Dissertations / Theses on the topic 'Light angular scattering spectroscopy'
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1
Hillman, Timothy R. "Microstructural information beyond the resolution limit : studies in two coherent, wide-field biomedical imaging systems." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0085.
2
Šćepanović, Obrad R. 1980. "Light scattering spectroscopy clinical imaging device implementation." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/87887.
3
Järvinen, Emma [Verfasser]. "Investigations of Angular Light Scattering by Complex Atmospheric Particles / Emma Järvinen." Karlsruhe : KIT Scientific Publishing, 2016. http://www.ksp.kit.edu.
4
Backman, Vadim 1973. "Early diagnosis of cancer using light scattering spectroscopy." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/29892.
Abstract:
Thesis (Ph. D.)--Harvard--Massachusetts Institute of Technology Division of Health Sciences and Technology, 2001.Includes bibliographical references.
This thesis presents a novel optical technique, light scattering spectroscopy (LSS), developed for quantitative characterization of tissue morphology as well as in vivo detection and diagnosis of the diseases associated with alteration of normal tissue structure such as precancerous and early cancerous transformations in various epithelia. LSS employs a wavelength dependent component of light scattered by epithelial cells to obtain information about subcellular structures, such as cell nuclei. Since nuclear atypia is one of the hallmarks of precancerous and cancerous changes in most human tissues, the technique has the potential to provide a broadly applicable means of detecting epithelial precancerous lesions and noninvasive cancers in various organs, which can be optically accessed either directly or by means of optical fibers. We have developed several types of LSS instrumentation including 1) endoscopically compatible LSS-based fiber-optic system;
(cont.) 2) LSS-based imaging instrumentation, which allows mapping quantitative parameters characterizing nuclear properties over wide, several cm2, areas of epithelial lining; and 3) scattering angle sensitive LSS instrumentation (a/LSS), which enables to study the internal structure of cells and their organelles, i.e. nuclei, on a submicron scale. Multipatient clinical studies conducted to test the diagnostic potential of LSS in five organs (esophagus, colon, bladder, cervix and oral cavity) have shown the generality and efficacy of the technique and indicated that LSS may become an important tool for early cancer detection as well as better biological understanding of the disease.
by Vadim Backman.
Ph.D.
5
Monem, A. S. M. A. "Angular light scattering from phospholipid vesicles and the effect of magnetic fields." Thesis, University of Southampton, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373565.
6
Barnett, David M. "On multiple optical scattering in a scanning nephelometer." Thesis, Boston Spa, U.K. : British Library Document Supply Centre, 2000. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.323870.
7
Thapa, Nabin K. "Characterizing Liquid-Fluid Interfaces Using Surface Light Scattering Spectroscopy." Kent State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=kent1564059703319064.
8
Kolevzon, Vladimir. "Surface Light Scattering Spectroscopy of the Gallium Liquid-Vapor Interface." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-31647.
Abstract:
Surface Light Scattering Spectroscopy of the Gallium Liquid-Vapor Interface Vladimir Kolevzon Abstract High frequency capillary waves at liquid Ga surface have been studied by means of quasielastic light scattering spectroscopy. The observed frequencies and damping constants of waves differed greatly from classical theoretical treatment of liquid Ga surface as that of a simple liquid. This effect was explained due to the presence of the surface layer, possessing visco-elastic properties extracted, for the first time, from the fit of experimental spectra with an appropriate theoretical form. Negative value of the surface dilational viscosity has been derived for all wavenumbers studied. At high wavenumbers q the wave dispersion behavior is best likely linked to the weak coupling between dilational and capillary modes, while at low and moderate q the experimental data resemble to the mixed oscillations. This behavior is consistent with an influence of diffusion and adsorption on the waves propagation.
9
Macfadyen, Allan John. "Photon correlation spectroscopy and electrophoretic light scattering using optical fibres." Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277140.
10
Lau, Condon. "Differential light scattering spectroscopy measurements for detecting and imaging cancer." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35666.
Abstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references.
Optical spectroscopy show great promise for diagnosing the earliest stages of cancer. Light scattering spectroscopy (LSS), the study of single elastic backscattering as a function of wavelength and angle, can detect subcellular structural changes in early cancer. We have developed two novel differential light scattering spectroscopy techniques, space differential LSS (SD/LSS) and b-angle differential LSS (/LSS), for detecting the single backscattering signal from a reflectance spectrum dominated by multiple scattering and diffuse reflectance. SD/LSS exploits the penetration abilities of diffuse reflectance while /LSS exploits the angular asymmetry of single backscattering from large particles. O/LSS has the added advantage of being able to isolate single backscattering specifically from scatterers much larger than the wavelength. We implement /LSS to interrogate colon tissue and to develop diagnostic algorithms based on Mie theory. The results show great promise for diagnosing cancer. Instrumentation is being developed to implement SD/LSS and /LSS together in a wide area imaging system with the goal of studying and detecting cancer at its earliest stages in vivo and in real time. The system has been validated with controlled tissue phantoms and will soon be ready for clinical studies.
by Condon Lau.
S.M.
11
Kolevzon, Vladimir. "Surface Light Scattering Spectroscopy of the Gallium Liquid-Vapor Interface." Forschungszentrum Rossendorf, 1996. https://hzdr.qucosa.de/id/qucosa%3A21991.
Abstract:
Surface Light Scattering Spectroscopy of the Gallium Liquid-Vapor Interface Vladimir Kolevzon Abstract High frequency capillary waves at liquid Ga surface have been studied by means of quasielastic light scattering spectroscopy. The observed frequencies and damping constants of waves differed greatly from classical theoretical treatment of liquid Ga surface as that of a simple liquid. This effect was explained due to the presence of the surface layer, possessing visco-elastic properties extracted, for the first time, from the fit of experimental spectra with an appropriate theoretical form. Negative value of the surface dilational viscosity has been derived for all wavenumbers studied. At high wavenumbers q the wave dispersion behavior is best likely linked to the weak coupling between dilational and capillary modes, while at low and moderate q the experimental data resemble to the mixed oscillations. This behavior is consistent with an influence of diffusion and adsorption on the waves propagation.
12
Courtney, Peter R. "Correlation techniques for application in photon correlation spectroscopy." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237235.
13
Dahlgren, Eric D. "Small angle light scattering analysis of tissue." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0111102-171921.
14
Jefferies, J. P. F. "Multipassed Fabry-Perot spectroscopy and its Fourier analysis." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375074.
15
Campbell, Dawn M. "Light scattering study of attractive interactions in a model microemulsion system /." Online version of thesis, 1992. http://hdl.handle.net/1850/10697.
16
Paladugula, Jithendar. "Parallelization of light scattering spectroscopy and its integration with computational grid environments." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0005280.
17
Bassan, Paul. "Light scattering during infrared spectroscopic measurements of biomedical samples." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/light-scattering-during-infrared-spectroscopic-measurements-of-biomedical-samples(a2a41f54-0e61-443a-bd32-faf8f65806a7).html.
