Academic literature on the topic 'Approximation de Raman'

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Journal articles on the topic "Approximation de Raman"

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Sobti, Lokesh, Vaibhav Arora, and Hardeep Singh. "Linear Power Division Approximation for Stimulated Raman Scattering." Fiber and Integrated Optics 33, no. 4 (2014): 299–305. http://dx.doi.org/10.1080/01468030.2014.914264.

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Peterson, P. R., and A. Gavrielides. "Raman ring resonator stability in the adiabatic approximation." Journal of the Optical Society of America B 7, no. 1 (1990): 101. http://dx.doi.org/10.1364/josab.7.000101.

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Shamrov, N. I. "Quasiresonance approximation for cooperative raman scattering of light." Journal of Applied Spectroscopy 63, no. 1 (1996): 71–74. http://dx.doi.org/10.1007/bf02606628.

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Davies, John A., Ronald C. Davidson, and George L. Johnston. "Compton and Raman free electron laser stability properties for a cold electron beam propagating through a helical magnetic wiggler." Journal of Plasma Physics 33, no. 3 (1985): 387–423. http://dx.doi.org/10.1017/s0022377800002580.

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This paper gives an extensive characterization of the range of validity of the Compton and Raman approximations to the exact free electron laser dispersion relation for a cold, relativistic electron beam propagating through a constantamplitude helical wiggler magnetic field. The electron beam is treated as infinite in transverse extent. Specific properties of the exact and approximate dispersion relations are investigated analytically and numerically. In particular, a detailed numerical analysis is carried out to determine the range of validity of the Compton approximation.
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Choi, Jun-Ho, and Minhaeng Cho. "Amide I Raman optical activity of polypeptides: Fragment approximation." Journal of Chemical Physics 130, no. 1 (2009): 014503. http://dx.doi.org/10.1063/1.3050294.

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Nafie, Laurence A. "Theory of Raman scattering and Raman optical activity: near resonance theory and levels of approximation." Theoretical Chemistry Accounts 119, no. 1-3 (2007): 39–55. http://dx.doi.org/10.1007/s00214-007-0267-9.

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Impellizzeri, A., A. A. Vorfolomeeva, N. V. Surovtsev, A. V. Okotrub, C. P. Ewels, and D. V. Rybkovskiy. "Simulated Raman spectra of bulk and low-dimensional phosphorus allotropes." Physical Chemistry Chemical Physics 23, no. 31 (2021): 16611–22. http://dx.doi.org/10.1039/d1cp02636d.

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The Placzek approximation with DFT accurately reproduces experimental Raman spectra for phosphorus allotropes. We explain bulk allotrope spectral features in black and white phosphorus, and predict spectra for phosphorus nanostructures.
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Володин, В. А., В. А. Сачков та М. П. Синюков. "Запрещенное резонансное комбинационное рассеяние света в сверхрешетках GaAs/AlAs: эксперимент и расчеты". Физика и техника полупроводников 52, № 6 (2018): 569. http://dx.doi.org/10.21883/ftp.2018.06.45917.8671.

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AbstractThe Raman spectra of GaAs/AlAs(100) superlattices are calculated and studied experimentally for various wave-vector directions. The experiments are performed when applying a confocal optical microscope combined with a micro-Raman spectrometer for various scattering geometries both for phonons with a wave vector directed along the normal to a superlattice and in the in-plane geometry. The frequencies and eigenvectors of phonons are calculated in the extended Born model approximation taking into account Coulomb interaction in the rigid-ion approximation. The Raman spectra are calculated in the scope of the deformation- potential mechanism; herewith, it turns out that additional peaks, which are not described in the scope of this approach, appear in the experimental spectra. It seems likely that these peaks appear due to the manifestation of Raman scattering forbidden by selection rules under resonance conditions. An attempt is made to explain the appearance of these peaks in the experimental spectra within the scope of inelastic phonon scattering at bound charges (phonons with a large dipole moment).
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Jirkovský, Jakub, Kateřina Macounová, Hartmut Dietz, Waldfried Plieth, Petr Krtil, and Stanislav Záliš. "Raman Spectroscopy of Nanocrystalline Li-Ti-O Spinels and Comparative DFT Calculations on TiyOz and LixTiyOz Clusters." Collection of Czechoslovak Chemical Communications 72, no. 2 (2007): 171–84. http://dx.doi.org/10.1135/cccc20070171.

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Raman spectra of cubic nanocrystalline insertion hosts in Li-Ti-O system were measured for Li1.1Ti1.9O4-δspinels and the corresponding delithiated titanium dioxide material. To interpret the measured data optimized geometries of cubic TiyOzand LixTiyOzwere calculated using the DFT cluster approach for clusters containing up to 23 atoms. The calculated geometries were used to predict the density-of-states (DOS) diagrams and vibrational spectra of the corresponding structures upon harmonic approximation. While the DFT approach reproduces satisfactorily the main structural characteristics of TiyOzclusters, the agreement in the case of LixTiyOzclusters between calculated and real structures is less satisfactory due to the small cluster size. The band gap energies obtained from DOS diagrams represent overestimates of the actual experimental band gap energies measured on cubic Li-Ti-O oxides. The agreement between calculated and measured band gap energy improves with increasing cluster size. Raman spectra calculated under harmonic approximation from the optimized geometries reproduce all important features of the experimental Raman spectra. The agreement of DFT-calculated and experimental Raman spectra improves with increasing size of the cluster.
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Thang, Nguyen Manh. "Appearance of an ensemble solitary pulse train in transient backward stimulated Raman scattering." Communications in Physics 25, no. 3 (2016): 275. http://dx.doi.org/10.15625/0868-3166/25/3/6770.

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A self-similarity approximation model for three-wave resonant interaction in transient backward stimulated Raman scattering (BSRS) was derived. Interestingly, as its asymptotic solution, the train of solitary backward Raman pulse train is possibly formed. This result can be considered as an increment of “single” soliton observed previously [A. Abdolvand et al., Phys. Rev. Lett 103, 183902 (2009)].
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Dissertations / Theses on the topic "Approximation de Raman"

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Perez, Florent. "Plasmons dans un potentiel unidimensionnel : étude par spectroscopie Raman de fils quantiques gravés." Paris 6, 1998. http://www.theses.fr/1998PA066724.

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Perez, Florent. "Plasmons dans un potentiel unidimensionnelEtude par spectroscopie Raman de fils quantiques gravés." Phd thesis, Université Pierre et Marie Curie - Paris VI, 1998. http://tel.archives-ouvertes.fr/tel-00285443.

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Nous avons étudiés des fils quantiques dopés de semi-conducteurs gravés par spectroscopie de diffusion Raman. Nous avons observés les excitations du gaz d'électrons. Celles-ci présentent des règles de sélection différentes de celles établies pour les systèmes bi-dimensionnels. Nous avons montré théoriquement qu'elles proviennent de la modification de la structure du champ électromagnétique local provoquée par la géométrie particulière des fils gravés. Pour cela nous avons dû calculer le champ local et l'introduire dans la section efficace de diffusion Raman pour en déduire les règles de sélection de toutes les excitations. Cela a permis de déterminer sans équivoque la nature des excitations qui sont des plasmons. Aucune excitations à une particule ni fluctuations de densité de spin n'a été observées. Nous avons étudié l'évolution continue des dispersions de ces plasmons lorsque la largeur du fil est réduite de 1 micromètre à 30 nm. Jusqu'à 60 nm, celles-ci sont en très bon accord avec les résultats d'un modèle hydrodynamique. Au dessous de 60 nm, la comparaison avec un modèle RPA s'impose. Le plasmon intra-bande dispersif est observé jusqu'à 45 nm, largeur en dessous de laquelle les spectres Raman sont dominés par des excitations localisées qui nécessitent une analyse ultérieure pour en déterminer clairement leur nature. Nous montrons à l'aide du modèle RPA que nous avons atteint la limite quantique pour un fil de largeur 55 nm. Une gamme étroite de fils dont les largeurs sont comprises entre 55 nm à 45 nm permet donc l'étude de gaz strictement unidimensionnel.<br />Nous avons cherché à déterminer la contribution de la forte illumination dans les conclusions précédentes. Nous avons utilisé pour cela la spectroscopie de magnéto-transmission infra-rouge qui ne modifie pas les conditions d'équilibre du gaz d'électrons. Une largeur critique de 130 nm a été extraite, en dessous de laquelle nous n'avons plus aucun signe de la présence d'électrons libres. La comparaison des mesures Raman et infra-rouge a permis l'établissement et la validation d'un modèle microscopique du potentiel de confinement présent dans les fils. Enfin nous avons fabriqués des échantillons de géométries plus complexes. L'observation et l'analyse par diffusion Raman des plasmons dans ces fils a montré que nous pouvions contrôler la géométrie du potentiel confinant les électrons et a mis en évidence des effets nouveaux tels que le repliement et le confinement de plasmons unidimensionnels.
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Petsas, Konstantinos I. "Atomes ultrafroids dans des réseaux de lumière : étude théorique du magnétisme, de la température et des structures multidimensionnelles." Phd thesis, Université Pierre et Marie Curie - Paris VI, 1996. http://tel.archives-ouvertes.fr/tel-00011909.

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Cette thèse s'inscrit dans le cadre de l'étude théorique des réseaux optiques brillants et gris, par des modèles uni- ou multidimensionnels. Nous présentons d'abord une méthode d'élaboration et de classification systématique des réseaux optiques multidimensionnels en utilisant des arguments de cristallographie. Une approche semi-classique basée sur des simulations de Monte-Carlo est ensuite mise au point dans le cadre des réseaux optiques unidimensionnels pour diverses transitions atomiques. Ce modèle, ainsi que le modèle quantique des bandes, sont utilisés pour l'étude de la température et du magnétisme des réseaux optiques brillants et gris. Le comportement magnétique général trouvé est en bon accord avec des expériences récentes. Nous étudions enfin un nouveau type de réseau gris bidimensionnel, comportant une structure périodique d'antiplots. La dynamique atomique au sein de ce réseau est analysée au moyen de spectroscopie pompe-sonde, permettant de mettre en évidence un comportement dynamique très original.
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Sopena, Moros Arturo. "Etude des effets relativistes en régime d’interaction non-linéaire entre les molécules et les impulsions laser brèves dans les domaines de fréquences XUV et X mous." Thesis, Bordeaux, 2021. http://www.theses.fr/2021BORD0131.

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Le développement des sources XUV intenses du type laser à électrons libres (LEL) et génération d’harmoniques d’ordre élevé (GHOE) en régime femtoseconde (fs) et sub-fs permet l’investigation des processus non-linéaires ultra rapides dansl’interaction laser-matière. Dans le contexte de l’étude de la dynamique de la photoionisation moléculaire aux temps ultra-brefs, la résolution directe de l’équation de Schrödinger dépendante du temps (ESDT) s’est révélée cruciale pour l’interprétationdes observations expérimentales. Dans cette thèse, nous présentons des calculs ab-initio pour la photo-ionisation de H2 en impulsion ultra-brève UV et X. On s’intéressera plus particulièrement aux processus non-linéaires impliquant deux photons,à leur rôle dans le couplage dynamique électron-noyaux ainsi qu’aux effets liés aux corrections à l’approximation dipolaire (AD).Notre approche théorique est basée sur la méthode spectrale, elle nécessite la détermination des états quantiques de la molécule isolée. Ces états sont calculés dans l’approximation Born-Oppenheimer (BO) dans le contexte de la méthode d’interaction de configuration, en s’appuyant sur la théorie des collisions pour traiter les continua et sur le formalisme de Feshbach pour calculer les états autoionisants. Dans le traitement de l’interaction avec le rayonnement, nous nous basons sur un développement multipolaire du vecteur potentiel du champ en jauge de Coulomb, dont nous conservons les termes correspondant à l’AD et aux effets de retard jusqu’à l’ordre O(1/c). Finalement, nous utilisons des approches perturbatives et nonperturbatives pour obtenir l’amplitude de transition liée à l’ionisation, à partir de laquelle on calcule les sections efficaces, les spectres de photoélectrons et les distributionsangulaire dans le référentiel de la molécule [...]<br>The development of intense XUV sources through free-electron lasers (FELs) and high-order harmonic generation (HHG) in the femtosecond (fs) and sub-fs domains provides a unique tool to investigate non-linear ultrafast laser-matter interaction. In the study of the dynamics of molecular photoionization at ultrashort timescales, the Time-Dependent Schrödinger Equation (TDSE) has been crucial for the interpretation of experimental observations. In this thesis, we present results for ab initio calculations of H2 photoionization with UV/X-ray ultrashort laser pulses. We focus on the study of non-linear processes involving two photons and their role in the coupled electron-nuclear dynamics they induce and their study beyond the dipole approximation (DA). Our theoretical approach is based on a spectral method, which requires determining the quantum states of the field-free molecule. These states are calculated in the Born-Oppenheimer approximation employing a configuration interaction scheme together with multichannel scattering theory to determine for the treatment of continuum states, and the Feshbach partitioning formalism to account for autoionization. We resort to a multipolar expansion of the vector potential in the Coulomb gauge, from which we keep the terms corresponding to DA and retardation effects up to O(1/c), to account for the interaction with radiation. Finally, we make use of perturbative and non-perturbative propagation schemes to obtain transition amplitudes from which we can extract cross-sections, photoelectron spectra (PES), and molecular frame angular distributions (MFPADs).In the first part of the results, we demonstrate the coherent control of ionization and dissociation achieved by filtering the higher harmonics in an attosecond pulse train (APT) in an XUV pump-UV probe scheme. By solving the TDSE in DA including electronic and nuclear motion, we are able to extract nuclear and electronic kinetic energy release (KER) spectra to analyze the main ionization pathways as afunction of the delay between pump and probe. We then discuss the effect of harmonic filtering in manipulating one-photon against two-photon ionization yields, dissociative ionization channels, and asymmetries in the MFPADs. In the second part of the results of the thesis, we report the first calculations of Stimulated Raman Scattering (SRS) and Stimulated Compton Scattering (SCS) in H2 with intense X-ray laser fields. These non-linear phenomena consist in the absorption of a photon and the subsequent stimulated emission of a less energetic one leaving the molecule in an excited state (SRS) or effectively ionizing it (SCS). Theoretically, the inclusion of effects beyond DA becomes mandatory. We begin by investigating the relative role of the dipole (A.P) and non-dipole (A2) interaction terms through a perturbative study of the Raman cross-section. The role of the high energy electronic continuum in the partial cancellation of the dipole contribution is also analyzed. We then present results from SRS and SCS calculations using ultra-short pulses in which we compare the relative contribution of the dipole and non-dipole routes as a function of the photon energy. We assert the validity of perturbation theory by directly comparing SRS calculations with results obtained by solving the TDSE. In SCS, the interference between dipole and non-dipole routesproduces asymmetries in the MFPADs, which we analyze. Special attention is givento the effect of molecular orientation.Finally, we study SCS with two colors, focusing on the effect of the angle between the pulse propagation directions. As seen in atoms, non-dipole effects are enhanced for counter-propagating pulses. We also investigate the effect of color separation in energy
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Henkel, Carsten. "Réflexion et diffraction d'atomes lents par un miroir à onde évanescente." Phd thesis, Université Paris Sud - Paris XI, 1996. http://tel.archives-ouvertes.fr/tel-00006757.

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Une onde évanescente lumineuse permet de réaliser un miroir à atomes, à condition que ceux-ci soient incidents avec une énergie cinétique suffisamment faible. Dans le régime de faible saturation, les atomes sont réfléchis de façon cohérente par un potentiel répulsif, le potentiel dipolaire. Nous caractérisons la réflexion d'un point de vue quantique, moyennant une solution analytique de l'équation de (\sc Schrödinger). La théorie de la diffraction d'atomes par une onde évanescente stationnaire est développée. Nous introduisons l'approximation du réseau de phase mince, valable dans le régime semi-classique, qui montre qu'en incidence normale la diffraction est efficace pour une faible modulation spatiale de l'intensité lumineuse. Pour interpréter la diffraction d'atomes en incidence rasante, il faut prendre en compte des transitions (\sc Raman) stimulées entre les sous-niveaux magnétiques. La réflexion atomique devient diffuse lorsque la rugosité de la surface du diélectrique, au-dessus de laquelle se propage l'onde évanescente, dépasse la longueur d'onde atomique incidente. La distribution angulaire des atomes diffusés donne accès à la densité spectrale de rugosité pour des échelles spatiales autour de la longueur d'onde lumineuse.
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Huynh, Dan-Nha. "Nonlinear optical phenomena within the discontinuous Galerkin time-domain method." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19396.

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Diese Arbeit befasst sich mit der theoretischen Beschreibung nichtlinearer optischer Phänomene in Hinblick auf das (numerische) unstetige Galerkin-Zeitraumverfahren. Insbesondere werden zwei Materialmodelle behandelt: das hydrodynamische Modell für Metalle und das Modell für Raman-aktive Materialien. Im ersten Teil der Arbeit wird das hydordynamische Modell für Metalle unter Verwendung eines störungstheoretischen Ansatzes behandelt. Insbesondere wird dieser Ansatz genutzt, um die nichtlinearen optischen Effekte, Erzeugung zweiter Harmonischer und Summenfrequenzerzeugung, mit Hilfe des unstetigen Galerkin-Verfahrens zu studieren. In diesem Zusammenhang wird demonstriert, wie das optische Signal zweiter Ordnung von Nanoantennen optimiert werden kann. Hierzu wird ein hier erarbeitetes Schema für die Abstimmung des eingestrahten Lichtes angewandt. Zudem führt eine intelligente Wahl des Antennendesigns zu einem optimierten Signal. Im zweiten Teil dieser Arbeit wird das Modell für Raman-aktive Dielektrika behandelt. Genauer wird die nichtlineare Antwort dritter Ordnung für stimulierte Raman-Streuung hergeleitet. Diese wird dazu genutzt, um ein System aus Hilfsdifferentialgleichungen für das unstetige Galerkin-Verfahren zu konstruieren. Die Ergebnisse des erweiterten numerischen Verfahrens werden im Anschluss gezeigt und diskutiert.<br>This thesis is concerned with the theoretical description of nonlinear optical phenomena with regards to the (numerical) discontinuous Galerkin time-domain (DGTD) method. It deals with two different material models: the hydrodynamic model for metals and the model for Raman-active dielectrics. In the first part, we review the hydrodynamic model for metals, where we apply a perturbative approach to the model. We use this approach to calculate the second-order nonlinear optical effects of second-harmonic generation and sum-frequency generation using the DGTD method. In this context, we will see how to optimize the second-order response of plasmonic nanoantennas by applying a deliberate tuning scheme for the optical excitations as well as by choosing an intelligent nanoantenna design. In the second part, we examine the material model for Raman-active dielectrics. In particular, we see how to derive the third-order nonlinear response by which one can describe the process of stimulated Raman scattering. We show how to incorporate this third-order response into the DGTD scheme yielding a novel set of auxiliary differential equations. Finally, we demonstrate the workings of the modified numerical scheme.
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Berg, Sören Lennart [Verfasser], Martin [Akademischer Betreuer] Henk, Martin [Gutachter] Henk, Cifre María A. [Gutachter] Hernández, and Raman [Gutachter] Sanyal. "Lattice points in convex bodies : counting and approximating / Sören Lennart Berg ; Gutachter: Martin Henk, María A. Hernández Cifre, Raman Sanyal ; Betreuer: Martin Henk." Berlin : Technische Universität Berlin, 2018. http://d-nb.info/1174990333/34.

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Books on the topic "Approximation de Raman"

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J, Vanderaar Mark, and United States. National Aeronautics and Space Administration., eds. A planar approximation for the least reliable bit log-likelihood ratio of 8-PSK modulation. National Aeronautics and Space Administration, 1994.

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J, Vanderaar Mark, and United States. National Aeronautics and Space Administration., eds. A planar approximation for the least reliable bit log-likelihood ratio of 8-PSK modulation. National Aeronautics and Space Administration, 1994.

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Chance, Kelly, and Randall V. Martin. Atmospheric Scattering. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199662104.003.0007.

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This chapter describes elastic scattering events, where the wavelength of the scattered light is unchanged from that of the incident light and conservative scattering, scattering without absorption, sometimes closely approximated in clouds. The scattering regime, scattering versus wavelengths and scatterer size are introduced. Polarization in scattering is described by the Stokes vector and the polarization ellipse. Molecular (Rayleigh) scattering is presented and its atmospherically-important inelastic component, Raman scattering (the Ring effect) quantified. Mie scattering for spherical particles is described as is the commonly-used Henyey-Greenstein Mie phase function approximation. Non-spherical scatterers are introduced. The Ångstrom exponent and the expansion of phase functions in Legendre polynomials are described.
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Langen, David. Finite Dimensional Approximations to a raman amplifier model. 2007.

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Schmeisser, Gerhard, Ram Mohapatra, Narendra Kumar Govil, and Mohammed A. Qazi. Progress in Approximation Theory and Applicable Complex Analysis: In Memory of Q.I. Rahman. Springer, 2018.

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Book chapters on the topic "Approximation de Raman"

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"Ellipsoids in the electrostatic approximation." In Principles of Surface-Enhanced Raman Spectroscopy. Elsevier, 2009. http://dx.doi.org/10.1016/b978-0-444-52779-0.00021-0.

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Bloino, J., and M. Biczysko. "IR and Raman Spectroscopies beyond the Harmonic Approximation: The Second-Order Vibrational Perturbation Theory Formulation." In Reference Module in Chemistry, Molecular Sciences and Chemical Engineering. Elsevier, 2015. http://dx.doi.org/10.1016/b978-0-12-409547-2.10931-x.

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De León Portilla, Paulina, Ana Lilia González Ronquillo, and Enrique Sánchez Mora. "Theoretical and Experimental Study on the Functionalization Effect on the SERS Enhancement Factor of SiO2-Ag Composite Films." In Silver Micro-Nanoparticles - Properties, Synthesis, Characterization, and Applications. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97028.

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Herein we addressed a study to determine the enhancement factor (EF) of the Raman signal reached by composite films with two main components, Ag nanoparticles and SiO2 spheres. The study involves the synthesis, structural composition and optical response by using experimental techniques and theoretical-numerical modeling. A colloid with single NPs and agglomerates of them, with a tannic acid layer on its surface, was produced. Separately, porous SiO2 spheres were obtained. A mixture of both, Ag NPs and SiO2 particles was used to produce the films by solvent evaporation method. It is shown that single or agglomerated Ag NPs are preferentially located at the interstices of the SiO2 spheres. Using discrete dipole approximation, the SERS EF has been estimated considering the agglomeration and tannic acid layer. Both, the dielectric spheres and tannic acid layer diminish the electric field intensity and therefore the SERS EF. When a Ag NP with/without a dielectric shell is touching a SiO2 sphere, the EF is as high as 1 × 103, the zones where this value is reached are smaller when the dielectric layer is present. With a cluster of 3 nude Ag NPs surrounded by SiO2 spheres an EF of 2.4 × 103 is obtained.
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Conference papers on the topic "Approximation de Raman"

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Kleiman, Moshe M., Ioseph Gurwich, and Ariel Cohen. "Analytical approximation for multiple Raman-Mie scattering." In SPIE Proceedings, edited by Anatoli G. Borovoi. SPIE, 2005. http://dx.doi.org/10.1117/12.617485.

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Erkintalo, Miro, Goery Genty, Benjamin Wetzel, and John M. Dudley. "Failure of the linear Raman gain approximation in supercontinuum generation." In 12th European Quantum Electronics Conference CLEO EUROPE/EQEC. IEEE, 2011. http://dx.doi.org/10.1109/cleoe.2011.5942820.

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Melnikov, Leonid A., Yulia A. Mazhirina, and Ekaterina I. Romanova. "Gaussian pulse-shape approximation in Raman amplification in optical fibers." In Saratov Fall Meeting 2013, edited by Elina A. Genina, Vladimir L. Derbov, Igor Meglinski, and Valery V. Tuchin. SPIE, 2014. http://dx.doi.org/10.1117/12.2051545.

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Hu, Yanmeng, Xinyu Fang, Yuchenxi Zhang, Tian Yang, Mengmeng Li, and Rushan Chen. "Nested Equivalent Source Approximation for the Simulation of Surface Enhanced Raman Scattering." In 2020 International Conference on Microwave and Millimeter Wave Technology (ICMMT). IEEE, 2020. http://dx.doi.org/10.1109/icmmt49418.2020.9386587.

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Erkintalo, Miro, Goëry Genty, Benjamin Wetzel, and John M. Dudley. "Failure and limitations of linear Raman gain approximation for fiber supercontinuum generation modelling." In SPIE LASE, edited by Konstantin L. Vodopyanov. SPIE, 2011. http://dx.doi.org/10.1117/12.874858.

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Hovhannisyan, Lilit A., and A. Z. Muradyan. "Raman-Nath approximation for atom diffraction in the laser field of counterpropagating waves: instantaneous turn-on of interaction." In International Conference on Laser Physics 2010, edited by Aram V. Papoyan. SPIE, 2010. http://dx.doi.org/10.1117/12.891381.

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Zheng, Yue Bing, Bala Krishna Juluri, and Tony Jun Huang. "Fabrication and Applications of Long-Range Ordered Au Nanodisk Arrays." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-67593.

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Large-scale nanostructure arrays with spatial coherence are useful for many applications. Conventional nanofabrication techniques such as electron beam lithography and focused ion beam lithography are expensive and time-consuming. In this paper, long-range ordered Au nanodisk arrays were fabricated on glass substrates using nanosphere lithography (NSL) combined with reactive ion etching (RIE) techniques. The morphology and size distribution of the Au nanodisks were examined with scanning electron microscopy (SEM) and atomic force microscopy (AFM). The sensitivity of the localized surface plasmon resonance (LSPR) of the Au nanodisk arrays to change in the surroundings’ refractive index was evaluated by integrating the Au nanodisk arrays into microfluidic channels. The measured sensitivity was supported by discrete dipole approximation (DDA) calculations. Further, we designed and fabricated an all-optical plasmonic switch based on the Au nanodisk arrays and photoresponsive liquid crystals (LCs). The high-quality optical properties and high-degree spatial uniformity of the nanodisk arrays, together with simple, low-cost fabrication and easy integration with microfluidic system, suggest tremendous potential in using these nanostructures in many other applications, including biosensing and imaging, surface-enhanced Raman spectroscopy (SERS), and plasmonic tweezers.
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8

Singh, Dhruv, Jayathi Y. Murthy, and Timothy S. Fisher. "Spectral Detail of Phonon Conduction and Scattering in Graphene." In ASME 2011 Pacific Rim Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Systems. ASMEDC, 2011. http://dx.doi.org/10.1115/ipack2011-52243.

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This paper examines the thermodynamic and thermal transport properties of the 2D graphene lattice. The interatomic interactions are modeled using the Tersoff interatomic potential and are used to evaluate phonon dispersion curves, density of states and thermodynamic properties of graphene as functions of temperature. Perturbation theory is applied to calculate the transition probabilities for three-phonon scattering. The matrix elements of the perturbing Hamiltonian are calculated using the anharmonic interatomic force constants obtained from the interatomic potential as well. An algorithm to accurately quantify the contours of energy balance for three-phonon scattering events is presented and applied to calculate the net transition probability from a given phonon mode. Under the linear approximation, the Boltzmann transport equation (BTE) is applied to compute the thermal conductivity of graphene, giving spectral and polarization-resolved information. Predictions of thermal conductivity for a wide range of parameters elucidate the behavior of diffusive phonon transport. The complete spectral detail of selection rules, important phonon scattering pathways, and phonon relaxation times in graphene are provided, contrasting graphene with other materials, along with implications for graphene electronics. We also highlight the specific scattering processes that are important in Raman spectroscopy based measurements of graphene thermal conductivity, and provide a plausible explanation for the observed dependence on laser spot size.
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Close, C. E., M. R. Gleeson, and J. T. Sheridan. "Approximating monomer diffusion in the Raman-Nath regime." In SPIE Photonics Europe, edited by Frank Wyrowski, John T. Sheridan, Jani Tervo, and Youri Meuret. SPIE, 2010. http://dx.doi.org/10.1117/12.854979.

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Berezin, Valentin I., N. V. Bogachev, Vladimir V. Nechaev, and Mikhail D. El'kin. "Comparison of some approximations in calculations of absorption and Raman spectra." In Omsk - DL tentative, edited by Leonid N. Sinitsa. SPIE, 1992. http://dx.doi.org/10.1117/12.131147.

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Reports on the topic "Approximation de Raman"

1

Shore, B. W. Steady-state approximations in Raman excitation equations. Office of Scientific and Technical Information (OSTI), 1987. http://dx.doi.org/10.2172/7128603.

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