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Artykuły w czasopismach na temat "Vibrational Raman Modes"
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Jumeau, Richard, Patrice Bourson, Michel Ferriol, François Lahure, Marc Ponçot i Abdesselam Dahoun. "Identification of LDPE Grades Focusing on Specific CH2 Raman Vibration Modes". International Journal of Spectroscopy 2013 (15.04.2013): 1–6. http://dx.doi.org/10.1155/2013/720598.
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The possibilities of applications of vibrational spectroscopy techniques (Raman spectroscopy) in the analysis and characterization of polymers are more and more used and accurate. In this paper, our purpose is to characterize Low Density Poly(Ethylene) (LDPE) grades by Raman spectroscopy and in particular with CH2 Raman vibration modes. With temperature measurements, we determine different amorphous and crystalline Raman assignments. From these results and on the basis of the evolution of CH2 bending Raman vibration modes, we develop a phenomenological model in correlation with Differential Scanning Calorimetry and in particular with crystalline lamella thickness determination.
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Okamoto, Hiromi, Takakazu Nakabayashi i Mitsuo Tasumi. "Picosecond Anti-Stokes Raman Excitation Profiles as a Method for Investigating Vibrationally Excited Transients". Laser Chemistry 19, nr 1-4 (1.01.1999): 335–41. http://dx.doi.org/10.1155/1999/21312.
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A method for estimating vibrational quantum numbers of vibrationally excited transients in solution is proposed. In this method, we calculate anti-Stokes Raman excitation profiles (REPs) which are characteristic of the initial vibrational states involved in the Raman process, and compare them with observed anti-Stokes intensities. We have applied this method to vibrationally hot molecules of canthaxanthin in the So state and those of trans-stilbene in the S1 state. For canthaxanthin, it has been found that the vibrationally excited transients are for the most part on the ν=1 level of the C═C stretching mode, and that excess vibrational energy is statistically distributed among all intramolecular vibrational modes. As for S1 stilbene, vibrational transients are shown to be mostly on the ν=1 level for two vibrational modes examined, while the excess vibrational energy is probably localised on the olefinic C═C stretching mode.
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Fang, S. L., L. Grigorian, P. C. Eklund, G. Dresselhaus, M. S. Dresselhaus, H. Kawaji i S. Yamanaka. "Raman scattering from vibrational modes inSi46clathrates". Physical Review B 57, nr 13 (1.04.1998): 7686–93. http://dx.doi.org/10.1103/physrevb.57.7686.
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Shakoor, Abdul, Fayyaz Hussain, Najmul Hassan, Abdul Majid, Muhammad Tariq Bhatti i Hassan Siddique. "A density functional theory study of Raman modes of cadmium hexathiohypodiphosphate (CdPS3)". Materials Science-Poland 33, nr 2 (1.06.2015): 286–91. http://dx.doi.org/10.1515/msp-2015-0041.
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AbstractRaman scattering investigations based on density functional theory (DFT) calculations were performed to explore the vibrational modes of a cadmium hexathiohypodiphosphate CdPS3 single crystal. The calculations were performed to obtain the Raman spectra for the cadmium hexathiohypodiphosphate atoms to study the size dependence. Several vibrational modes indicating stretching and bending features related to Cd, S and P atoms were observed. Modifications of the frequency and intensity of different Raman modes with an increase in the number of atoms in CdPS3 were discussed in detail. Hydrogen atoms were added in order to make the closed shell configuration and saturate the CdPS3 as per the requisite for calculating the Raman spectra. This produced some additional modes of vibration related to hydrogen atoms. Band gap and formation energy were also calculated. The results generated are found to be in close agreement with the experimental values.
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Islam, Md Mahfujul, i Fredric Datchi. "Polarized Raman Spectra of α Quartz". International Letters of Chemistry, Physics and Astronomy 56 (lipiec 2015): 91–98. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.56.91.