Abstract:
Infrared (IR) spectroscopy has shown potential to quickly and non-destructively measure the chemical signatures of biomedical samples such as single biological cells, and tissue from biopsy. The size of a single cell (diameter ~10-50 µm) are of a similar magnitude to the mid-IR wavelengths of light (~1-10 µm) giving rise to Mie-type scattering. The result of this scattering is that chemical information is significantly distorted in the IR spectrum.Distortions in biomedical IR spectra are often observed as a broad oscillating baseline on which the absorbance spectrum is superimposed. A spectral feature commonly observed is the sharp decrease in intensity at approximately 1700 cm-1, next to the Amide I band (~1655 cm-1), which pre-2009 was called the 'dispersion artefact'. The first contributing factor towards the 'dispersion artefact' investigated was the reflection signal arising from the air to sample interface entering the collection optics during transflection experiments. This was theoretically modelled, and then experimentally verified. It was shown that IR mapping could be done using reflection mode, yielding information from the optically dense nucleus which previously caused extinction of light in transmission mode.The most important contribution to the spectral distortions was due to resonant Mie scattering (RMieS) which occurs when the scattering particle is strongly absorbing such as biomedical samples. RMieS was shown to explain both the baselines in IR spectra, and the 'dispersion artefact' and was validated using a model system of poly(methyl methacrylate) (PMMA) of varying sizes from 5 to 15 µm. Theoretical simulations and experimental data had an excellent match thus proving the theory proposed. With an understanding of the physics/mathematics of the spectral distortions, a correction algorithm was written, the RMieS extended multiplicative signal correction (RMieS-EMSC). This algorithm modelled the measured spectrum as superposition of a first guess (the reference spectrum) which was of a similar biochemical composition to the pure absorbance spectrum of the sample, and a scattering curve. The scattering curve was estimated as the linear combination of a database of a large number of scattering curves covering a range of feasible physical parameters. Simulated and measured data verified that the RMieS-EMSC increased IR spectral quality.
18
Bassi, Andrea Li. "X-ray and light scattering from nanostructured thin films." Thesis, Durham University, 2000. http://etheses.dur.ac.uk/4631/.
Abstract:
The object of this thesis is the study of nanostructured thin films using inelastic fight scattering and elastic x-ray scattering techniques. Their use in combination with other techniques is a powerful tool for the investigation of nanostructured materials. X-ray, Raman and Brillouin characterisation of cluster-assembled carbon films, promising for applications in the field of catalysis, hydrogen storage and field emission, is here presented. X-ray reflectivity (XRR) provided a measure of the density. Raman spectroscopy showed that the local bonding in these amorphous films depends on the size distribution of the clusters and that it is possible to select the cluster size in order to grow films with tailored properties. Brillouin scattering provided a characterisation at the mesoscopic scale and an estimate of the elastic constants, revealing a very soft material. XRR was employed to study density, layering and roughness of a wide range of amorphous carbon films grown with different techniques. Some films possess an internal layering due to plasma instabilities in the deposition apparatus. By comparing XRR with Electron Energy Loss Spectroscopy, a unique value for the electron "effective mass" was deduced and a general relationship between sp(^3)-content and density was found. XRR and H effusion were used to determine the hydrogen content. A study of the size-dependent melting temperature in tin nanoparticle thin films was undertaken with a combined use of X-Ray Diffraction (XRD) and light scattering. A redshift in the position of a Rayleigh peak in the temperature-dependent Brillouin measurements was shown to be related to the melting of the nanoparticles and explained by an effective medium model. XRD also provided information on the low-level of stress in the particles. Low-frequency Raman scattering was used to study the behaviour of the acoustic modes of a single particle as a function of temperature.
19
Dorrington, Glen. "Examining biological systems at a molecular level via polarised light spectroscopy and scattering turbidity." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/106536/.
Abstract:
During the course of this work the development and optimisation of the dichroism field of spectroscopic techniques regarding their application towards living biological systems has been examined. To this end we have studied the theory of light scattering, as one of the principle flaws that can prevent accurate analysis of spectral data. The fields of Rayleigh-Gans-Debye and Mie theory were investigated and implemented into a program for the calculation of scattering for various different systems. The developed program was then optimised using previously collected data regarding the scattering produced by liposomes under flow, and further data regarding the deformation of liposomes validated. A secondary feature to be addressed was the inherent complexity of cellular spectra that comprise a variety of different components. Experimental studies were therefore conducted regarding the deconvolution of several biological systems in terms of their individual chromophores, in increasing degrees of complexity. An approach in which each component was converted into a series of Gaussian curves and the contribution of sets of these Gaussians (from each component) to the overall system spectrum was developed. Since biological systems contain various components that interact with each other, such as the hypochromicity of DNA, the influence on this spectral decomposition approach was also outlined and studied. Unusual features were observed in the most complex cellular samples of red blood cells and fission yeast, regarding the linear dichroism (LD) spectra produced in the absence of flow. Further studies were conducted regarding the simpler of these systems, red blood cells, to determine the source of these spectral features. The principle component was determined to be oxy-hemoglobin, and that both cellular and protein orientation was required to produce the observed LD spectrum. Sedimentary forces were then discovered to be the signal source within the sample vessel, and the spectrum comprised of both absorbing and scattering elements. Of the latter, both typical RGD/Mie type scattering was observed in addition to resonance scattering. In addition, it was observed that alterations to the cellular geometry, due to various environmental influences such as pH and tonicity, were directly related to spectral behaviour.
20
Peetermans, Joyce Anne. "Brownian motion of macromolecules inside single intact biological cells : microscope laser light scattering spectroscopy." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15178.
21
Higgs, D. M. J. "An investigation into the measurement of particle size in concentrated dispersions by means of angular dependent light scattering." Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234795.
22
Zhang, Fan. "Theoretical examinations of optical tomography through scattering medium." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28681/.
Abstract:
Optical tomography is considered to be a non-invasive and non-ionising technique that can create a digital volumetric model of an object by reconstructing 3D images made from light transmitted and scattered through the object. It is becoming of increasing importance in the area of tissue engineering and biomedical diagnostics. The main limit of pure optical techniques is the heavy scattering of tissue, which causes a poor imaging resolution. Ultrasound modulated optical tomography (USMOT) combines optical and ultrasonic techniques to produce optical contrast at ultrasound resolution. The modulation mechanism for incoherent USMOT is considered to be a secondary effect when coherent light is used. However, it is still valuable as it offers a chance to simulate the modulation of fluorescent light. In this thesis, several models of fluorescence imaging systems are presented including incoherent USMOT, Fluorescence lifetime extraction system, full field illumination (FI) system and scanning input (SI) system. A simple incoherent USMOT model is presented which allows varying of acoustic and optical parameters to provide an optimum setup to measure the incoherent USMOT effect. Afterwards, the combination of incoherent USMOT and fluorescence imaging is applied to provide an optimized SNR of modulated fluorescent light by changing the modulation frequency. With the presence of ultrasound, a novel lifetime extraction technique is presented which provides more accurate lifetime measurements and further makes it possible to extract fluorescence lifetimes in a heavily scattering medium. A broad range of excitation and emission optical parameters of NIR fluorescence imaging system have been investigated which aims to find out the optimized imaging pairs based on the SNR and spatial resolution detected. The scanning input system turns out to be better than the full field illumination system based on the spatial resolution detected, and longer wavelengths may lead to a higher SNR but degraded spatial resolution. The spatial resolution has been taken into account in fluorophore and imaging system selection over a broad range of excitation and emission wavelength. Experimental results are shown as well as a supplement to the simulations.
