard measurements made with the same system. Species are qualitatively identified and quantitated by RAFA using pure component EEMs as standards and the EEMs measured during an analysis as the unknowns. RAFA calculated PAH concentrations in HPLC and FIA were in the near-quantitative regime, typically within a factor of 2 of the known concentration for laboratory-prepared mixtures. Several real world samples were analyzed and the results were generally acceptable: for HPLC all components were identified and all except two were quantitated to within a factor of 2. Analysis of lab mixtures by FIA yielded good agreement with known concentrations. The analysis of complex real world samples with many components provided reasonable qualitative identification of species and estimates of concentration.

Download or read book Oh Planar Laser Induced Fluorescence Plif Measurements for the Study of High Pressure Flames An Evaluation of a New Laser and a New Camera System written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2019-01-19 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Planar laser induced fluorescence (PLIF) is used by the Combustion Branch at the NASA Glenn Research Center (NASA Glenn) to assess the characteristics of the flowfield produced by aircraft fuel injectors. To improve and expand the capabilities of the PLIF system new equipment was installed. The new capabilities of the modified PLIF system are assessed by collecting OH PLIF in a methane/air flame produced by a flat flame burner. Specifically, the modifications characterized are the addition of an injection seeder to a Nd: YAG laser pumping an optical parametric oscillator (OPO) and the use of a new camera with an interline CCD. OH fluorescence results using the injection seeded OPO laser are compared to results using a Nd: YAG pumped dye laser with ultraviolet extender (UVX). Best settings of the new camera for maximum detection of PLIF signal are reported for the controller gain and microchannel plate (MCP) bracket pulsing. Results are also reported from tests of the Dual Image Feature (DIF) mode of the new camera which allows image pairs to be acquired in rapid succession. This allows acquisition of a PLIF image and a background signal almost simultaneously. Saturation effects in the new camera were also investigated and are reported. Tedder, Sarah and Hicks, Yolanda Glenn Research Center NASA/TM-2012-217614, E-182

Download or read book Laser Induced Fluorescence Measurements and Modeling of Nitric Oxide in Counterflow Diffusion Flames written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-27 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: The feasibility of making quantitative nonintrusive NO concentration ([NO]) measurements in nonpremixed flames has been assessed by obtaining laser-induced fluorescence (LIF) measurements of [NO] in counterflow diffusion flames at atmospheric and higher pressures. Comparisons at atmospheric pressure between laser-saturated fluorescence (LSF) and linear LIF measurements in four diluted ethane-air counterflow diffusion flames with strain rates from 5 to 48/s yielded excellent agreement from fuel-lean to moderately fuel-rich conditions, thus indicating the utility of a model-based quenching correction technique, which was then extended to higher pressures. Quantitative LIF measurements of [NO] in three diluted methane-air counterflow diffusion flames with strain rates from 5 to 35/s were compared with OPPDIF model predictions using the GRI (version 2.11) chemical kinetic mechanism. The comparisons revealed that the GRI mechanism underpredicts prompt-NO by 30-50% at atmospheric pressure. Based on these measurements, a modified reaction rate coefficient for the prompt-NO initiation reaction was proposed which causes the predictions to match experimental data. Temperature measurements using thin filament pyrometry (TFP) in conjunction with a new calibration method utilizing a near-adiabatic H2-air Hencken burner gave very good comparisons with model predictions in these counterflow diffusion flames. Quantitative LIF measurements of [NO] were also obtained in four methane-air counterflow partially-premixed flames with fuel-side equivalence ratios (phi(sub B)) of 1.45, 1.6, 1.8 and 2.0. The measurements were in excellent agreement with model predictions when accounting for radiative heat loss. Spatial separation between regions dominated by the prompt and thermal NO mechanisms was observed in the phi(sub B) = 1.45 flame. The modified rate coefficient proposed earlier for the prompt-NO initiation reaction improved agreement between code predictions and measurements in the re