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The purpose of this experiment was to observe the Raman shift to assign the symmetry character of the obtained vibrational modes of α-quartz (which has 9 atom per unit cell) using the selection rules for Raman Effect. We observed the Raman spectra varying the polarization of the incoming beam and the orientation of the crystal. And we used monochromatic radiation of argon laser of wavelength 540 nm for our Raman spectroscopy. We observed the intensity of light rotating the polarizer to vertical position from its horizontal position with respect to the plane of the optical table where the laser is placed and measured the Raman spectra over an energy from 50 to 1250 cm-1 using the laser power of 1W and an acquisition time of 10 sec. averaging over 2 acquisitions. From our experiment we can see that here is 4symmetry for A1 which is predicted on our vibrational modes. However for E symmetry mode we have observed 14 vibrational modes but as E is doubly degenerate there should be 16 vibrational modes on the Raman active modes in the α quartz, as we can see that there are two vibration missing ,it happens may be due to noise on the surroundings. We got different peaks due to the different intensities and the different orientation of the laser beam hitting the sample on different angle. The different intensities of the peaks for the different orientation might be due to the laser beam hitting the samples at different angles due to differences in the orientation of the surfaces. We also found that the biggest amount of the re-radiated light was vibrating horizontally, i.e. in the same direction as the laser beam hitting the sample.
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Islam, Md Mahfujul, i Fredric Datchi. "Polarized Raman Spectra of α Quartz". International Letters of Chemistry, Physics and Astronomy 56 (21.07.2015): 91–98. http://dx.doi.org/10.56431/p-k754hp.
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The purpose of this experiment was to observe the Raman shift to assign the symmetry character of the obtained vibrational modes of α-quartz (which has 9 atom per unit cell) using the selection rules for Raman Effect. We observed the Raman spectra varying the polarization of the incoming beam and the orientation of the crystal. And we used monochromatic radiation of argon laser of wavelength 540 nm for our Raman spectroscopy. We observed the intensity of light rotating the polarizer to vertical position from its horizontal position with respect to the plane of the optical table where the laser is placed and measured the Raman spectra over an energy from 50 to 1250 cm-1 using the laser power of 1W and an acquisition time of 10 sec. averaging over 2 acquisitions. From our experiment we can see that here is 4symmetry for A1 which is predicted on our vibrational modes. However for E symmetry mode we have observed 14 vibrational modes but as E is doubly degenerate there should be 16 vibrational modes on the Raman active modes in the α quartz, as we can see that there are two vibration missing ,it happens may be due to noise on the surroundings. We got different peaks due to the different intensities and the different orientation of the laser beam hitting the sample on different angle. The different intensities of the peaks for the different orientation might be due to the laser beam hitting the samples at different angles due to differences in the orientation of the surfaces. We also found that the biggest amount of the re-radiated light was vibrating horizontally, i.e. in the same direction as the laser beam hitting the sample.
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Nakabayashi, Takakazu, Hiromi Okamoto i Mitsuo Tasumi. "Pump- And Probe-Wavelength Dependencies of Picosecond Anti-Stokes Raman Spectrum of Trans-Stilbene in the S1 State". Laser Chemistry 19, nr 1-4 (1.01.1999): 75–78. http://dx.doi.org/10.1155/1999/10475.
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Vibrational relaxation dynamics of trans-stilbene in the S1 state immediately after photoexcitation is studied by picosecond time-resolved anti-Stokes Raman spectroscopy with several pump and probe wavelengths. Pump-wavelength dependence of the anti- Stokes spectrum indicates that, when pump photons with high excess energy (≈5200cm-1) are used, the anti-Stokes Raman bands at 0 ps delay time arise from vibrationally excited transients with excess vibrational energy not thermally distributed in the molecule. Probe-wavelength dependence suggests that the vibrationally excited transients at 0 ps are mostly on the lowest excited vibrational levels, as far as the olefinic C═C stretching and the C–Ph stretching modes are concerned. The vibrational relaxation process of S1trans-stilbene is discussed on the basis of the observed results.
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Коrnienko, N. E., i O. L. Pavlenko. "Multiple Fermi Resonances in Liquid Benzene". Ukrainian Journal of Physics 65, nr 6 (9.06.2020): 480. http://dx.doi.org/10.15407/ujpe65.6.480.
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A number of coupled Fermi vibrational resonances (FRs) in liquid benzene from a multitude of them are systematically studied. The spectral structure of the vibrational bands in the IR absorption and Raman scattering spectra are determined by their numerical decomposition into individual components. The complication of vibrational resonances with an increase in their order is due to the overlapping of FRs and the appearance of additional resonant vibrational modes. To clarify the identification of the vibrations of the benzene FR v1+v6, v8 and the correction of the frequencies of a number of inactive vibrations, including v13(E1u), the experimental results are compared to the data obtained by quantum-chemical calculations. With regard for the collective-wave properties of vibrational modes in the benzene liquid state, we propose a new content of the analysis of FRs. It should include the study of 1) the intensity changes for various spectral components in the IR absorption and Raman scattering for FR vibrational bands of various orders, 2) half-widths δv of the bands, and 3) anharmonic shifts ΔvA for various components in the vibrational bands of FRs.
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Vaithianathan, V., R. Kesavamoorthy, C. V. Kannan, P. Santhanaraghavan i P. Ramasamy. "Raman study of gaseous bubble inclusions in bismuth germanate and bismuth germanium silicon oxide single crystals". Journal of Materials Research 18, nr 4 (kwiecień 2003): 762–67. http://dx.doi.org/10.1557/jmr.2003.0105.
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Gaseous bubble inclusions in bismuth germanate (BGO) and bismuth germanium silicon oxide (BGSO) crystals were studied by means of Raman spectroscopy at room temperature. Their Raman spectra in the range from 60 to 70 cm−1 showed three peaks for the rotational Raman modes of O2 and N2. Vibrational Raman modes of O2 and N2 were also recorded for BGO and BGSO crystals. It was found that all the rotational and vibrational modes were blue shifted from those of free molecules due to the hydrostatic pressure in the bubbles. Internal pressure in the bubbles was estimated from the rotational and vibrational Raman mode frequencies. O2 gas pressure in the bubble was estimated as 140 GPa, and N2 gas pressure, as 31 GPa. The pressure coefficient of the vibrational mode frequency of O2 (0.368 cm−1/GPa for O2 vibrational mode of 1580 cm−1) and N2 (0.322 cm−1/GPa for N2 vibrational mode of 2331 cm−1) was also obtained from the blue shift and the calculated bubble pressure.
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Srinivasan, S., i V. Renganayaki. "Computational Studies of Vibration Spectra and Thermodynamic Properties of Metformin Using HF, DFT Methods". Material Science Research India 8, nr 1 (25.06.2011): 165–72. http://dx.doi.org/10.13005/msri/080124.
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The molecular vibrations of metformin, one of the important anti-diabetic drugs to treat Non Insulin Dependent Diabetes Mellitus (NIDDM) have been investigated at room temperature by Fourier transform infrared (FTIR) and Fourier transform Raman (FTR) spectroscopies. The solid phase FTIR and FT-Raman spectra of the title compound have been recorded in the regions 4000-400 and 3500-250 cm-1. A satisfactory band assignment has been made on the fundamental modes of vibration. Employing the ab - initio Hatree –Fock (HF) and Density Function Theory (DFT) methods, the theoretical vibrational frequencies and geometry parameters like bond lengths, bond angles etc have been calculated and compared with the experimental values. HF and DFT calculations were performed using the standard B3LYP/6-31G** method and basis set combination. Optimized geometries were obtained using the global optimization procedure. Theoretical investigations of harmonic vibrational frequencies and thermodynamic properties viz. the zero point vibrational energy (ZPVE), entropy, heat capacity have been carried out. It has been found that both methods gave consistent data for geometric parameters, but DFT yielded vibrational frequencies much closer to the experimental values.
Rozprawy doktorskie na temat "Vibrational Raman Modes"
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Simonelli, Danielle Marie. "Probing vibrational modes of ammonia with the nonlinear optical technique sum frequency generation /". Thesis, Connect to Dissertations & Theses @ Tufts University, 2000.
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Thesis (Ph.D.)--Tufts University, 2000.Adviser: Mary Jane Shultz. Submitted to the Dept. of Chemistry. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Wachsmann-Hogiu, Sebastian. "Vibronic coupling and ultrafast electron transfer studied by picosecond time resolved resonance Raman and CARS spectroscopy". Doctoral thesis, [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=960830898.
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Quick, Martin. "Ultrafast photophysical processes in electronically excited flavin and beta-carotene". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17523.