23
Carlsson, Sofia. "Surface Characterization ofGram-Negative Bacteria andtheir Vesicles : Using Fourier Transform Infrared Spectroscopy andDynamic Light Scattering." Thesis, Umeå universitet, Kemiska institutionen, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-64292.
24
Addis, Matthew James. "Transitional metal trilayers and films investigated using Brillouin light scattering and the magneto-optic Kerr effect." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243210.
25
Kalashnikov, Maxim M. "Validation of angle-resolved polarized light scattering spectroscopy as a diagnostic tool for pre-cancer detection." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/49744.
Abstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2009.Vita.
Includes bibliographical references.
Light scattering spectroscopy has emerged as a valuable diagnostic tool for cancer diagnoses in the past ten years. The interaction of light with cellular structures brings out information about morphological changes accompanying malignancy at early stages. The virtue of this technique is to extract key morphological information such as size distribution of nucleus and submicron-sized particles with minimal data acquisition and model-based data analysis. This enables wide area screening and onsite analysis, critical to the clinical applications. The extracted information, however, strongly depends on the selection of the specific model of the cell/tissue scattering and on constraints from prior knowledge about the sample, leaving the validity of the information questionable. The main focus of this thesis work is to validate various models of cell/tissue scattering used in light scattering spectroscopy. Conventional intensity-based light scattering spectroscopy, which records intensity distribution at the angular plane, was set up to measure angular and wavelength distribution of scattered light in cell monolayers, cell suspensions and rat esophagus tissues for both forward and backward scattering. Morphological information was extracted from cell models such as the cell model based on Mie theory and the power-law model. At the same time, field-based microscopy was used to measure 3D refractive index distributions of single live cells and to provide intensity-based light scattering spectroscopy with a more realistic optical model of a cell.
(cont.) From the index tomogram, the contribution of individual organelles and cellular components to the light scattering was determined without the need for modeling. Indeed, field-based microscopy was used as a validation tool for the various models and assumptions used in the intensity-based approach. Two types of scattering behavior had been previously reported for a visible range of wavelengths and an angular range of forward-to-backscattering in cells and tissues: an oscillatory behavior of scattering intensity in angle near exact forward and exact backward scatterings associated with cell body or nuclei, and smooth power-like behavior in wavelength for all scattering angles except near forward scattering. This study addresses two key questions related to the two types of behavior mentioned above: feasibility of extracting nuclear size distribution from oscillatory behavior, and extracting cellular parameter(s) characterizing smooth power law decay. To answer the first question, we performed a light scattering study with a single cell using field-based microscopy. Relative contributions to forward scattering of the cell border, the nucleus and other sub-cellular structures were established for the HT29 cell. Nuclear scattering is found to be small compared to the cell border scattering and sensitive to scattering by other sub-cellular structures. In agreement with single cell results, the cell border signal dominates forward scattering in cell suspensions of HeLa cells. This was confirmed by modeling with Mie theory and by index-matching the cell-media interface.
(cont.) Cell border signal was not observed in backscattering from cell suspensions, even with the use of large particle signal enhancement methods. Thus, the nuclear signal is estimated to be a few orders of magnitude below the current system sensitivity level and mixed with other scatterers' signals. The main scattering feature is a smooth power law in scattering wavelength. The exponent characterizing smooth power law decay, can separate normal and pre-cancerous tissues within the same tissue type, such as rat esophagus tissue. The range of power law exponents observed in the rat tissue experiments overlaps with the range of power law exponents extracted from HeLa, HT29 and T84 monolayers. Therefore, the power law exponent does not have enough dynamic range to separate independent samples with quite different morphology. In conjunction with the last statement, the power law behavior is explained by three different morphological base sets: the Mie model, describing cell as a collection of spheres, the Fourier model, in which cell is described as combination of periodic structures with a continuous range of spatial frequencies, and a fractal model, in which index fluctuations inside the cell are described by von Karman correlation function. Although all three models can explain the power law behavior, the Fourier model is the most feasible one, because, unlike the other models, no assumptions are made about structure of the sample.
by Maxim M. Kalashnikov.
Ph.D.
26
Milli, J., A. Vigan, D. Mouillet, A. M. Lagrange, J. C. Augereau, C. Pinte, D. Mawet, et al. "Near-infrared scattered light properties of the HR 4796 A dust ring." EDP SCIENCES S A, 2017. http://hdl.handle.net/10150/623201.
Abstract:
Context. HR4796A is surrounded by a debris disc, observed in scattered light as an inclined ring with a high surface brightness. Past observations have raised several questions. First, a strong brightness asymmetry detected in polarised reflected light has recently challenged our understanding of scattering by the dust particles in this system. Secondly, the morphology of the ring strongly suggests the presence of planets, although no planets have been detected to date. Aims. We aim here at measuring with high accuracy the morphology and photometry of the ring in scattered light, in order to derive the phase function of the dust and constrain its near-infrared spectral properties. We also want to constrain the presence of planets and set improved constraints on the origin of the observed ring morphology. Methods. We obtained high-angular resolution coronagraphic images of the circumstellar environment around HR4796A with VLT/SPHERE during the commissioning of the instrument in May 2014 and during guaranteed-time observations in February 2015. The observations reveal for the first time the entire ring of dust, including the semi-minor axis that was previously hidden either behind the coronagraphic spot or in the speckle noise. Results. We determine empirically the scattering phase function of the dust in the H band from 13.6 degrees to 166.6 degrees. It shows a prominent peak of forward scattering, never detected before, for scattering angles below 30 degrees. We analyse the reflectance spectra of the disc from the 0.95 mu m to 1.6 mu m, confirming the red colour of the dust, and derive detection limits on the presence of planetary mass objects. Conclusions. We confirm which side of the disc is inclined towards the Earth. The analysis of the phase function, especially below 45 degrees, suggests that the dust population is dominated by particles much larger than the observation wavelength, of about 20 mu m. Compact Mie grains of this size are incompatible with the spectral energy distribution of the disc, however the observed rise in scattering efficiency beyond 50 degrees points towards aggregates which could reconcile both observables. We do not detect companions orbiting the star, but our high-contrast observations provide the most stringent constraints yet on the presence of planets responsible for the morphology of the dust.
27
Lewis, Kristin A. "Development of a dual-wavelength photoacoustic instrument for measurement of light absorption and scattering by aerosol and gases." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3258842.
28
Chang, Yuan-Pin. "Novel probes of angular momentum polarization." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:d3880edf-436a-415e-8a74-6b1c0fd26e65.
Abstract:
New dynamical applications of quantum beat spectroscopy (QBS) to molecular dynamics are employed to probe the angular momentum polarization effects in photodissociation and molecular collisions. The magnitude and the dynamical behaviour of angular momentum alignment and orientation, two types of polarization, can be measured via QBS technique on a shot-by-shot basis. The first part of this thesis describes the experimental studies of collisional angular momentum depolarization for the electronically excited state radicals in the presence of the collider partners. Depolarization accompanies both inelastic collisions, giving rise to rotational energy transfer (RET), and elastic collisions. Experimental results also have a fairly good agreement with the results of quasi-classical trajectory scattering calculations. Chapter 1 provides the brief theories about the application of the QBS technique and collisional depolarization. Chapter 2 describes the method and instrumentation employed in the experiments of this work. In Chapter 3, the QBS technique is used to measure the total elastic plus elastic depolarization rate constants under thermal conditions for NO(A,v=0) in the presence of He, Ar, N2, and O2. In the case of NO(A) with Ar, and particularly with He, collisional depolarization is significantly smaller than RET, reflecting the weak long-range forces in these systems. In the case of NO(A)+N2/O2, collisional depolarization and RET are comparable, reflecting the relatively strong long-range forces in these systems. In Chapter 4, the QBS technique is used to measure the elastic and inelastic depolarization and total RET rate constants for OH(A,v=0) under thermal conditions in the presence of He and Ar, as well as the total depolarization rate constants under superthermal conditions. In the case of OH(A)+He, elastic depolarization is sensitive to the N rotational state, and inelastic depolarization is strongly dependent on the collision energy. In the case of OH(A)+Ar, elastic depolarization is insensitive to N, and inelastic depolarization is less sensitive to the collision energy, reflecting that the relatively strong long-range force in OH(A)+Ar system. The second part of this thesis describes the experimental studies of photodissociation under thermal conditions. Chapter 5 provides a brief introduction about several polarization parameter formalisms used for photodissociation, and the incorporation of the QBS technique to measure these polarization parameters. In this thesis, most polarization parameters of the molecular photofragments are measured using the LIF method, and the QBS technique is used as a complementary tool to probe these polarization parameters. In Chapter 6, rotational orientation in the OH(X,v=0) photofragments from H2O2 photodissociation using circularly polarized light at 193 nm is observed. Although H2O2 can be excited to both the A and B electronic states by 193 nm, the observed orientation is only related to the A state dynamics. A proposed mechanism about the coupling between a polarized photon and the H2O2 parent rotation is simulated, and the good agreement between the experimental and simulation results further confirms the validity of this mechanism. In Chapter 7, rotational orientation in the NO(X,v) photofragments from NO2 photodissociation using circularly polarized light at 306 nm (v=0,1,2) and at 355 nm (v=0,1) is observed. Two possible mechanisms, the parent molecular rotation and the coherent effect between multiple electronic states, are discussed. NOCl is photodissociated using circularly polarized light at 306 nm, and NO(X,v) rotational distributions (v=0,1) and rotational orientation (v=0) are measured. For the case of NOCl, the generation of orientation is attributed to the coherent effect.
29
Tarcea, Nicolae [Verfasser], and Jürgen [Akademischer Betreuer] Popp. "Light as a universal tool : Microcapsule sizing by elastic light scattering and mineral investigation by in situ Raman spectroscopy / Nicolae Tarcea. Betreuer: Jürgen Popp." Würzburg : Universität Würzburg, 2004. http://d-nb.info/1099791316/34.
30
Plaster, Bradley R. (Bradley Robert) 1976. "Dynamic light scattering and diffusing wave spectroscopy studies of the microscopic dynamics of polystyrene latex spheres suspened in glycerol." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/36673.
Abstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 1999.Includes bibliographical references (leaf 50).
The dynamics of polystyrene latex spheres [650 A radius] suspended in glycerol have been studied using the techniques of dynamic light scattering in the single scattering limit and diffusing wave spectroscopy in the multiple scattering regime using a charge coupled device [CCD] camera as our detector. Our experiments, which investigated suspensions of various concentrations [0.001by Bradley R. Plaster.
S.B.
31
Flückiger, Leonie [Verfasser], Thomas [Akademischer Betreuer] Möller, and Tim [Akademischer Betreuer] Laarmann. "Dynamics of single clusters in intense light pulses studied with ion spectroscopy and light scattering / Leonie Flückiger. Betreuer: Thomas Möller. Gutachter: Thomas Möller ; Tim Laarmann." Berlin : Technische Universität Berlin, 2015. http://d-nb.info/1077818696/34.
32
Montgomery, Patrick D. "MAGNETO-OPTICAL PROPERTIES OF THIN PERMALLOY FILMS: A STUDY OF THE MAGNETO-OPTICAL GENERATION OF LIGHT CARRYING ANGULAR MOMENTUM." UKnowledge, 2018. https://uknowledge.uky.edu/ece_etds/126.
Abstract:
Magneto-optical materials such as permalloy can be used to create artificial spin- ice (ASI) lattices with antiferromagnetic ordering. Magneto-optical materials used to create diffraction lattices are known to exhibit magnetic scattering at the half- order Bragg peak while in the ground state. The significant drawbacks of studying the magneto-optical generation of OAM using x-rays are cost, time, and access to proper equipment. In this work, it is shown that the possibility of studying OAM and magneto-optical materials in the spectrum of visible light at or around 2 eV is viable. Using spectroscopic ellipsometry it is possible to detect a change in the magnetization of thin permalloy films with thicknesses between 5 and 20 nm. Patterns consistent with OAM were found at 1.95 eV using a square lattice with a 4𝜋 radial phase shift in the antiferromagnetic ground state. Evidence of magnetic scattering at the half-order Bragg peak using 1.95 eV was also found.
33
Liukaityte, Simona. "Nouvelle métrologie large bande à grande dynamique pour la mesure des flux transmis, réfléchis et diffusés par des filtres optiques à hautes performances." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4351.
Abstract:
De nombreux efforts fournis sur l’avancement de la technologie de dépôt afin de répondre au besoin des utilisateurs des filtres interférentiels ont donné la naissance à la nouvelle génération des composants optiques. Les progrès techniques permettent de fabriquer les filtres avec la structure particulièrement complexe et atteindre les performances spectrales remarquables, mais aussi soulèvent de nouveaux problèmes au niveau de la diffusion. Les indicatrices de diffusion de ces filtres présentent les variations extrêmement rapides en fonction de l’angle de reprise et de la longueur d’onde, ce qui amoindrit sérieusement les performances des composants. Il est donc d’essentiel d’être capable de caractériser la diffusion lumineuse angulairement et spectralement résolue. L’objectif de cette thèse a alors été de développer l’outil expérimental, déduit pour la métrologie fine de la réponse spectrale et de la diffusion lumineuse. Le travail réalisé a donné naissance au banc SALSA (pour Spectral and Angular Light Scattering characterization Apparatus), un nouveau diffusomètre spectralement et angulairement résolu. Grâce au banc SALSA nous pouvons effectuer les mesures de diffusion sur large gamme spectrale [400 nm -1000 nm] avec la dynamique de 8 décades et la précision meilleure que 1%. Par ailleurs, le banc peut être utilisé pour la mesure de la transmission avec la dynamique de 12 décades, ce qui est performance unique sur l’échèle mondialeDue to market demand and technical progresses, a new generation of optical components requires much more sophisticated structures with a great number of layers. These complex structures enable to achieve severe optical performances but, at the same time, enhance light scattering processes. For these reasons, it is essential to develop a metrological tool which provides an accurate quantification of the spectral and angular behavior of scattering losses, with sufficient angular and spectral resolution. In order to face this issue, new investigations were performed during this PhD thesis and led to the development of the new scatterometer SALSA (Spectral and Angular Light Scattering characterization Apparatus). The use of both a broad-band source and a tunable filter allows to accurately select the illumination wavelength and the spectral bandwidth on the whole spectral range of CCD detectivity. Set-up SALSA allows us to perform the measurements of scattering losses on a wide spectral range (400-1000 nm), with high dynamics (>8 decades), high accuracy and low detectivity (a few 10-8 sr-1). Moreover, with set-up SALSA we are able to measure the transmission of interferential filters on the same spectral range, with high accuracy (1%) and a high dynamic (>10 decades, which is a unique performance)
34
Castorano, Nicholas Joseph. "The Structure and Dynamics of Diacetylene-Lipid Langmuir Monolayers." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1279558411.
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Cheng, Juan. "Light scattering study on phase transition and micro-heterogeneity in relaxor ferroelectrics (1-x)Pb(Mg₁/₃Nb₂/₃)O₃-xPbTiO₃ and (1-x)Pb(Zn₁/₃Nb2₂/₃)O₃-xPbTiO₃ /." access full-text access abstract and table of contents, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-ap-b23749179f.pdf.
Abstract:
Thesis (Ph.D.)--City University of Hong Kong, 2009."Submitted to Department of Physics and Material Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy." Includes bibliographical references (leaves 140-167)
36
Kätzel, Uwe. "Dynamic Light Scattering for the Characterization of Polydisperse Fractal Systems by the Example of Pyrogenic Silica." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1197634640783-66357.
Abstract:
Dynamic light scattering (DLS) is a method to size submicron particles by measuring their thermal motion (diffusion) in suspensions and emulsions. However, the validity of the Stokes-Einstein equation that relates the diffusion coefficient and the particle size is limited to spherical particles and very low concentrations. Within this thesis, DLS is used for the characterization of suspensions of pyrogenic silica which consists of fractal-like aggregates composed of sintered spherical primary particles. These structural features clearly complicate the understanding of DLS experiments and have been a severe obstacle to employing DLS as routine standard tool for the characterization of pyrogenic silica. The main objective of this thesis is therefore to evaluate the application of DLS in product development and quality assurance of pyrogenic silica industry, what essentially means to identify those structural properties of fractal aggregates which are measurable with DLS and to quantify the method’s sensitivity to changes in these properties. The investigations presented here are split up into four parts, simulations that establish a relation between structural and hydrodynamic properties, experiments validating the simulation results, the characterization of concentrated suspensions and the application-oriented analysis of DLS data for specific industrially relevant measurement tasksDie Dynamische Lichtstreuung (DLS) ist eine Messmethode zur Größenbestimmung submikroner Partikel. Dabei wird primär die stochastische Bewegung der Teilchen (Diffusion) in Suspensionen und Emulsionen bewertet. Die Stokes-Einstein Gleichung, die das Verhältnis zwischen gemessenem Diffusionskoeffizienten und Partikelgröße wiedergibt, ist jedoch nur für kugelförmige Teilchen, die in sehr niedriger Konzentration vorliegen, gültig. In der vorliegenden Arbeit wird die dynamische Lichtstreuung zur Charakterisierung von Suspensionen pyrogener Kieselsäure eingesetzt. Diese besteht aus fraktalen Aggregaten, die wiederum aus versinterten aber meist kugelförmigen Primärpartikeln zusammengesetzt sind. Diese strukturellen Eigenschaften erschweren die Anwendbarkeit der DLS bzw. die Interpretation der Messergebnisse und verhinderten bisher den Einsatz der DLS als Routinemethode zur Charakterisierung pyrogener Kieselsäuren. Das Hauptziel dieser Arbeit ist daher eine Bewertung der Möglichkeiten der DLS für die Produktentwicklung und Qualitätssicherung in der Herstellung pyrogener Kieselsäuren. Das bedeutet im Besonderen, dass sowohl die messbaren granulometrischen Eigenschaften als auch die Sensitivität der Methode bei Eigenschaftsänderungen ermittelt werden müssen. Die hier durchgeführten Arbeiten sind in vier Teile gegliedert: Simulationen, die eine Beziehung zwischen strukturellen und hydrodynamischen Eigenschaften herstellen, Experimente zur Validierung der Simulationsergebnisse, die Charakterisierung konzentrierter Suspensionen und die anwendungsorientierte Auswertung von DLS-Daten für spezifische industrierelevante Messaufgaben
37
Hartschuh, Ryan D. "Optical Spectroscopy of Nanostructured Materials." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1195016254.
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Townsend, Peter Stephen Morris. "Diffusion of light adsorbates on transition metal surfaces." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274001.
Abstract:
Helium-3 surface spin echo spectroscopy (HeSE) has been used to measure the diffusive dynamics of adsorbates on close-packed metal surfaces, namely hydrogen on Cu(111), Pd(111) and Ru(0001), carbon and oxygen on Ru(0001), and oxygen on Cu(111). Chapter 2 reviews the HeSE technique and describes the relevant dynamical models and statistical methods used to interpret data in later chapters. The performance of the ionizing detector is analysed, with a focus on the signal-to-noise ratio. In Chapter 3 expressions for the classical intermediate scattering function (ISF) are introduced for open and closed systems. The effects of corrugation and surface-perpendicular motion on the amplitude of different components in the ISF are modelled analytically and compared with simulation. The exact ISF for a particle on a flat surface, obeying the Generalized Langevin Equation with exponential memory friction, is calculated analytically. In Chapter 4 the analytical ISF is calculated for quantum Brownian motion and for coherent tunneling dynamics in a tight binding system. The bounce method for calculating quantum mechanical hopping rates in dissipative systems is applied to model diffusion of hydrogen on Ru(0001). Chapter 5 presents the first HeSE measurements of carbon and oxygen diffusion. C/Ru(0001) diffusion is assigned to a small carbon cluster. The jump rate has an activation energy $E_{A}=292\pm7\,$meV in the temperature range $550\,\textrm{K}\leq T \leq 1300\,$K. Oxygen diffusion is significantly slower. By comparison of literature data with the new HeSE results, the activation energy for oxygen diffusion at low coverage is estimated as $650\pm10$meV. Oxygen measurements at high coverage $\theta\approx0.22\,$ML are consistent with strong mutual O-O interactions. Surface diffusion is also observed after exposing Cu(111) to oxygen. Chapter 6 presents low-coverage measurements of protium (H) and deuterium (D) diffusion on Ru(0001), Pd(111) and Cu(111). In the quantum activated regime there is evidence for multiple jumps in all three systems, suggesting a low dynamical friction. The measurements on Ru(0001) indicate that the deep tunneling rate is much slower for D than for H.
39
Pardaev, Shokir A. "LIGHT SCATTERING STUDIES OF DEFECTS IN NEMATIC/TWIST-BEND LIQUID CRYSTALS AND LAYER FLUCTUATIONS IN FREE-STANDING SMECTIC MEMBRANES." Kent State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=kent1497022792130101.
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Nonoyama, Akihisa. "Using Multiwavelength UV-Visible Spectroscopy for the Characterization of Red Blood Cells: An Investigation of Hypochromism." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000508.
41
Pilgrová, Tereza. "Vliv podmínek přípravy na solubilizační vlastnosti a stabilitu komplexů biopolymer-tenzid." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2012. http://www.nusl.cz/ntk/nusl-216814.
Abstract:
Influence of the preparing of a biopolymer-surfactant system on its solubilization properties and stability was investigated by using fluorescence spectroscopy and dynamic light scattering methods. Investigation was made on complex of native hyaluronan with cationic surfactant cetyltrimethylammonium bromide (CTAB). System has been studied in aqueous and in saline solutions. The effect of temperature of stock solutions and freezing effect on subsequent properties were investigated. Further was examinated, what effect has a way of introducing fluorescent probe into the system on subsequent solubilization properties. It was found that the conditions of preparing of biopolymer-surfactant system have a significant effect on the solubilization properies and stability of complex.
42
Sharifian, Gh Mohammad. "Adsorption and Transport of Drug-Like Molecules at the Membrane of Living Cells Studied by Time-Resolved Second-Harmonic Light Scattering." Diss., Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/524558.
Abstract:
ChemistryPh.D.
Understanding molecular interactions at the surfaces of cellular membranes, including adsorption and transport, is of fundamental importance in both biological and pharmaceutical studies. At present, particularly with respect to small and medium size (drug-like) molecules, it is desirable to gain an understanding of the mechanisms that govern membrane adsorption and transport. To characterize drug-membrane interactions and mechanisms governing the process of molecular uptake at cellular membranes in living organisms, we need to develop effective experimental techniques to reach quantitative and time-resolved analysis of molecules at the membrane surfaces. Also, we preferably want to develop label-free optical techniques suited for single-cell and live cell analysis. Here, I discuss the nonlinear optical technique, second-harmonic light scattering (SHS), for studying molecule-membrane interactions and transport of molecules at the membrane of living cells with real-time resolution and membrane surface-specificity. Time-resolved SHS can quantify adsorption and transport of molecules, with specific nonlinear optical properties, at living organisms without imposing any mechanical stress onto the membrane. This label-free and surface-sensitive technique can even differentiate molecular transport at individual membranes within a multi-membrane cell (e.g., bacteria). In this dissertation, I present our current research and accomplishments in extending the capabilities of the SHS technique to study molecular uptake kinetics at the membranes of living cells, to monitor bacteria membrane integrity, to characterize the antibacterial mechanism-of-action of antibiotic compounds, to update the molecular mechanism of the Gram-stain protocol, to pixel-wise mapping of the membrane viscosity of the living cells, and to probe drug-induced activation of bacterial mechanosensitive channels in vitro.
Temple University--Theses
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Dunkhorst, Kirsten. "Diffusionsmessungen an Polyethylenglykolen mittels PFG-NMR-Spektroskopie und dynamischer Lichtstreuung / Diffusion measurements of poly(etylene glycol) in solution by Pulsed Field Gradient NMR spectroscopy and Dynamic Light Scattering." Gerhard-Mercator-Universitaet Duisburg, 2005. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-05052005-170324/.
Abstract:
The Pulsed Field Gradient (PFG) NMR spectroscopy was uesd to determine, via the diffusion coefficient, the molecular weights and the molecular weight distributions for sampels of poly(etylene glycol) (PEG) in D2O. Additional it was investigated, whether the components of mixtures of poly(ethylene glycol) with different molecular weights could be quantitatively determined by the differences in diffusion coefficient. The results of this study are compared with the result of the Dynamic Light Scattering (DLS) technique, the standard methode for the determination of molecular weights. The PFG NMR findings shows that the the molecular weights and the molecular weight distributions agreed well with values provided by the manufacturer. The mixtures could not be determined quantitativley, because of considerable overlaps in the molecular weight distributions. But it could be shown that the PFG NMR spectroscopy and the DLS technique complement one another.
44
Nilsson, Annica M. "Daylighting Systems : Development of Techniques for Optical Characterization and Performance Evaluation." Doctoral thesis, Uppsala universitet, Fasta tillståndets fysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-183307.
Abstract:
Successful integration of daylighting systems requires the ability to predict their performance for given climates. In this dissertation, a bottom-up approach is applied to evaluate the optical performance of a selection of daylighting systems. The evaluations are based on the optical properties of the included materials, and part of the dissertation focuses on developing new optical characterization methods. The work on characterization techniques uses an integrating sphere method to characterize the transmittance of light scattering samples more accurately. The method's principle is to reduce the discrepancy in light distribution between the reference and the sample scans by using an entry port beam diffuser. For samples exhibiting distinct light scattering patterns, the benefits of improved uniformity outweigh the errors introduced by the diffusing material. The method is applicable to any integrating sphere instrument, and its simplicity makes it suitable for standard measurements. In addition to normal-hemispherical properties, many daylighting applications require knowledge of the system's spatial light distribution. This dissertation presents a method combining experimental techniques and ray tracing simulations to assess the light distribution from a Venetian blind system. The method indicates that ray tracing based on simplified optical data is inadequate to predict the light distribution for slat materials exhibiting both specular and diffuse properties. Ray tracing is a promising complement to experimental methods used to characterize light guiding or light redirecting systems. Here, spectrophotometric measurements of a scaled mirror light pipe validate a ray tracing model. The model shows excellent agreement with experimental results for both direct and diffuse incident light. The spectral evaluation shows no dramatic color changes for the transmitted light. The ray tracing model is used to evaluate four daylighting systems for a selection of Swedish locations. The percentage of occupied time when the studied systems achieve full design illuminance is relatively low, but the systems provide a valuable contribution to the required illuminance. Additionally, this dissertation provides an overview of available energy efficient windows and illustrates the importance of including the solar energy transmittance when evaluating window energy performance. Overall, this dissertation presents optical characterization techniques for improved performance evaluations of daylighting systems.
45
Moro, Carlo Frederico. "Comportamento do peptídeo entomotóxico jaburetox-2Ec em solução e a sua interação com lipossomas miméticos de plaquetas humanas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/28438.
Abstract:
No presente trabalho, o peptídeo inseticida recombinante Jaburetox-2Ec, derivado da urease de Canavalia ensiformis (Jack bean) foi estudado, principalmente através de técnicas de espectroscopia de espalhamento de luz e raios-X. Foi analisada a tendência do peptídeo a se agregar em diferentes condições físico-químicas quando em solução aquosa, e a sua interação com membranas de lipossomas miméticos de plaquetas humanas. A partir dos dados de raio hidrodinâmico, raio de giro, e massa molar ponderal média obtidos do peptídeo em solução, foi possível observar uma tendência para maior agregação numa faixa em torno de pH 5,5, bem como ausência de agregação em pH inferior a 4,0 e superior a 7,0. Não se verificou nenhum efeito visível no nível de agregação com a adição de agente redutor ou íons, sendo que a exposição ao oxigênio do ar levou a um aumento da mesma. Os estudos de interação do Jaburetox-2Ec com lipossomas revelaram uma significante mudança estrutural na membrana, que se mostrou mais intensa com uma maior concentração do peptídeo. Foram, através de software, feitos ajustes teóricos das curvas de espalhamento de raios-X à baixos ângulos dos lipossomas, a fim de quantificar as mudanças nos parâmetros físicos das membranas causados pela ação do peptídeo. A formação de poros na membrana pelo peptídeo foi proposta como explicação para os resultados encontrados.In the present work, the insecticide recombinant peptide Jaburetox-2Ec, derived from Canavalia ensiformis (Jack bean) urease, was studied, primarily by light and X-ray scattering techniques. Its tendency to aggregate in aqueous solution under different physical-chemical conditions, and its interaction with human platelet mimetic liposome membranes were analyzed. From the data relative to hydrodynamic radii, radii of gyration and mean molecular weight obtained from the peptide in aqueous solution, it was possible to observe a tendency for greater aggregation around pH 5.5, as well as an absence of aggregation at values of pH below 4.0 and above 7.0. No visible effect on the level of aggregation was verified with the addition of reducing agent or ions, whereas the exposure to oxygen in the air resulted in an increase in this level. The studies of Jaburetox-2Ec interaction with liposomes revealed a significant structural change in the membrane, which was shown to be more intense in higher peptide concentrations. Software-assisted theoretical fits were made for the experimental small-angle X-ray scattering curves aiming to quantify the changes in the physical parameters of the membranes caused by peptide action. The formation of pores in the membrane was proposed as an explanation to the results found.
46
Lehocká, Nikola. "Agregace hyaluronanu substituovaného palmitoylem." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2018. http://www.nusl.cz/ntk/nusl-376858.
Abstract:
This thesis deals with the aggregation behaviour of palmitoylhyaluronan in two degrees of substitution, namely 10 % and 16 %. Using a fluorescence spectroscopy method with pyrene as a fluorescence probe, we found a critical micellar concentration. The results were confirmed by measuring the dynamic light scattering, which also showed an increase in the size of aggre-gates with an increasing concentration. System stability is reduced by increased ionic strength as evidenced by zeta potential measurement. Experiments found that 16 % substitution sample can form a gel. The gel is very stiff and has excellent properties, which was confirmed by rhe-ology. We also managed to incorporate pyrene in the gel, which was demonstrated by the presence of highly solvated domains that could be polymer micelles. Based on these results, 16% substitution sample was subjected the MTT assay to cytotoxicity. The results confirmed that the examined sample was not toxic.
47
Lepíková, Jana. "Studium vztahu mezi strukturou a reologickými vlastnostmi hydrogelů na makroskopické i mikroskopické úrovni." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2016. http://www.nusl.cz/ntk/nusl-240575.
Abstract:
Diploma thesis main goal is to obtain new pieces of knowledge about relationship between hydrogel structures and its flow and transport properties. Thesis is mainly focusing on combining pertinent biopolymers into model hydrogels based on agarose. Then perform correlation of results obtained by diffusion methods, and by rheologic measurements on macroscopic and microscopic level. Properties of hydrogels were measured by selected rheologic measurements, dynamic light scattering method, and correlative fluorescence spectroscopy. From these methods various parameters (MSD modules, values of complex viscosity) were obtained. Afterwards transport properties of prepared hydrogels were studied by observing Rhodamine 6G diffusion. Here two different approaches were used. From macroscopic perspective, simple principles of mass diffusion from dye solution to cuvettes filled with hydrogels containing individual biopolymers were used. From microscopic perspective, dye was added during the sample preparation and then the mass diffusion was investigated using FCS. Based on evaluated results it was discovered that added biopolymers don’t influence properties of carrier medium, in this case agarose hydrogels. During the study of prepared hydrogels’ reactivity and barrier properties some differences were observed. Charge of biopolymer and its charge density were discovered as main factors influencing transport of charged solutes into prepared hydrogels.
48
Dialetachi, Eva Lemmi Giovanini. "Espalhamento dinâmico de luz em sistemas coloidais diluídos." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-20092017-160805/.
Abstract:
A técnica de Espalhamento Dinâmico de Luz (do inglês Dynamic Light Scattering, ou DLS), também conhecida por técnica de Espectroscopia por Correlação de Fótons (do inglês Photon Correlation Spectroscopy, ou PCS), é amplamente utilizada na caraterização estrutural de sistemas coloidais, fornecendo informações importantes sobre tamanhos ca- ractersticos, tempos de correlação e efeitos de polarização no sistema. A facilidade de execução dos experimentos e praticidade das análises é uma das principais vantagens desta técnica. Especificamente para sistemas diludos compostos por partculas em solução, ela pode fornecer informações diretas sobre o raio hidrodinâmico das partculas do meio. No entanto, a obtenção desse parâmetro requer a utilização de métodos de ajuste e análise dos dados experimentais que assumem diversas caractersticas do sistema e possuem li- mitações intrnsecas devido à própria resolução do método frente presença de partculas de variados tamanhos e concentrações, polidispersões contnuas de tamanho, entre vários outros fatores. Existem casos, por exemplo, onde o mesmo conjunto experimental pode ser descrito por dois modelos diferentes. Neste projeto, é proposto um estudo sistemático das limitações dos métodos de análise frente a dados simulados e experimentais, de modo a permitir a aplicabilidade destes métodos a vários tipos de sistemas. Serão investigados casos de sistemas monodispersos e polidispersos, monomodais e multimodais, através da geração de dados simulados que mimetizem a presença desses grupos de partculas, em di- ferentes proporções e polidispersões. Como resultado, teremos indicações da precisão com que estes métodos de modelagem conseguem reproduzir os valores inseridos na simulação. Além disso, experimentos reais serão realizados utilizando amostras padrão de modo a aplicar os métodos de análise a estes dados bem como contrapor os resultados obtidos pelas simulações e pelos dados experimentais.The Dynamic Light Scattering technique, also known as Photon Correlation Spectros- copy, is widely used for the structural characterization for colloidal systems, providing important information on characteristic length scales, correlation times and polarization effects. The relative simple experimental setup and easy-to-use modeling methods are one of the main advantages of this technique. Specifically for diluted systems of particles in solution, one can obtain direct information on the hydrodynamic for the particles in the system. However, in order to retrieve this parameter it is necessary to use modeling and analysis methods for the experimental methods which assumes intrinsic characteristics on the system and have intrinsic limitations due to the resolution of the method when particles with several sizes, concentrations, etc. In several cases, the same experimental data can be described by several different models. In this project it is proposed a systematic study on the limitations on the analysis methods upon simulated and experimental data in order to investigate the applicability of these methods for several system types. Monodisperse and polydisperse systems are investigated, either composed by one type of particles (monomo- dal) or several types of particles (multimodal). As a result, one can obtain indications on the accuracy that the modeling methods can reproduce the simulated parameters. Finally, real experiments were performed using standard samples in order to test the modeling methods and to calibrate the simulation procedures.
49
Bouloussa-Huynh, Hedi. "Spectroscopie Brillouin dans les couches minces, multicouches et nanostructures magnétiques : étude de l’interaction Dzyaloshinskii-Moriya." Thesis, Paris 13, 2019. http://www.theses.fr/2019PA131025.
Abstract:
Ce travail vise à étudier, expérimentalement et théoriquement, le comportement des ondes de spin dans des couches ultraminces, multicouches et nanostructures magnétiques en présence de l’interaction Dzyaloshinskii-Moriya d’interface (DMI). A cet effet, nous avons utilisé la spectroscopie Brillouin (BLS) de diffusion inélastique de la lumière comme sonde expérimentale. Cette technique s’est avérée un outil extrêmement efficace pour mesurer la DMI ; effet qui se traduit par une asymétrie des raies Stokes et anti-Stokes d’un spectre BLS d’un système magnétique mince en contact d’un métal lourd produisant un fort couplage spin-orbite (SOC, acronyme anglais). Ainsi,en présence de DMI, les fréquences de deux ondes de spin se propageant dans des directions opposées seront différentes du fait de la brisure de symétrie par inversion.Différents systèmes ont été abordés et différentes situations et paramètres ont été considérés.Sur les systèmes simples en couches ultraminces, le comportement en fonction de l’épaisseur du film magnétique ou encore l’effet du recuit ont été cernés mettant en évidence le caractère interfacial de la DMI et le rôle de la qualité structurale et chimique de l’interface ferromagnétique/métal lourd. Par ailleurs, nous avons montré que l’addition d’impuretés non magnétiques à fort SOC dans des métaux légers interfacés avec un ferromagnétique peut constituer une approche efficace pour améliorer et contrôler simultanément l’amortissement magnétique, l’anisotropie perpendiculaire ainsi que la DMI. Une corrélation entre ces paramètres issus du SOC a été démontrée.Dans les empilements de couches minces, une attention particulière a été dévolue au rôle des couplages d’échange, dipolaire et des anisotropies magnétiques sur le comportement des ondes de spin en présence de DMI. Il apparaît que la mesure quantitative de la DMI peut s’écarter nettement de celle obtenue à partir de l’expression analytique éprouvée pour les couches minces simples où la valeur de la DMI est directement proportionnelle au vecteur d’onde des ondes de spin. Un calcul complet est ainsi nécessaire pour tous les cas non-symétriques (interfaces non équivalentes, anisotropies d’interface différentes,. . . ). Les résultats théoriques présentés à cet effet représentent un outil extrêmement utile.L’étude de différents réseaux de nanolignes présentant une DMI a été l’occasion de mettre en évidence les effets de taille et de périodicité dans différentes situations. Des nanolignes complètement découplées ou en contact physique partiel sur l’épaisseur ont été abordées. Nous avons ainsi mis en évidence l’absence de DMI pour des ondes de spin stationnaires selon la largeur des lignes découplées et corrélé le comportement des ondes de spin à leur longueur d’atténuation et la périodicité des réseaux, alors qu’un comportement magnonique modulé par la présence de la DMI a été observé pour les lignes couplées par l’intermédiaire d’un film ferromagnétique. Les résultats obtenus dans ce travail de thèse participent à la compréhension du comportement magnétique dynamique de systèmes en présence de DMI pouvant contribuer à l’ingénierie efficace de systèmes pour l’électronique de spin du futur ou la spin-orbitronique,notamment à base de configurations de spin chirales tels que les skyrmionsThis work aims to investigate, experimentally and theoretically, the behavior of spin waves (SW) in ultrathin layers, multilayers and magnetic nanostructures in the presence of interface Dzyaloshinskii-Moriya interaction (DMI). For this purpose, we used the Brillouin light scattering spectroscopy (BLS) as an experimental probe. This technique has proven to be an efficient tool for measuring the DMI; an effect that results in an asymmetry of the Stokes and anti-Stokes lines of a BLS spectrum for a thin ferromagnetic film in contact with a heavy metal producing a strong spin-orbit coupling (SOC). Thus, in the presence of DMI, the frequencies of two SW propagating in opposite directions will be different due to inversion symmetry breaking.Different systems were discussed and different situations and parameters were considered.On simple ultrathin layer systems, the behavior as a function of the thickness of themagnetic film or the effect of annealing have been identified, highlighting the interfacial nature of the DMI and the role of the structural and chemical quality of the ferromagnetic/heavy metal interface.Moreover, we have shown that the addition of non-magnetic impurities with high SOC in light metals interfaced with a ferromagnetic layer can be an effective approach to simultaneously improveand control magnetic damping, perpendicular anisotropy and DMI. A correlation between these SOC parameters has been also demonstrated. In thin film stacks, particular attention has been dedicated to the role of dipolar coupling,exchange coupling and magnetic anisotropy on the behavior of SW in the presence of DMI. It appears that the quantitative measurement of the DMI can deviate significantly from that obtained from the analytical expression known for simple thin layers where the value of the DMI is directly proportional to the wave vector of the SW. A complete calculation is thus necessary for all non-symmetrical cases (non-equivalent interfaces, different interface anisotropies, etc. . . ).The theoretical results presented for this purpose represent an extremely useful tool.The study of different nanostripes arrays in presence of DMI was the opportunity to highlight the effects of size and periodicity in different situations. Completely decoupled nanostripes or inpartial physical contact with periodic layer thickness were discussed. We have thus demonstrated the absence of DMI for stationary spin waves according to the width of the decoupled stripes and correlated the behavior of the SW with their attenuation length and the periodicity of the arrays, whereas a modulated magnetic behavior by the presence of the DMI was observed for the coupled stripes via a ferromagnetic film.The results obtained in this thesis work contribute to the understanding of the dynamic magnetic behavior of systems in the presence of DMI that can contribute to the efficient engineering of future systems for spintronics or spin-orbitronics, particularly based on configurations of chiral spin texture such as skyrmions
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Pihíková, Dominika. "Biopolymerem značené koloidní částice." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-216962.
Abstract:
The effect of hydrophobically modified hyaluronan on surfactants aggregation has been studied in this master’s thesis. The value of critical micelle concentration of anionic surfactant SDBS (sodium dodecylbenzensulfonate), cationic surfactant CTAB (cetyltrimethylamonnium bromide) and nonionic surfactant Triton X-100 (octylphenol ethoxylate) was determined by fluorescence spectroscopy using pyrene probe. Aggregation behavior of surfactants was performed with addition of hydrophobically modified hyaluronan of two molecular weights (17 kDa, 206 kDa) in aqueous solution. The greatest influence of hydrophobized hyaluronan on aggregation behavior was observed in system with cationic surfactant CTAB. Stability of system containing cationic surfactant and hydrophobically modified hyaluronan was established through zeta potential. Last part of thesis deals with size determination using dynamic light scattering.