Download or read book Determination and Analysis of Multi Photon Excitation E Missive Species written by Joseph B. McGee Turner and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The exploitation of ultrafast laser properties has been recently increasing. Recent research in this lab demonstrated the ability of femtosecond pulses to give two photons simultaneously, exciting the system above the first excited state. This ability enables for extended environments of excitation, the study of molecular symmetries and photochemistry otherwise unobservable at single photon absorbencies. This paper highlights two uses of the laser system, the first being determination of the spectral properties of species being synthesized and 'tuned' to be able to have a strong two photon cross section. The second use is the excitation of highly symmetrical species displaying anomalous fluorescence emission. The trends of the properties of the novel substituted enediynes gives a greater insight to the properties that enable a large two-photon cross section, and enables us to postulate species that would be ideal for a C1-C5 cyclization process to be activated by the ultrafast laser pulse. Being able to observe the polycyclic aromatic hydrocarbons in acidic environments we are able to detect and identify multiple emissive and non-emissive species.

Download or read book Comparison of In Situ Laser Induced Fluorescence LIF Measurements of Petroleum Hydrocarbons in Soils with Conventional Laboratory Measurements written by and published by . This book was released on 1995 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This presentation reports the results of a comprehensive field validation effort in which measurements from the cone penetrometer deployed LIF sensor are compared directly with results from conventional laboratory-based chemical analyses of samples collected using traditional methods. To minimize spatial and temporal variability associated with sampling, discrete samples were collected immediately after push measurements by overboring the push hole with an auger and collecting soil samples with a split spoon sampler. Secondary fluorescence measurements were made on splits of the laboratory samples to provide direct comparison with laboratory results. All discrete samples were analyzed by EPA Methods 418.1, Total Recoverable Petroleum Hydrocarbons (TRPH) and DHS Method 8015-Modified, TPH. At some sites samples were also analyzed for SVOC, EPA Method 8270, and/or an enhanced 8270 that quantifies 40 individual polynuclear aromatic hydrocarbons (PAHs).

Download or read book Laser Induced Fluorescence Measurements and Modeling of Nitric Oxide in High Pressure Premixed Flames written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-25 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser-induced fluorescence (LIF) has been applied to the quantitative measurement of nitric oxide (NO) in premixed, laminar, high-pressure flames. Their chemistry was also studied using three current kinetics schemes to determine the predictive capabilities of each mechanism with respect to NO concentrations. The flames studied were low-temperature (1600 less than T less than 1850K) C2H6/O2/N2 and C2H6/O2/N2 flames, and high temperature (2100 less than T less than 2300K) C2H6/O2/N2 flames. Laser-saturated fluorescence (LSF) was initially used to measure the NO concentrations. However, while the excitation transition was well saturated at atmospheric pressure, the fluorescence behavior was basically linear with respect to laser power at pressures above 6 atm. Measurements and calculations demonstrated that the fluorescence quenching rate variation is negligible for LIF measurements of NO at a given pressure. Therefore, linear LIF was used to perform quantitative measurements of NO concentration in these high-pressure flames. The transportability of a calibration factor from one set of flame conditions to another also was investigated by considering changes in the absorption and quenching environment for different flame conditions. The feasibility of performing LIF measurements of (NO) in turbulent flames was studied; the single-shot detection limit was determined to be 2 ppm. Reisel, John R. and Laurendeau, Normand M. Unspecified Center NASA-CR-195404, E-9248, NAS 1.26:195404 NAG3-1038; RTOP 537-02-20...

Download or read book Development of a Laser Induced Fluorescence Technique for the Analysis of Organic Air Pollutants written by Patricia B. C. Forbes and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants which are of concern due to their potential human toxicity. They are formed during numerous combustion processes, including biomass burning and diesel vehicular emissions, which are of relevance in developing countries. A novel analytical screening method for atmospheric polycyclic aromatic hydrocarbons (PAHs) was developed in this study based on laser induced fluorescence (LIF) of samples on quartz multi-channel polydimethylsiloxane (PDMS) traps. A tunable dye laser with a frequency doubling crystal provided the excitation radiation, and a double monochromator with a photomultiplier tube detected emitted fluorescence. The method allowed for the rapid (

Download or read book OH planar laser induced fluorescence PLIF measurements for the study of high pressure flames written by Sarah Tedder and published by . This book was released on 2012 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Current Programs written by and published by . This book was released on 1976 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt: