Dissertations / Theses on the topic 'Raman scattering'
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Grantier, David Raymond. "Chemically induced raman scattering." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/30321.
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Maher, Robert Christopher. "Surface enhanced Raman scattering." Thesis, Imperial College London, 2007. http://hdl.handle.net/10044/1/7843.
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Petrak, Benjamin James. "Microcavity Enhanced Raman Scattering." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6354.
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Raman scattering can accurately identify molecules by their intrinsic vibrational frequencies, but its notoriously weak scattering efficiency for gases presents a major obstacle to its practical application in gas sensing and analysis. This work explores the use of high finesse (50 000) Fabry-Pérot microcavities as a means to enhance Raman scattering from gases. A recently demonstrated laser ablation method, which carves out a micromirror template on fused silica--either on a fiber tip or bulk substrates-- was implemented, characterized, and optimized to fabricate concave micromirror templates ~10 µm diameter and radius of curvature. The fabricated templates were coated with a high-reflectivity dielectric coating by ion-beam sputtering and were assembled into microcavities ~10 µm long and with a mode volume ~100 µm3. A novel gas sensing technique that we refer to as Purcell enhanced Raman scattering (PERS) was demonstrated using the assembled microcavities. PERS works by enhancing the pump laser's intensity through resonant recirculation at one longitudinal mode, while simultaneously, at a second mode at the Stokes frequency, the Purcell effect increases the rate of spontaneous Raman scattering by a change to the intra-cavity photon density of states. PERS was shown to enhance the rate of spontaneous Raman scattering by a factor of 107 compared to the same volume of sample gas in free space scattered into the same solid angle subtended by the cavity. PERS was also shown capable of resolving several Raman bands from different isotopes of CO2 gas for application to isotopic analysis. Finally, the use of the microcavity to enhance coherent anti-Stokes Raman scattering (CARS) from CO2 gas was demonstrated.
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Mohammed, Abdelsalam. "Theoretical Studies of Raman Scattering." Doctoral thesis, KTH, Teoretisk kemi (stängd 20110512), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-28332.
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Different theoretical approaches have been presented in this thesis to study the Raman scattering effect. The first one is response theory applied up to third order of polarization, where the determination of α, β and γ is used to calculate linear Raman scattering (resonance Raman scattering (RRS) and normal Raman scattering (NRS)), hyper Raman scattering (HRS) and coherent anti-Stokes Raman scattering (CARS), respectively. The response theory refers to adiabatic time-dependent density functional theory in the complex domain with applications on RRS and NRS, and to a recently developed methodology (Thorvaldsen et al. [105, 106]) for the analytic calculation of frequency-dependentpolarizability gradients of arbitrary order, here with applications on CARSand HRS. Various systems have been studied with the response theory, such as explosive substances (DNT, TNT, RDX and H2O2), optical power limiting materials (platinum(II) acetylide molecules), DNA bases (methylguanine-methylcytosine) and other systems (Trans-1,3,5-hexatriene and Pyridine). We have explored the dependency of the calculated spectra on parametrization in terms of exchange-correlation functionals and basis sets, and on geometrica loptimization. The second approach refers to time-dependent wave packet methodology for RRS and its time-independent counterpart in the Kramers-Heisenberg equation for the scattering cross section, which reduces the calculation of the RRS amplitude to computation of matrix elements of transition dipole moments between vibrational wave functions. The time-dependent theory has been used to examine RRS as a dynamical process where particular attention is paid to the notion of fast scattering in which the choice of photon frequency controls the scattering time and the nuclear dynamics. It is shown that a detuning from resonance causes a depletion of the RRS spectrum from overtones and combination bands, a situation which is verified in experimental spectra. The cross section of NRS has been predicted for the studied molecules to be in the order of 10−30 cm2/sr. A further increase in sensitivity with a signal enhancement up to 104 to 105 is predicted for the RRS technique, while CARS conditions imply an overall increase of the intensity by several orders of magnitude over NRS. In contrast to RRS and CARS, the HRS intensity is predicted to be considerably weaker than NRS, by about four orders of magnitude. However, silent modes in NRS can be detected by HRS which in turncan provide essential spectroscopic information and become complementary to NRS scattering. With the above mention methodological development for NRS, RRS, CARS and HRS, we have at our disposal a powerful set of modelling tools for the four different Raman techniques. They have complementary merits and limitations which facilitate the use of these spectroscopes in applications of Raman scattering for practical applications, for instance stand-off detection of foreign substances.QC 20110112
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Thomas, Chapman. "Autoresonance in Stimulated Raman Scattering." Phd thesis, Ecole Polytechnique X, 2011. http://pastel.archives-ouvertes.fr/pastel-00674111.
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La diffusion Raman Stimulée (DRS) est étudiée dans le contexte des plasmas qui sont pertinents pour la Fusion par Confinement Inertielle (FCI). Dans un plasma inhomogène le processus d'auto-résonance de l'onde Langmuir, générée par DRS, peut se produire dans le régime cinétique (k_L*lambda_D>0.25) et conduire à des amplitudes au delà du niveau de l'amplification attendue due à l'inhomogénéité selon Rosenbluth [M. N. Rosenbluth, Phys. Rev. Lett. 29, 565 (1972)]. On démontre que des effets cinétiques faibles, comme le piégeage d'électrons donnent lieu à un décalage de fréquence non-linéaire (dépendant de l'amplitude), et peuvent compenser le déphasage de la résonance de DRS des trois ondes, observé dans les plasmas inhomogènes. Un modèle analytique du processus d'auto-résonance décrivant à la fois la croissance, la saturation et la phase des ondes de Langmuir a été développé. Ce modèle est en excellent accord avec les résultats des simulations cinétiques (particle-in-cell) pour des paramètres proches des conditions des plasmas des expériences de la fusion laser (Laser Mégajoule, National Ignition Facility). Une application possible de l'autorésonance est proposée sous la forme d'un amplificateur de Raman.
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Narula, Rohit. "Resonant Raman scattering in graphene." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/118567.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, February 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 131-144).
In this thesis we encounter the formulation of a rigorous theory of resonant Raman scattering in graphene, the calculation of the so-obtained Raman matrix element K2f,1o for the 2D Raman mode with the full inclusion of the matrix elements and a physically appealing bridge between theory and experiment by eschewing the problematic ascription of graphene with a finite thickness. Finally, we elucidate an experimental study of the Raman D and G modes of graphene and highly-defected pencil graphite over the visible range of laser radiation. Marking a departure from the usual practice for light scattering in semiconductors of including only the dynamics of the electrons and holes separately, we show via fourth-order quantum mechanical perturbation theory using a Fock state basis that for resonant Raman scattering in graphene the processes to leading order are those that involve the simultaneous action of the electrons and holes. Such processes are indeed an order of magnitude stronger than those prevalent in the literature under the double resonance [1, 2, 3] moniker. We translate our perturbation theoretic analysis into simple rules for constructing Feynman diagrams for processes to leading order and we thereby enumerate the 2D and D modes. Using expressions for the terms to leading order obtained from our theoretical treatment we proceed to evaluate the Raman matrix element [4] for the Raman 2D mode by using state-of-the-art electronic [5] and iTO phonon dispersions [6] fit to ab initio GW calculations. For the first time in the literature we include the variation of the light-matter and electron-phonon interaction matrix elements calculated via an ab initio density functional theory (DFT) calculation under the local density approximation (LDA) for the electronic wavefunctions. Our results for the peak structure, position and intensity dependence are in excellent agreement with experiments [7, 8, 9, 10]. Strikingly, our results show that depending on the combination of the input (polarizer) and output (analyzer) polarization of the laser radiation, very different regions of the phonon dispersion are accessed. This has a direct impact on the dominant electronic transitions according to the pseudo-momentum conservation condition satisfied by the scattering of an electron by a phonon ki = kf + q. Using sample substitution [11] we deconvolve the highly wavelength dependent response of the spectrometer from the Raman spectra of graphene suspended on an SiO2 - Si substrate and graphite for the D and G modes in the visible range. We derive a model that considers graphene suspended on an arbitrary stratified medium while sidestepping its problematic ascription as an object of finite thickness and calculate the absolute Raman response of graphene (and graphite) via its explicitly frequency independent Raman matrix element [K'2f10]2 vs. laser frequency. For both graphene and graphite the [K'2f10]2 per graphene layer vs. laser frequency rises rapidly for the G mode and less so for the D mode over the visible range. We find a dispersion of the D mode position with laser frequency for both graphene and graphite of 41 cm-YeV and 35 cm-YeV respectively, in good agreement with Narula and Reich 131 assuming constant matrix elements, the observed intensity follows the joint density states of the electronic bands of graphene. Finally, we show the sensitivity of our calculation to the variation in thickness of the underlying SiO2 layer for graphene.
by Rohit Narula.
Ph. D.
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Nagata, Shinobu. "Raman Scattering in GaN and ZnO." VCU Scholars Compass, 2007. http://hdl.handle.net/10156/1970.
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Kroeger, Felix. "Stimulated Raman Scattering in Semiconductor Nanostructures." Phd thesis, Université Paris Sud - Paris XI, 2010. http://tel.archives-ouvertes.fr/tel-00561176.
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The PhD dissertation is organized in two parts. In the first part, we present an experimental study of stimulated Raman scattering in a silicon-on-insulator (SOI) nanowire. We demonstrate that the Raman amplification of a narrow-band Stokes wave experiences a saturation effect for high pump intensities because of self phase modulation of the pump beam. Moreover, an analytical model is presented that describes the experimental results remarkably well. The model furthermore provides an estimation of the Raman gain coefficient γR of silicon. The second part is devoted to the experimental study of stimulated Raman scattering in a doubly resonant planar GaAs microcavity. The nonlinear measurements clearly show some totally unexpected results. We experimentally demonstrate that the relaxation of the electrons in the conduction band of GaAs is significantly modified through the interaction with coherently excited Raman phonons.
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Huttner, Sabina Helena. "Raman scattering properties of carbon dioxide." Thesis, Cranfield University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396496.
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Lin, Wan-Ing. "Enhanced Raman scattering of molecular monolayers." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2017. http://dx.doi.org/10.18452/17758.
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Um hochsensitive räumliche Auflösung zu erreichen, wurden oberflächenverstärkte Raman-Spektroskopie (SERS) und spitzenverstärkte Raman-Spektroskopie (TERS) weiterentwickelt. Das grundlegende Funktionsprinzip ist jedoch noch nicht vollständig verstanden und auch Experimente dazu fehlen teilweise. In dieser Arbeit habe ich zuerst Gap-mode TERS eingesetzt, bei welcher ein starkes elektromagnetisches Feld es ermöglicht, dünne Schichten von sehr schwach streuenden Molekülen zu untersuchen. Mit der Nanometerauflösung von TERS konnte ein auf der Goldoberfläche spontan phasen-getrennten, gemischtes Thiolsystem räumlich aufgelöst werden, während STM die Nanodomänen nicht über ihre Höhenunterschiede erkennen konnte. Neue Studien deuten auf eine Raman-Verstärkung durch Graphen und Flachgold aufgrund eines chemischen Mechanismus hin. Kupfer Phthalocyanin (CuPc)-Moleküle zwischen Graphen und einer flachen Goldoberfläche erlauben Elektronenübertragungen in beide Richtungen und damit stellt sich die Frage, ob chemische Verstärkungen von SERS zueinander addiert werden können. Die Ergebnisse deuten auf eine Kopplung von den zwei einzelnen Oberflächen hin. Es wurde eine 68-fache Verstärkung von geschichtetem CuPc zwischen Graphen und Gold beobachtet, jeweils bezogen auf CuPc auf Glimmer. Zuletzt wurde mittels TERS diese Schichtstruktur untersucht. Moleküle, die sich auf der Goldoberfläche selbstanordnen und mit Graphen bedeckt worden sind, fungieren als optische Sensoren, bei welchen die Graphenverkapselung die Moleküle beschützt. Außerdem kann eine sehr hohe Raman-Verstärkung mit großer lokaler Auflösung aufgrund der kombinierten Effekte von SERS und TERS herbeigeführt werden. Die Ergebnisse zeigen, dass eine Spitze, die Graphen-verstärkte Raman-Streuung (GERS) zusätzlich um vier Größenordnungen verbessern kann, aber Gap-mode TERS abschirmt.The quest to achieve ultrahigh sensitivity, surface specificity and high spatial resolution has led to the development of plasmon- and chemically- enhanced Raman spectroscopy, including techniques such as surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS). However, a lack of fundamentally experimental demonstrations still remains. In this thesis, I firstly used gap-mode TERS, which allows studying even molecularly thin layers of very weakly scattering molecules. With the nanoscale spatial resolution provided by TERS, the spontaneous segregation in a mixed thiol system on a gold surface could be resolved, while scanning tunneling microscopy (STM) could not discern the nanodomains via their apparent height difference. Furthermore, since graphene and a flat gold surface both were known to provide some Raman enhancement through mainly a chemical mechanism, sandwiching copper phthalocyanine (CuPc) molecules between graphene and a flat gold surface allowed electrons to be transferred in both directions, and thereby to address the question whether chemical enhancements with different origins in SERS can add to each other. The results suggest that the chemical enhancements were influenced by the two individual surfaces, and a 68-fold enhancement of sandwiched CuPc between graphene and gold was observed, as compared to CuPc on mica. Last, TERS was applied to study this sandwiched structure. Molecules self-assembled on a gold surface and covered by transferred graphene acted as optical probes. Such an arrangement has interesting properties in the sense that molecules are protected and encapsulated by graphene. Also, a possible ultrahigh Raman enhancement together with localized spatial resolution may be achieved due to the combined effects from SERS and TERS. The results showed that a tip can improve graphene-enhanced Raman scattering (GERS) further by 4 orders of magnitude, but graphene exerts some shielding effect to gap-mode TERS.
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Nash, J. "Time resolved Raman scattering in liquid crystals using a Raman microprobe." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356443.
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Sun, Yu-Ping. "Spontaneous and stimulated X-ray Raman scattering." Doctoral thesis, KTH, Teoretisk kemi (stängd 20110512), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-32859.
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The present thesis is devoted to theoretical studies of resonant X-ray scattering and propagation of strong X-ray pulses. In the first part of the thesis the nuclear dynamics of different molecules is studied using resonant X-ray Raman and resonant Auger scattering techniques. We show that the shortening of the scattering duration by the detuning results in a purification of the Raman spectra from overtones and soft vibrational modes. The simulations are in a good agreement with measurements, performed at the MAX-II and the Swiss Light Source with vibrational resolution. We explain why the scattering to the ground state nicely displays the vibrational structure of liquid acetone in contrast to excited final state. Theory of resonant X-ray scattering by liquids is developed. We show that, contrary to aqueous acetone, the environmental broadening in pure liquid acetone is twice smaller than the broadening by soft vibrational modes significantly populated at room temperature. Similar to acetone, the "elastic" band of X-ray Raman spectra of molecular oxygen is strongly affected by the Thomson scattering. The Raman spectrum demonstrates spatial quantum beats caused by two interfering wave packets with different momenta as the oxygen atoms separate. It is found that the vibrational scattering anisotropy caused by the interference of the "inelastic" Thomson and resonant scattering channels in O2. A new spin selection rule is established in inelastic X-ray Raman spectra of O2. It is shown that the breakdown of the symmetry selection rule based on the parity of the core hole, as the core hole and excited electron swap parity. Multimode calculations explain the two thresholds of formation of the resonant Auger spectra of the ethene molecule by the double-edge structure of absorption spectrum caused by the out-of- and in-plane modes. We predict the rotational Doppler effect and related broadening of X-ray photoelectron and resonant Auger spectra, which has the same magnitude as its counterpart-the translational Doppler effect. The second part of the thesis explores the interaction of the medium with strong X-ray free-electron laser (XFEL) fields. We perform simulations of nonlinear propagation of femtosecond XFEL pulses in atomic vapors by solving coupled Maxwell's and density matrix equations. We show that self-seeded stimulated X-ray Raman scattering strongly influences the temporal and spectral structure of the XFEL pulse. The generation of Stokes and four-wave mixing fields starts from the seed field created during pulse propagation due to the formation of extensive ringing pattern with long spectral tail. We demonstrate a compression into the attosecond region and a slowdown of the XFEL pulse up to two orders of magnitude. In the course of pulse propagation, the Auger yield is strongly suppressed due to the competitive channel of stimulated emission. We predict a strong X-ray fluorescence from the two-core-hole states of Ne created in the course of the two-photon X-ray absorption.QC 20110426
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Smith, Brett. "Coherent Anti-Stokes Raman Scattering Miniaturized Microscope." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/24281.
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Microscopy techniques have been developed and refined over multiple decades, but innovation around single photon modalities has slowed. The advancement of the utility of information acquired, and minimum resolution available is seemingly reaching an asymptote. The fusion of light microscopy and well-studied nonlinear processes has broken through this barrier and enabled the collection of vast amounts of additional information beyond the topographical information relayed by traditional microscopes. Through nonlinear imaging modalities, chemical information can also be extracted from tissue. Nonlinear microscopy also can beat the resolution limit caused by diffraction, and offers up three-dimensional capabilities. The power of nonlinear imaging has been demonstrated by countless research groups, solidifying it as a major player in biomedical imaging.
The value of a nonlinear imaging system could be enhanced if a reduction in size would permit the insertion into bodily cavities, as has been demonstrated by linear imaging endoscopes. The miniaturization of single photon imaging devices has led to significant advancements in diagnostics and treatment in the medical field. Much more information can be extracted from a patient if the tissue can be imaged in vivo, a capability that traditional, bulky, table top microscopes cannot offer. The development of new technologies in optics has enabled the miniaturization of many critical components of standard microscopes. It is possible to combine nonlinear techniques with these miniaturized elements into a portable, hand held microscope that can be applied to various facets of the biomedical field.
The research demonstrated in this thesis is based on the selection, testing and assembly of several miniaturized optical components for use as a nonlinear imaging device. This thesis is the first demonstration of a fibre delivered, microelectromechanical systems mirror with miniaturized optics housed in a portable, hand held package. Specifically, it is designed for coherent anti-Stokes Raman scattering, second harmonic generation, and two-photon excitation fluorescence imaging. Depending on the modality being exploited, different chemical information can be extracted from the sample being imaged. This miniaturized microscope can be applied to diagnostics and treatments of spinal cord diseases and injuries, atherosclerosis research, cancer tumour identification and a plethora of other biomedical applications. The device that will be revealed in the upcoming text is validated by demonstrating all designed-for nonlinear modalities, and later will be used to perform serialized imaging of myelin of a single specimen over time.
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Kavanagh, Thomas Christopher. "Hyperspectral Coherent Anti-Stokes Raman Scattering Microscopy." Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/hyperspectral-coherent-antistokes-raman-scattering-microscopy(14952c6f-e333-4596-950f-29be55cbca44).html.
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Possessing high three dimensional optical sectioning capabilities and deriving chemical contrast from the intrinsic molecular vibrations of the sample, coherent anti-Stokes Raman scattering (CARS) microscopy has the ability to deliver high sensitivity non-invasive biological imaging. It is, however, accompanied by a deleterious non-resonant background (NRB) which acts to reduce the contrast and severely complicate analysis. Computational approaches are currently favoured for removing this NRB; however, these result in significant spectrally varying errors. This thesis concerns the development and subsequent implementation of a CARS platform employing a novel, all-optical, non-resonant background removal mechanism: Spectral Interferometric Polarisation Coherent Anti-Stokes Raman Scattering (SIPCARS). Exploiting the phase change that accompanies a Raman resonance and employing an elliptical pump/probe beam and linear Stokes beam, SIPCARS allows the complete removal of the NRB. The resulting SIPCARS spectra encode mode symmetry information into the amplitude response which can be directly related to polarisation resolved spontaneous Raman scattering spectra. Verification of the SIPCARS methodology was achieved using spectra acquired from pure liquid samples which were in complete agreement with the corresponding polarisation resolved spontaneous Raman scattering spectra. The multiplexing limit of the system was assessed using several multi-component polymer bead mixtures and a lower limit of four determined. High signal-to-noise ratio SIPCARS imaging of a HeLa cell in the vibrational fingerprint region was acquired, from which it was possible to identify lipid droplets and subsequently, by producing ratio images, assess their degree of lipid unsaturation and the level of oxidised lipid content. The effect of a naturally derived phytotherapeutic lipid metabolism altering drug on the lipid droplets, contained within wild type N2 Caenorhabditis elegans nematodes, was addressed using SIPCARS. Assessing lipid unsaturation and area fraction, the drug was shown to produce a marked effect: a significant reduction in storage of saturated fatty acids post exposure. Additionally the ability of SIPCARS to differentiate between a variety of different C. elegans mutants was also demonstrated. SIPCARS currently provides perhaps the only viable route to attain truly quantitative NRB-free CARS data; however, expanding on the foundation provided by this thesis, and following further development, it has the potential for profound implications in a wide range of areas including fundamental life sciences research, novel drug characterisation and histopathology.
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Huang, Qunjian. "Surface-enhanced raman scattering and surface-enhanced hyper raman scattering : a systematic study of various probing molecules on novel substrates /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202003%20HUANG.
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Arif, Mohammad. "Raman scattering studies and charge transport in polyfluorenes." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4773.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on November 21, 2007) Vita. Includes bibliographical references.
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Springett, Roger James. "Raman scattering studies of III-V semiconductor superlattices." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260178.
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Diaz, J. A. D. "Nano-structured substrates for surface-enhanced Raman scattering." Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431606.
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McCabe, Ailie Fiona. "Remote detection using surface enhanced resonance Raman scattering." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401340.
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Tsoutsi, Dionysia. "Inorganic Ions Sensing by surface-enhanced Raman scattering spectroscopy." Doctoral thesis, Universitat Rovira i Virgili, 2015. http://hdl.handle.net/10803/288213.
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En aquest projecte de tesi s'ha aconseguit desenvolupar un sistema de detecció, identificació i quantificació independent d'ions inorgànics. La detecció dels ions es basa en la diferent afinitat cap a diferents lligands orgànics mitjançant l'espectroscòpia de dispersió Raman augmentada per superfícies (surface-enhanced Raman scattering, SERS). En resum, com a substrat s'utilitzaran nanopartícules de plata o microesferes nanoestructurades que es prepararan mitjançant l'adsorció de nanopartícules d'or sobre la superfície de microesferes de sílice a partir del protocol de capa per capa i el seu posterior creixement epitaxial amb plata. Aquest últim pas es realitzarà a través de protocols desenvolupats en el nostre laboratori i té com a objectiu l'obtenció de superfícies plasmòniques discretes altament eficients en SERS. Els substrats es funcionalizaran posteriorment amb lligands orgànics tiolats amb alta afinitat per ions inorgànics (el fluoròfor orgànic, amino-MQAE i la terpiridina, pztpy-DTC). Com a pas següent, es realitzarà la detecció i quantificació simultània dels ions combinant, per a la seva detecció, espectroscòpia SERS. Els canvis espectrals SERS, en la manera de vibració dels lligands organics, estan correlacionats com a funció de la concentració de cada ió amb límits de detecció comparables als de diversos mètodes analítics convencionals.En este proyecto de tesis se ha conseguido desarrollar un sistema de detección, identificación y cuantificación independiente de iones inorgánicos. La detección de los iones se basa en su diferente afinidad hacia diferentes ligandos orgánicos a través de la espectroscopia de dispersión Raman aumentada por superficies (surface-enhanced Raman scattering, SERS). En resumen, como sustrato se utilizarán nanopartículas de plata o microesferas nanoestructuradas que se prepararán mediante la adsorción de nanopartículas de oro sobre la superficie de microesferas de sílice mediante el protocolo de capa por capa y su posterior crecimiento epitaxial con plata. Este último paso se realizará mediante protocolos desarrollados en nuestro laboratorio y tiene como objetivo la obtención de superficies plasmónicas discretas altamente eficientes en SERS. Los sustratos se funcionalizarán posteriormente con ligandos orgánicos tiolados con alta afinidad por iones inorgánicos (el fluoróforo orgánico, amino-MQAE y la terpiridina, pztpy-DTC). Como paso siguiente, se realizará la detección y cuantificación simultánea de los iones combinando para su detección espectroscopia SERS. Los cambios espectrales SERS en el modo de vibración de los ligandos orgánicos están correlacionados como función de la concentración de cada ion con límites de detección comparables a los de varios métodos analíticos convencionales.
In this research project we successfully developed a novel sensing system for the identification and quantification of inorganic ions independently by means of surface-enhanced Raman scattering (SERS) spectroscopy. The detection of the ions is based on their different affinity toward various organic ligands. In summary, we use as SERS-active substrates, either silver nanoparticles or composite nanostructured particles prepared by adsorption of gold nanoparticles on the surface of silica microbeads, using layer-by-layer assembly protocol and the subsequent epitaxial overgrowth of silver. This last step is performed using protocols developed in our laboratory and aims to the fabrication of highly plasmonic surfaces for SERS experiments. Next, the substrates are functionalized with thiolated organic ligands with high affinity toward inorganic ions (amino-MQAE, an organic fluorophore, and pztpy-DTC, a terpyridine). As a further step, the simultaneous identification and quantification of the ions, using SERS spectroscopy, is performed. Vibrational changes in the SERS spectra of the organic ligands are correlated as a function of the concentration of each ion with limits of detection comparable to those of several conventional analytical methods.
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Khaywah, Mohammad Yehia. "New ultrasensitive bimetallic substrates for surface enhanced Raman scattering." Thesis, Troyes, 2014. http://www.theses.fr/2014TROY0041/document.
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Afin de développer des capteurs ultrasensibles des substrats fiables pour la diffusion Raman exaltée de surface (SERS) ont été fabriqués. Les deux meilleurs candidats de matériaux constituant les nanoparticules pour des substrats SERS sont l’argent et l’or. L’argent présente un meilleur facteur d’exaltation de l'intensité Raman et l’or est stable dans les milieux biologiques. C’est pourquoi la combinaison de ces deux métaux dans des nanostructures bimétalliques semble être une approche prometteuse qui combine les propriétés de surface de l’or et d’exaltation de l’argent. Le recuit thermique des couches métalliques minces est utilisé comme une technique simple et peu coûteuse. Cette dernière permet d’élaborer des substrats homogènes et reproductibles de nanoparticules bimétalliques or-argent ayant un facteur d’exaltation importante. Ces nanoparticules gardent leurs propriétés d’exaltation même après une année de fabrication. En jouant sur la composition de nanoparticules bimétalliques il est possible d’avoir une résonance de plasmons de surface localisés (LSPR) sur tout le spectre visible. Ces substrats sont caractérisés par une exaltation SERS supérieure lorsque la résonance plasmon est plus proche de la longueur d'onde d'excitation Raman. En outre, les nanoparticules bimétalliques de différentes tailles, compositions ont été réalisés par lithographie électronique. L’étude systématique de leurs propriétés plasmoniques et de leur exaltation SERS a révélé une conservation du lien entre résonance plasmon et signal SERSDriven by the interest in finding ultrasensitive sensors devices, reliable surface enhanced Raman scattering (SERS) based substrates are fabricated. Silver and gold nanoparticles are two of the best candidates for SERS substrates where Ag nanoparticles exhibit large enhancing ability in Raman intensity while Au nanostructures are stable in biological systems. Hence, combining the two metals in bimetallic nanostructures appeared to be a promising approach in order to sum the merits of Au surface properties and Ag enhancing ability. Thermal annealing of thin metallic films is used as a simple and relatively inexpensive technique to elaborate homogenous and reproducible Ag/Au bimetallic nanoparticles SERS substrates with high enhancing ability. The fabricated nanoparticles proved their enhancing stability even after one year of fabrication. Manipulating the composition of Ag/Au bimetallic NPs resulted in tuning the Localized Surface Plasmon Resonance (LSPR) over the whole visible spectrum, where the substrates are characterized with higher SERS enhancement when they exhibit LSPR closer to the Raman excitation wavelength. Additionally, bimetallic nanoparticles patterns with different size, composition and lattice constants have been conducted by electron beam lithography. The systematic study of their interesting plasmonic and SERS enhancing properties revealed maintenance in the LSPR-SERS relation by changing the nanoparticle size
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Yousif, Huda. "Coherent Anti-Stokes Raman Scattering Microscopy for Biomedical Applications." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37315.
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Coherent anti-Stokes Raman scattering (CARS) microscopy is considered as a powerful tool for non-invasive chemical imaging of biological samples. CARS microscopy provides an endogenous contrast mechanism that it is sensitive to molecular vibrations. CARS microscopy is recognized as a great imaging system, especially in vivo experiments since it eliminates the need for the contrast agents.
In this thesis, CARS microscopy/spectroscopy is built from scratch by employing a single (Ti-Sapphire) laser source generating 65 femtosecond laser pulses centered at 800 nm wavelength. Two closely lying zero dispersion photonic crystal fiber (PCF) is used to generate the supercontinuum for the Stokes beam to generate CARS at 2885 cm-1 to match lipids rich vibrational frequency. XY galvanometers are used for laser raster scanning across the sample. The initial generation of CARS signal was in the forward direction. After guaranteeing a strong CARS signal, images for chemical and biological samples were taken. To achieve a multimodal imaging technique, CARS microscopy imaging system is combined with two- photon excitation fluorescent (TPEF) and second harmonic generation (SHG) imaging techniques, where various information was extracted from the imaged samples. Images with our CARS microscopy show a good resolution and sensitivity.
The second part of my work is to reduce the footprint for this setup to make it more suitable for use in clinical applications. For that reason, I integrated a homebuilt endoscope and all fiber femtosecond laser source together to get a fiber based imaging system. Proof of principal for the integrated system is achieved by obtaining a reasonable agreement in accuracy and resolution to those obtained by the endoscope driven by Ti-sapphire laser.
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Sengupta, Atanu. "Detection of biological species by surface enhanced Raman scattering /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8523.
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Minkov, Ivaylo. "Nuclear Dynamics in X-ray Absorption and Raman Scattering." Doctoral thesis, Stockholm : Theoretical Chemistry, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3902.
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Keogh, Gary Peter. "The application of coherent Raman scattering to molecular photonics." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243375.
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Baxter, Diane. "Reflectivity and Raman scattering studies of semiconductor quantum microcavities." Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284773.
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Kernohan, Edward Thomas Mark. "High resolution resonant Raman scattering in InP and GaAs." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364445.
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Harper, Mhairi. "DNA diagnostic assays using Surface Enhanced Raman Scattering (SERS)." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=22401.
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DNA is the prerequisite for all biological life and its discovery has revolutionised the understanding of biomolecular interactions and disease expression. This has enabled significant improvements in patient diagnosis and medical treatment to be carried out. The advancements in technology and instrumentation have continually progressed this knowledge and continue to push the boundaries of diagnostic and clinical advancements. One effective way to achieve this is through application of dye labelled DNA sequences and metallic nanoparticle suspensions. This research details an understanding of the interaction between dye labelled oligonucleotides and silver nanoparticle surfaces, which generate strong surface enhanced Raman scattering (SERS) responses through specific hybridisation events which correlate to the presence of targeted sequences. During this study, the attraction of oligonucleotides onto metal nanoparticles was shown to be driven through the DNA nucleobases. Therefore, the increased exposure of the base groups within single stranded DNA sequences generated a higher affinity for metal surfaces which in turn produced stronger SERS responses when compared to double stranded DNA. This principle was utilised within a DNA detection assay to successfully demonstrate the presence of target DNA sequences. Two novel DNA detection assays were also investigated which utilised SERS to determine the presence of sequences relating to the methicillin resistant Staphylococcus aureus (MRSA) strain. A solution based detection method was developed through coupling a TaqMan assay with SERS. This combination enabled highly specific detection of clinically relevant sequences of MRSA to be obtained with 7 fM limits of detection achievable. The multiple detection of different genomic S. aureus strains was achieved through the molecularly specific and narrow emission spectral profiles obtained. A contrasting DNA detection strategy which relies upon the hybridisation of comple mentary sequences on a solid substrate surface was shown. Silver nanoparticles were functionalised with specific DNA sequences and a variety of SERS active molecules, enabling the selective detection of target sequences from nitrocellulose membranes. This thesis has exploited SERS to enable the specific identification of DNA sequences to be achieved via utilisation of silver nanoparticles. Through SERS, an insight into the interactions of DNA and silver nanoparticles surfaces has been gained as well as enhancing the sensitivity and specificity achievable within SERS detection assays.
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Bégin, Steve. "Beyond imaging with coherent anti-Stokes Raman scattering microscopy." Doctoral thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/25795.
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La microscopie optique permet de visualiser des échantillons biologiques avec une bonne sensibilité et une résolution spatiale élevée tout en interférant peu avec les échantillons. La microscopie par diffusion Raman cohérente (CARS) est une technique de microscopie non linéaire basée sur l’effet Raman qui a comme avantage de fournir un mécanisme de contraste endogène sensible aux vibrations moléculaires. La microscopie CARS est maintenant une modalité d’imagerie reconnue, en particulier pour les expériences in vivo, car elle élimine la nécessité d’utiliser des agents de contraste exogènes, et donc les problèmes liés à leur distribution, spécificité et caractère invasif. Cependant, il existe encore plusieurs obstacles à l’adoption à grande échelle de la microscopie CARS en biologie et en médecine : le coût et la complexité des systèmes actuels, les difficultés d’utilisation et d’entretient, la rigidité du mécanisme de contraste, la vitesse de syntonisation limitée et le faible nombre de méthodes d’analyse d’image adaptées. Cette thèse de doctorat vise à aller au-delà de certaines des limites actuelles de l’imagerie CARS dans l’espoir que cela encourage son adoption par un public plus large. Tout d’abord, nous avons introduit un nouveau système d’imagerie spectrale CARS ayant une vitesse de syntonisation de longueur d’onde beaucoup plus rapide que les autres techniques similaires. Ce système est basé sur un laser à fibre picoseconde synchronisé qui est à la fois robuste et portable. Il peut accéder à des lignes de vibration Raman sur une plage importante (2700–2950 cm-1) à des taux allant jusqu’à 10 000 points spectrales par seconde. Il est parfaitement adapté pour l’acquisition d’images spectrales dans les tissus épais. En second lieu, nous avons proposé une nouvelle méthode d’analyse d’images pour l’évaluation de la structure de la myéline dans des images de sections longitudinales de moelle épinière. Nous avons introduit un indicateur quantitatif sensible à l’organisation de la myéline et démontré comment il pourrait être utilisé pour étudier certaines pathologies. Enfin, nous avons développé une méthode automatisé pour la segmentation d’axones myélinisés dans des images CARS de coupes transversales de tissu nerveux. Cette méthode a été utilisée pour extraire des informations morphologique des fibres nerveuses dans des images CARS de grande échelle.Optical-based microscopy techniques can sample biological specimens using many contrast mechanisms providing good sensitivity and high spatial resolution while minimally interfering with the samples. Coherent anti-Stokes Raman scattering (CARS) microscopy is a nonlinear microscopy technique based on the Raman effect. It shares common characteristics of other optical microscopy modalities with the added benefit of providing an endogenous contrast mechanism sensitive to molecular vibrations. CARS is now recognized as a great imaging modality, especially for in vivo experiments since it eliminates the need for exogenous contrast agents, and hence problems related to the delivery, specificity, and invasiveness of those markers. However, there are still several obstacles preventing the wide-scale adoption of CARS in biology and medicine: cost and complexity of current systems as well as difficulty to operate and maintain them, lack of flexibility of the contrast mechanism, low tuning speed and finally, poor accessibility to adapted image analysis methods. This doctoral thesis strives to move beyond some of the current limitations of CARS imaging in the hope that it might encourage a wider adoption of CARS as a microscopy technique. First, we introduced a new CARS spectral imaging system with vibrational tuning speed many orders of magnitude faster than other narrowband techniques. The system presented in this original contribution is based on a synchronized picosecond fibre laser that is both robust and portable. It can access Raman lines over a significant portion of the highwavenumber region (2700–2950 cm-1) at rates of up to 10,000 spectral points per second and is perfectly suitable for the acquisition of CARS spectral images in thick tissue. Secondly, we proposed a new image analysis method for the assessment of myelin health in images of longitudinal sections of spinal cord. We introduced a metric sensitive to the organization/disorganization of the myelin structure and showed how it could be used to study pathologies such as multiple sclerosis. Finally, we have developped a fully automated segmentation method specifically designed for CARS images of transverse cross sections of nerve tissue.We used our method to extract nerve fibre morphology information from large scale CARS images.
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Feng, Yejun. "Exciton spectroscopy using non-resonant x-ray Raman scattering /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/9642.
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Bryant, Mark Alan. "Surface Raman scattering of alkanethiols at silver and gold." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185702.
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The overall goal of this research is a comprehensive characterization of self-assembled alkanethiol monolayer films at Ag and Au surfaces. A combination of surface Raman spectroscopy and electrochemistry is employed to study several important aspects of these films. Raman vibrational assignments for a series of n-alkanethiols (n = 4, 5, 8, 9, 10, 12, 16, and 18 for C(n)H(2n+1)SH) are determined in the spectral regions from 600 to 1300 cm⁻¹ and 2800 to 3000 cm⁻¹. Particular emphasis is given to the trans (T) and gauche (G) ν(C-S) and ν(C-C) bands and the ν(C-H) bands. Surface Raman spectra of n-alkanethiol films at electrochemically roughened and mechanically polished, polycrystalline Ag and Au surfaces are presented. Strong enhancements of surface Raman scattering are realized at roughened surfaces, while less enhancement is observed at the mechanically polished surfaces. The conformational order of these films at these surfaces is evaluated by the determination of T and G bands present in the spectra. The orientation of these films at Ag and Au is determined through the use of surface Raman selection rules. A method is developed for the determination of orientation of C-S and C-C bonds and methyl groups. The orientations deduced using the spectral results from each of these regions are found to be self-consistent. Different orientations are deduced for alkanethiol films at Ag and Au surfaces and are proposed to be influenced by metal-S bonding. The orientations can be altered in the electrochemical environment by control of the applied potential of these metal substrates. The potential-dependent behavior is correlated with the potential of zero-excess charge (PZC) of these metals. Defect structure of these films at Ag surfaces with various surface morphologies is evaluated with Pb deposition studies. Gross films defects are evaluated with Pb underpotential deposition and ion penetration is studied with bulk Pb deposition. Finally, surface Raman spectra of monolayer films at non-enhancing surfaces are presented. Spectra for butanethiol at single-crystal Ag surfaces and butanethiol and thiophenol at mechanically polished, polycrystalline Pt surfaces show the utility of Raman spectroscopy for studying films at a variety of surfaces.
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Shan, Liye. "Stimulated Raman scattering in the evanescent field of nanofibers." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112421/document.
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Cette thèse porte sur les mélanges d’onde non linéaires qui peuvent avoir lieu dans le champ évanescent de nanofibres de silice. Nous nous sommes plus particulièrement intéressés à la diffusion Raman stimulée qui est obtenue par l’interaction du champ évanescent très intense et un liquide non linéaire dans lequel baigne la nanofibre. Afin de mettre en évidence la diffusion Raman stimulée« évanescente », nous avons développé un modèle de simulation non linéaire dont le but est de déterminer les caractéristiques des nanofibres à réaliser. Le gain Raman modal est calculé afin de trouver le rayon optimal des nanofibres pour chaque liquide ou mélange de liquides possible. En considérant la puissance critique et le seuil de dommage de nos nanofibres, nous avons déduit la longueur minimale d’interaction. Les conditions d’adiabacité des parties évasées menant à la nanofibre sont également discutées. Ces spécifications nous ont amenés à développer une plateforme de tirage de nanofibres spécifiquement dédiée à ces expériences de non-linéarités évanescentes. Cette palteforme nous permet de tirer des nanofibres de diamètre allant jusqu’à 200 nm sur des longueurs de 10 cm, avec plus de 90% de transmission. Avec ces nanofibres, nous avons mis en évidence le premier ordre Stokes de l’éthanol dans le champ évanescent d’une nanofibre, ainsi que les premier et second ordres Stokes du toluène. Ces premières expériences sont en très bon accord avec nos simulations et ouvrent la voie à de nombreuses expériences en optique non linéaireThe present PhD thesis explored nonlinear wave mixing with the strong evanescent field of nanofibers. The focus has been on the effect of stimulated Raman scattering which is activated by the interaction between such a strong evanescent field and the nonlinear liquid surrounding the nanofiber. In order to observe the stimulated Raman scattering, we investigated the nonlinear modeling to determine the needed characteristics of the nanofibers. The modal Raman gain was calculated to determine the optimal radius of nanofibers for each possible liquid. Considering the critical power and the damage threshold of our nanofibers, we found the minimum required interaction length. The condition of adiabacity of the tapers was also described. These specifications of nanofibers guide us towards the design of a proper pulling system. Several pulling systems and techniques are investigated for the fabrication of our specific nanofibers. We now are able to fabricate low loss uniform nanofibers of up to 10 cm long, a diameter down to 200 nm, with two identical low loss tapers by using our own designed translation stage pulling platform and implemented with the “variable heat brush” technique. With the achieved nanofibers, the Raman effect induced in the evanescent field was observed in both pure (ethanol) and binary mixture (toluene in ethanol) liquids. These first measurements are in good agreement with our simulation even without any fitting parameters in the modeling
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Stewart, Shona Diane. "Surface enhanced Raman scattering on electrochemically prepared silver surfaces." Thesis, Queensland University of Technology, 1999.
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Berberoglu, Halil. "Numerical Simulations On Stimulated Raman Scattering For Fiber Raman Amplifiers And Lasers Using Spectral Methods." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608986/index.pdf.
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Optical amplifiers and lasers continue to play its crucial role and they have become an indispensable part of the every fiber optic communication systems being installed from optical network to ultra-long haul systems. It seems that they will keep on to be a promising future technology for high speed, long-distance fiber optic transmission systems.
The numerical simulations of the model equations have been already commercialized by the photonic system designers to meet the future challenges. One of the challenging problems for designing Raman amplifiers or lasers is to develop a numerical method that meets all the requirements such as accuracy, robustness and speed.
In the last few years, there have been much effort towards solving the coupled differential equations of Raman model with high accuracy and stability. The techniques applied in literature for solving propagation equations are mainly based on the finite differences, shooting or in some cases relaxation methods. We have described a new method to solve the nonlinear equations such as Newton-Krylov iteration and performed numerical simulations using spectral methods. A novel algorithm implementing spectral method (pseuodspectral) for solving the two-point boundary value problem of propagation equations is proposed, for the first time to the authors'knowledge in this thesis. Numerical results demonstrate that in a few iterations great accuracy is obtained using fewer grid points.
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McAnally, Gerard David. "Analysis of polymer surfaces and thin-film coatings with Raman and surface enhanced Raman scattering." Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248360.
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Seballos, Leo B. "Raman and surface enhanced raman scattering of biomolecules and materials for hydrogen storage and delivery /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2007. http://uclibs.org/PID/11984.
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Lu, En Tzu. "Measuring and predicting model and uranyl species using normal Raman and surface-enhanced Raman scattering." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5559.
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This dissertation seeks to accurately and sensitively detect and estimate changes in molecule orientation of model and uranium species in complex samples. Currently available methods for detecting these molecules lack sensitivity, specificity, and/or require days to weeks to report trace chemical information. To overcome these limitations, normal Raman and surface-enhanced Raman scattering (SERS) are employed to gain molecular speciation. For instance, changes in uranium speciation depends on the pH and the ions present in solution. These ions form coordination complexes with uranyl, which influence the symmetric uranyl stretch that is Raman-active and can be used for the near real-time identification and relative abundance of uranium speciation in environmental samples. To accomplish this task, a strategy to extract uranyl speciation from Raman spectroscopy was developed. Important analysis methods were assessed using speciation modeling and protocols reported that minimize human subjectivity in spectral analysis. To improve detection limits of normal Raman spectroscopy, nanomaterials are employed for SERS. The adsorption of small aromatic molecules to gold coated silver nanoparticles encapsulated by internally etched silica membranes balances limitations of nanoparticle instability and orientation-dependent vibrational modes orientation relative to the plasmon resonance (electric field). Additionally, adsorption is monitored using localized surface plasmon resonance (LSPR) spectroscopy, SERS, and isotherm modeling. These combined approaches indicate that slight variations in molecular functional groups influence the free energies of adsorption of the target molecules. This provides an understanding of molecule-dependent SERS signals for sensitive, selective, and near real-time detection of small molecules in dynamic conditions. These findings support that nanomaterial surface chemistry greatly impacts molecular detection. As a result, gold nanostars functionalized with carboxyl groups are applied for uranyl detection. The distance dependent SERS response for uranyl is revealed by increasing the carbon chain length from 3-11 in the self-assembled monolayer. The shortest alkanethiol facilitated sensitive uranyl detection down to 120 nM. Finally, SERS detection is combined with electrospun amidoximated polyacrylonitrile (AO-PAN) mats to provide robust and reproducible detection of uranyl in complex matrices. AO-PAN mats are employed to initially extract and isolate uranyl while functionalized gold nanostars facilitate direct SERS detection. Characterization of AO-PAN mats uranyl uptake is examined by SEM, FT-IR and Raman spectroscopy. SERS measurements on the AO-PAN mats are obtained from matrices containing calcium and carbonate ions and synthetic urine with minimized matrix effects. Consequently, selective and sensitive detection of uranyl in environmental samples can be achieved thus broadening the scope of SERS for practical use.
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Norman, Rachel. "Simultaneous detection of multiple explosives using surface enhanced Raman scattering." Thesis, University of Strathclyde, 2016. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27074.
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There remains a continuing threat of terrorist/insurgent attacks on military/civilian personnel and key strategic infrastructures both within the UK mainland and in operational theatres. The development of a novel, innovative, low cost, field deployable bionanosensor, which will have the capability to detect low levels of explosive in a multiplexed fashion is required. The use of the specific interaction between small molecules and biological capture molecules such as antibodies coupled with the detection technique of surface enhanced Raman scattering (SERS) allows a ‘one shot’ analysis. This research makes use of antibody functionalised silver nanoparticles for the detection of the explosives TNT, RDX and PETN by surface enhanced Raman scattering (SERS). Commercially available antibodies specific for TNT and RDX have been modified to specifically orientate ‘flat’ on the surface of silver nanoparticles bringing the target close enough to the metal surface to allow an intrinsic SERS signal of the target molecule to be obtained. Quantitative detection of TNT and RDX explosives was achieved, with pM sensitivity demonstrated for RDX. Furthermore, TNT was detected in two different types of dirt, natural and synthetic dirt in order to mimic a more realistic matrix in which TNT would be found in the field. However, for the detection of PETN, it was required to develop a method to modify a PETN antibody in-house, to specifically orientate ‘flat’ on the nanoparticles surface similarly to the commercially available antibodies. This was achieved by using carbodiimide chemistry and the antibody was purified by cartridge centrifugation and HPLC. The PETN modified antibody was then functionalised onto silver nanoparticles and detection of PETN was achieved by SERS. In addition, PCA was used to allow multiplexed analysis based on unique Raman bands for the three different explosives which could be clearly identified in the SERS spectra. Finally, TNT was detected by using magnetic nanoparticles which were functionalised with a terminal amine group in combination with FITC modified TNT antibody functionalised silver nanoparticles. This assay was designed to allow for the formation of a Meisenheimer complex in the presence of TNT, between the amine functionalised magnetic nanoparticles and the TNT. Furthermore, the TNT antibody functionalised silver nanoparticles also binds to TNT, aggregating the nanoparticles. The magnetic nanoparticles were subsequently used to remove the nanoparticle assembly from the matrix, resulting in a concentrated sample on the magnet, resulting in an increase in SERS.
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Tay, Li-Lin. "Towards near-field single molecule surface enhanced Raman scattering detection." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0029/NQ53683.pdf.
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Ji, Wenhai. "Stimulated Raman scattering in atomic ensembles : toward quantum state entanglement /." view abstract or download file of text, 2007. http://proquest.umi.com/pqdweb?did=1417817761&sid=2&Fmt=2&clientId=11238&RQT=309&VName=PQD.
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Thesis (Ph. D.)--University of Oregon, 2007.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 251-264). Also available for download via the World Wide Web; free to University of Oregon users.
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Marshall, Bruce Russell. "Raman scattering in ocean water." 1989. http://catalog.hathitrust.org/api/volumes/oclc/24084207.html.
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Wardle, David. "Raman scattering in optical fibres." 1999. http://hdl.handle.net/2292/433.
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The Raman effect is the inelastic scattering of photons by matter. When a monochromatic light beam (pump beam) propagates in an optical fibre, spon- taneous Raman scattering transfers some of the photons to new frequencies. The probability of a photon scattering to a particular frequency shift, depends on that frequency shift, forming a characteristic spectrum. The scattered photons may lose energy (Stokes) or gain energy (anti-Stokes). If the pump beam is linearly polarized, then the polarization of scattered photons may be the same (parallel scattering) or orthogonal (perpendicular scattering). If photons are already present at other frequencies then the probability of scattering to those frequencies is enhanced (stimulated scattering). In this thesis, the equations governing the Raman effect, both in bulk glass and single mode fibre, are restated. The probability of spontaneous scattering (parallel and perpendicular) in an optical fibre has been measured for frequency shifts between 4THz and 58THz. Particular attention has been given to those frequency shifts where the scattering is intrinsically weak. This has identified those frequency shifts where it might be possible to eliminate Raman noise from experiments designed to generate quantum states of light in optical fibres using four wave mixing. From the measured scattering probabilities, the Raman equations can be used to predict the scattering cross-section in bulk glass. The prediction is found to be in reasonable agreement with measurements of the bulk glass cross-section published by other authors. By increasing the pump power, the transition to stimulated scattering has been observed. In the case of Stokes scattering there is reasonable agreement between the Raman equations and experimental observations. In the case of anti-Stokes scattering, and in the limit of very high pump power, behaviour is observed which is not predicted by the Raman equations, indicating that other processes must be included to successfully describe such experiments.
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Shiri, Pricciard Roy. "Raman scattering in carbon nanotubes." Thesis, 2009. http://hdl.handle.net/10539/6733.
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Analysis of peak shifts of Raman vibrational modes in single-walled carbon nan-
otubes (SWCNTs) gives important information about the vibrational properties of
SWCNTs, which in turn gives a deeper understanding of the physical, electronic
and thermal properties of SWCNTs.
In this work, the temperature dependence of the frequencies and linewidths of
the vibrational modes of semi-conducting and metallic nanotubes were studied using
Raman spectroscopy. The SWCNTs used here were synthesized using the electric-
arc discharge method. Two laser lines, the 514.5 nm and 488.0 nm were used to
exploit the resonances of the semi-conducting tubes and the 647.1 nm was used to
excite metallic SWCNTs.
The radial breathing mode (RBM) peak positions of semi-conducting and metal-
lic tubes were observed to decrease at di®erent rates with increasing temperatures.
The line shapes of the RBMs also change signi¯cantly with changes in temperatures.
The G+ and G¡ peaks of the tangential modes (G-band) of semi-conducting and
metallic nanotubes also decrease at di®erent rates with increasing temperatures.
A comparison of the rates of change of mode frequency of the G+ and G¡ modes
in metallic and semi-conducting nanotubes gives more insight into the role played
by electron-phonon coupling and plasmon-phonon coupling in each case. It gives
a deeper insight into the contentious issue of mode assignment of the G+ and G¡-modes of metallic SWCNTs.
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LIN, LIAN-XING, and 林聯興. "The raman scattering of KNaSO4." Thesis, 1989. http://ndltd.ncl.edu.tw/handle/71383179854316376216.
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Chou, He-Chun. "Enhancement of Raman signals : coherent Raman scattering and surface enhanced Raman spectroscopy." Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-05-5476.
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Raman spectroscopy is a promising technique because it contains abundant vibrational chemical information. However, Raman spectroscopy is restricted by its small scattering cross section, and many techniques have been developed to amplify Raman scattering intensity. In this dissertation, I study two of these techniques, coherent Raman scattering and surface enhanced Raman scattering and discuss their properties. In the first part of my dissertation, I investigate two coherent Raman processes, coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS). In CARS project, I mainly focus on the molecular resonance effect on detection sensitivity, and I find the detection sensitivity can be pushed into 10 [micromolar] with the assistance of molecular resonance. Also, I am able to retrieve background-free Raman spectra from nonresonant signals. For SRS, we develop a new SRS system by applying spectral focusing mechanism technique. We examine the feasibility and sensitivity of our SRS system. The SRS spectra of standards obtained from our system is consistent with literature, and the sensitivity of our system can achieve 10 times above shot-noise limit. In second part of this dissertation, I study surface enhanced Raman scattering (SERS) and related plasmonic effects. I synthesize different shapes of nanoparticles, including nanorod, nanodimer structure with gap and pyramids by template method, and study how electric field enhancement effects correlate to SERS by two photon luminescence (TPL). Also, I build an optical system to study optical image, spectra and particle morphology together. I find that SERS intensity distribution is inhomogeneous and closely related to nanoparticle shape and polarization direction. However, TPL and SERS are not completely correlated, and I believe different relaxation pathways of TPL and SERS and coupling of LSPR and local fields at different frequencies cause unclear correlation between them.text
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Wen, Ching-Chong, and 文靖中. "Long Distance Stimulated Raman Scattering and Surface Enhanced Raman Detection." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/34042090409041898634.
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碩士國立陽明大學
生醫光電工程研究所
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Raman scattering is widely used in measuring the specific vibrational bonds of a (organic) sample to reveal its chemical structure. Stimulated Raman scattering (SRS) can enhance the signal through the mechanism of stimulated emission. Both Raman and stimulated Raman scattering are a third-order nonlinear optical process. SRS is highly sensitive and its strength depends on both incident light beams. This study is aimed to take advantage of the coherence stimulated Raman scattering in improving the working distance and the efficiency in scanning a large area. The long distance detection setup is using low numerical aperture optics in detecting SRS, at the cost of high spatial -resolution available for optical microscope. In this way, the working distance is stretched in achieving a much wider field of view and the efficiency of scanning a large area is greatly enhanced. This study demonstrates the feasibility of applying long distance stimulated Raman scattering. An oil-water mixture and polystyrene beads are used to illustrate the feasibility. To further enhance the SRS, the effect of surface plasmon enhancement is adopted by adding gold nanoparticles to the sample. The electron plasma of gold nanoparticles resonates with the incident electric field and thus increase the intensity of the incident and scattered light.
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Chao, Chi Tse, and 趙啟喆. "Heterodyne Interference Stimulated Raman Scattering Spectroscope." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/vxg9qu.
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Lin, Kun-Zheng, and 林坤政. "Temperature-dependent Raman scattering of ZnSeO." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/65299621851060405488.
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碩士國立中央大學
物理學系
101
The oxygen concentrations of ZnSe1-xOx alloys studied in this thesis are in the range of 1.5%x11.6%. Because of the limited oxygen solubility, Nabetani had proposed that ZnSeO alloy composition up to 6.4%. Our highest concentration up to 11.6%.In our previous study indicate the results of photoluminescence (PL) indicate that the relationship between band gap and oxygen composition can be well described in the framework of band anti-crossing model (BAC model). However, the full width of half maxima (FWHM) of signals becomes broader and the intensities become weaker in the higher O concentration range. These results indicate that the crystal structures may have changed. Thus we investigated the crystal structure via Raman spectrum. In 10K Raman scattering experiments, the phonon frequency is influenced by strain and effective mass. With ZnSe mixes O, the phonon frequency become slower than ZnSe, but when oxygen concentration higher than 9.3%, the frequency is dominated by effective mass. The phonon frequency becomes faster. In temperature-dependent Raman scattering, we can find as the oxygen concentration increases, the anharmonic effect will increase. Besides, the FWHM of LOZnSe becomes broader than ZnSe. In the end, we will discuss optical phonon life time. When increasing the oxygen concentration, the life time will become shorter than ZnSe.
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Wei, Lijuan. "Microbead-based Raman/surface enhanced Raman scattering immunoassays for multiplex detection." Thesis, 2014. http://hdl.handle.net/2440/92665.
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The aim of this thesis project was to develop polymer microbead-based Raman/surface enhanced Raman scattering (SERS) immunoassay systems for the multiplex, specific and sensitive detection of biological molecules. Immunoglobulin G (IgG) was used as model proteins. In the system, gold nanoparticles (AuNPs) serve as SERS-active substrates. Different Raman-active molecules, such as 4-mercaptobenzoic acid (4MBA), can be easily self-assembled on the AuNPs as SERS tags. Polymer microbeads offer as immune-solid supports and provide Raman signatures. This study focused on the fabrication of different SERS tags, SERS-active microbeads and Raman spectroscopic-encoded microbeads for microbead-based Raman/SERS immunoassay development. Polymer microbead-based Raman/SERS immunoassay system was first developed using 50 nm AuNPs and 130-600 μm carboxylated polystyrene (PS) microbeads synthesised by suspension polymerisation. Antibodies (FITC-labelled donkey anti-goat IgG) were conjugated to polymer microbeads by EDC/NHS coupling chemistry. The SERS tags were comprised of Raman-active molecules (4MBA) and AuNPs. Antigens (DyLight™649- labelled goat anti-human IgG) were successfully conjugated on SERS tags to form SERS reporters. The immunoassay was performed by mixing the protein conjugated polymer microbeads and SERS reporters together. Due to the specific recognition between antibody and antigen, AuNPs can be attached on the surface of polymer microbeads. The results were verified using fluorescence imaging and Raman/SERS analysis. Since flow cytometry can rapidly sort large number of cells and particles in a short time, our intention was to take the advantages of both flow cytometry and Raman effects to develop Raman flow cytometry for multiplex and rapid detection. Therefore, monodisperse polymer microbeads with unique Raman signatures need to be synthesised. The preparation of the monodisperse polymer microbeads with specific Raman signatures was carried out by two approaches. Firstly, the SERS-active microbeads were synthesised by the deposition of AuNPs on the surface of polymer microbeads and the addition of the Raman-active molecules prior to silica coating. The preparation of polystyrene microbead/AuNP composite microspheres was achieved through two methods (direct adsorption and in-situ growth). The mechanism for the silica coating of polystyrene/AuNP composite microspheres was discussed in details. 4-mercaptophenol (4MP) was self-assembled on the composite microspheres, followed by silica coating to obtain the SERS-active microbeads. Secondly, the Raman spectroscopic-encoded copolymer microbeads were fabricated using styrene (Sty), 4-tertbutylstyrene (4tBS), and 4-methylstyrene (4MS) by dispersion polymerisation. Acrylic acid (AA) was used as the co-monomer to generate carboxyl groups on the surface of polymer microbeads. Six kinds of copolymer microbeads with the average diameters between 1.07 and 1.69 μm, including poly(Sty-AA), poly(Sty-4tBS-AA), poly(4tBS-AA), poly(Sty-4MS-AA), poly(4MS-AA), and poly(4tBS-4MS-AA), were synthesised with narrow size distribution and unique Raman fingerprints, which could be employed as spectroscopic-encoded microbeads in microbead-based Raman/SERS immunoassay system. Monodisperse polystyrene microbeads with 1.6 μm diameter were also used to perform the polymer microbead-based Raman/SERS immunoassays. A similar immunoassay system as previous was applied for IgG recognition based on AuNPs and monodisperse PS microbeads, which were sorted and analysed using flow cytometry and Raman equipment. In summary, the thesis proposed a new strategy for multiplex detection and reported the preliminary studies on polymer microbead-based Raman/SERS immunoassay. Different SERS-active microbeads and Raman spectroscopic-encoded copolymer microbeads have been successfully synthesised.Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering, 2014
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Jackson, Joseph Bryan. "Surface enhanced Raman scattering with metal nanoshells." Thesis, 2004. http://hdl.handle.net/1911/18648.
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A systematic investigation of surface enhanced Raman scattering (SERS) was performed using metal nanoshells as the substrate. Nanoshells are a dielectric sphere coated with a thin metal shell, which have a well understood, geometrically tunable plasmon resonance. This tunability allows for the engineering of the optical near field for SERS. A simple model connecting the nanoshell electromagnetic near field at the incident frequency to that at the Raman shifted frequency is discussed. This theory is compared to the measured SERS response of the nonresonant molecule para-mercaptoaniline (pMA) adsorbed on silver and gold nanoshells.
Using a solution of silver nanoshells, at an excitation wavelength of 1064 nm enhancements on the order of 106 to 108 were observed. Accounting for reabsorption of the Raman scattered light as it traverses the solution suggests enhancements of 1012.
To mitigate the reabsorption, film geometries were investigated. For film measurements a 782 nm excitation laser was used. The SERS response of a dense film of silver nanoshells followed the calculated single nanoshell response of the nanoshells whose plasmon resonance was tuned near the excitation wavelength. In contrast, for nanoshells blue shifted from the excitation laser, the film Raman response followed an estimated dimer response.
The Raman response as a function of nanoshell density was studied using films of gold nanoshells dispersed on the surface of polyvinylpyridine (PVP) coated glass slides. A linear dependence of the Raman modes on the nanoshell density was observed confirming that the single nanoshell plasmon dominates the SERS response. The SERS enhancements for nanoshell films calculated by direct comparison to an unenhanced measurement were on the order of 10 10 to 1012.
The Raman response as a function of incident intensity was measured for dense silver nanoshell films. An optical pumping model allowing for stimulation of the Raman emission is proposed. Using this model, an effective unenhanced Raman cross section of the order of 10-27 cm2 is found. This is comparable to cross sections obtained in unenhanced Raman measurements. Evidence for two photon photoluminescence by nanoshells is presented. It is proposed the Raman emission is stimulated by the two photon photoluminescence.