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Die Kombination aus Breit-Band Spektroskopie-Methoden ermöglicht eine umfassende Einsicht in das elektronische System von Molekülen im angeregten Zustand. Am Beispiel des Riboflavin in saurer Umgebung wird der Protonen-Transfer aus der Lösung auf den Chromophor mittels transienter Absorption und -Fluoreszenz im S1-Zustand beobachtet. Mittels transienter Absorption- und Femtosekunden-stimulierter Raman-Spektroskopie wird der Populationstransfer in den elektronischen Grundzustand im beta-Karotin verfolgt und charakterisiert werden.The combination of broadband spectroscopic methods allows a comprehensive view of the electronic system of molecules in the excited state. On riboflavin in acidic environment the proton-transfer is observed with transient absorption and -flurescence in the S1-state. With transient absorption and femtosecond-stimulated Raman-spectroscopy the population transfer into the electronic ground-state is followed and characterized.
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Al, Majzoub Al Sabbagh Maryam. "Vibrations polaires de basse fréquence de composés ferroélectriques et relation avec leurs propriétés diélectriques géantes : relaxeurs et nanocéramiques". Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT253.
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Les matériaux ferroélectriques possédant des propriétés diélectriques géantes font l’objet d’une grande attention scientifique, en grande partie à cause de leur utilisation et potentialités futures dans les dispositifs technologiques, en particulier en microélectronique. L’intérêt de ce travail porte sur l’étude des propriétés vibrationnelles de deux systèmes modèles : le relaxeur PbMg1/3Nb2/3O3 (PMN) monocristallin, et des nano-céramiques de SrTiO3 de tailles de grains contrôlées. Les travaux ont été menés essentiellement par une technique non-linéaire optique originale, la diffusion hyper-Raman (HR) de la lumière, et une attention particulière a été portée aux vibrations de basse fréquence. Des modèles structuraux pu être développés pour relier les signatures spectrales aux propriétés diélectriques de ses systèmes.Dans un premier temps, la spectroscopie hyper-Raman a été poussée à ses limites et a permis d’aboutir à une description convaincante de la dynamique de la polarisation électrique de PMN dans le domaine THz et ce, sur une gamme de température couvrant l’ensemble des différents états relaxeurs. L’hypothèse très répandue mettant en avant l’existence de deux modes mous polaires a ainsi pu être exclue. Les anomalies spectrales à haute température s’expliquent par un couplage entre un mode mou ferroélectrique unique et une vibration non-polaire dont le comportement est indépendant de la température. En refroidissant, l’éclatement du mode mou ferroélectrique révèle la formation d’une anisotropie polaire en dessous de 400-500 K. L’ensemble des modifications spectrales a été capturé dans un modèle simple qui rend également compte de la dépendance en température de la permittivité diélectrique.Dans une seconde partie, les expériences hyper-Raman ont été menées dans deux céramiques de titanate de strontium (SrTiO3) possédant des tailles de grains différentes, 80 nm et 150 nm. L’avantage de la diffusion hyper-Raman pour cette étude est sa propension à sonder les réponses spectrales individuelles du coeur et de la coquille des grains, alors que les techniques usuelles d’absorption infrarouge sondent un milieu effectif moyen. L’analyse spectrale révèle des propriétés de grains identiques dans les deux céramiques : même valeur et même dépendance en température de l’épaisseur de la coquille entourant le cœur, et permittivités diélectriques de cœur ainsi que de coquille identiques dans les deux cas. Un modèle structural reliant les propriétés vibrationnelles et la permittivité diélectrique effective confirme l’existence de deux coquilles entourant le cœur des grains.Ces travaux montrent par ailleurs qu’entre 150 nm et 80 nm, la diminution des propriétés diélectriques est principalement liée au rapport des volumes entre le cœur (haute permittivité) et les coquilles (basses permittivités)Materials that exhibit giant dielectric properties have received a huge amount of attention from the scientific and industrial communities due to their potentialities and applications in technological devices, in particular for microelectronic applications. In this work, we are interested in studying the vibrational properties of a prototypical relaxor single crystal, PbMg1/3Nb2/3O3 (PMN), as well as nanoceramics of SrTiO3 (STO) with controlled grain sizes. The experiments have been mostly performed by hyper-Raman scattering (HRS), an original non-linear inelastic light scattering spectroscopy. Special attention was devoted to low frequency vibrations, and structural models were developed to relate the vibrational signatures to the giant dielectric responses of these systems.HRS spectroscopy was pushed towards its limit and provided a comprehensive picture of the polarization dynamics of PMN in the THz-range within the whole temperature sequence of its characteristic relaxor states. The widespread hypothesis of two paraelectric soft modes is convincingly excluded. The observation of the split ferroelectric mode reveals the local anisotropy below about 400 K. In contrast, the spectral anomalies observed at higher temperatures are explained as due to avoided crossing of the primary polar soft mode with a temperature-independent, non-polar spectral feature. The temperature changes of the vibrational modes involved in the measured fluctuation spectra of PMN were captured in a simple model that accounts for the temperature dependence of the dielectric permittivity as well.On the other hand, HRS experiments were carried-out on STO single crystal and nano-ceramics of different grain sizes, 80nm and 150nm. Contrary to IR-absorption which gives an effective spectral response of the core and the shell(s) constituting the grains, we show that hyper-Raman provides information of the individual core and shell responses. The spectral analysis reveals that except from their volume, the grains in the two ceramics exhibit very similar structures and properties: same value and temperature dependence of the shell thickness surrounding the core, and same dielectric response of the core as well as of the shell in the two samples. Structural models relating the vibrational properties to the effective dielectric permittivity were developed, and confirm that in STO the grains are composed by one core and two surrounding shells. We demonstrate that between 150 nm and 80 nm the decrease of the effective dielectric permittivity with grain size relates mostly to a change in core and shell volume fraction
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Von, Laue Lukas. "Transferts de protons par effet tunnel dans l'acide benzoique : le rôle des vibrations moléculaires". Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10060.
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Une description quantitative des transferts de protons inter- et intramoleculaires, qui sont parmi les reactions chimiques les plus fondamentales, demande une connaissance de la surface d'energie potentielle. Le present travail contribue a la caracterisation de cette surface pour un systeme modele, le monocristal d'acide benzoique. Proche des positions d'equilibre, la spectroscopie vibrationnelle apporte des informations, tandis que la barriere de potentiel est caracterisee par des mesures d'effet tunnel. Ces mesures, par spectroscopie optique (raman, absorption, emission) et diffusion quasi-elastique de neutrons, sont faites en combinaison avec des substitutions isotopiques (#1#8o) et sous pression hydrostatique. Une nouvelle methode permettant de calculer la dynamique sur la surface d'energie potentielle multidimensionnelle est presentee. Elle repose sur une approche perturbative qui utilise la technique des instantons et evite la reduction habituelle a 2 ou 3 dimensions. Cette theorie peut etre appliquee dans le but d'evaluer l'effet tunnel de facon generale : inversion de l'ammoniac, rotation des groupements methyles, etc. . Pour les transferts de protons dans des dimeres d'acides carboxyliques, on fait une comparaison avec les resultats experimentaux.
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Sirotkin, Sergey. "Low frequency modes from small nanoparticles (metal nanocrystals) to large nanospheres (viruses) : an inelastic light scattering study". Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00847063.
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The doctoral thesis "Low frequency modes from small nanoparticles (metal nanocrystals) to large nanospheres (viruses): an inelastic light scattering study" is dedicated to investigations of the acoustic properties of different nano-objects : small metal nanoparticles and nanocrystals (D < 30 nm) and large colloid/viral particles (D _ 200 nm). Inelastic light Raman/Brillouin scattering is used as the main research tool to probe the nanoparticle vibrations and to determine their elastic and mechanical parameters. In the first chapter, the well developed theory of elasticity is used to perform a qualitative and nomenclatural analysis of solid sphere vibrations ; several theoretical models allowing to describe the nanoparticle vibrational behavior within a surrounding medium and how the eigenvibrations are modified due to inner crystalline elastic anisotropy are discussed. The second chapter is dedicated to the description of the physics of inelastic light scattering which derives from the fluctuations of the polarizability induced by vibrations. Two types of inelastic light scattering are described : Brillouin scattering which results from the coupling of incident light (photon) with acoustic propagative waves (phonon) in a bulk substance and Raman scattering which is a result of the interaction between an incident photon and localized vibrations, hence nanoparticle vibrations in the present study. As essential in our study, the detailed description and principles of operation of the spectroscopic tools (tandem Fabry-Perot) used to perform these very low frequency inelastic light scattering spectroscopies (between 3 and 300 GHz typically) are given. The third chapter focuses on the study of low frequency modes from small metallic nanoparticles. Three systems are investigated : AuAg and Cu nanoparticles embedded in a vitreous matrix and Au nanocrystals deposited on a surface. The AuAg system allowed to study a notably rich Raman spectrum featuring contributions from fundamental modes and high order harmonics. The experimental data were found to compare rather well with theoretical predictions, thereby providing more insight into the essential ingredients of Raman scattering from nanoparticle modes. The study of deposited Au nanocrystals allowed characterizing the effect of nanocrystalline quality which results in a partial lifting of degeneracy of the nanoparticle modes due to elastic anisotropy. Investigating the wavelength dependence of the Raman spectrum allows a differentiation between single nanocrystals and multiply twinned nanoparticles. Both embedment effects and nanocrystallinity effects are integrated in the study of Cu nanoparticles grown in a glass matrix, where the influence of annealing conditions on the produced nanoparticles was investigated. It was shown that different annealing temperatures [...] result in very different low frequency Raman profiles. [...] The forth chapter reports on the exploration of the possible use of the low frequency inelastic light scattering probe in the characterization of large viruses, as illustrated in the third chapter for small nanoparticles. In order to address the change of the light selection rules as the wavelength of the exciting light becomes comparable to the size of the nanoparticles, the behaviors of the viruses are compared to those of polymer colloids. Ultra Small Angle X-ray Scattering and Atomic Force Microscopy are used to first ensure the comparableness of viruses and polystyrene colloids in terms morphologies. On the basis of the inelastic light scattering data obtained for PS colloids [...], we discuss the difficult interpretation in termsof eigenmodes of the virus counterparts.
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Kremer, David. "Sur des transitions Raman faiblement permises dans l’hexafluorure de soufre : spectroscopie de haute sensibilité de bandes harmoniques et induites". Angers, 2014. https://tel.archives-ouvertes.fr/tel-01112199.
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Le dioxyde de carbone est certes le gaz à effet de serre le plus connu du grand public. Mais il existe dans l’atmosphère terrestre des gaz peu médiatisés, présents en infimes quantités, dont la dangerosité potentielle n’est pas moindre. Ainsi, la molécule de SF6 a un pouvoir de forçage radiatif environ 24 000 fois supérieur à celui du CO2. D’origine anthropogénique, utilisé majoritairement comme isolant électrique, ce gaz voit depuis quelques années sa concentration dans l’atmosphère augmenter au taux alarmant de 8% par an. Ces données expliquent pourquoi l’hexafluorure de soufre est l’une des cibles de la lutte contre le réchauffement climatique dans le protocole de Kyoto et justifient le regain d’intérêt qui lui est porté dans le domaine académique. Dans cette thèse, nous avons réalisé une étude à la fois expérimentale et théorique de certaines transitions faiblement permises en spectroscopie Raman relatives à l’hexafluorure de soufre. Les transitions étudiées sont d’une part les harmoniques 2ν3 et 2ν5 de la molécule, toutes deux actives en Raman en raison d’anharmonicités électriques ou mécaniques dans la molécule isolée. Le fait que les vibrations ν3 et ν5 sont respectivement considérées comme les plus représentatives des modes d’étirement et de fléchissement de SF6 fût une motivation importante dans ce choix. Une étude expérimentale de la bande ν3 « induite par les collisions », correspondant aux paires SF6−SF6, a d’autre part été menée et s’ensuit dans ce rapport. D’autres études relatives aux molécules isolées sont également présentées. Les expériences ont été réalisées avec un montage Raman artisanal de haute sensibilité et au moyen d’un protocole particulièrement strict, perpétuant un savoir-faire développé au sein d’une équipe reconnue pour sa capacité à détecter et analyser des flux lumineux de très faible intensitéOf all greenhouse gases (GHGs), carbon dioxide is definitely the most notorious to the wide public. Yet, there are GHGs present in much more tiny amounts in the Earth’s atmosphere, whose destructive power is substantial albeit less widely publicized. SF6 is a GHG considered as a dangerous pollutant of our atmosphere for that its global warming potential (GWP) amounts to about 24 000 times the GWP of CO2. Of anthropogenic origin, primarily owing to the industry of electrical insulators, the emissions of that gas are presently being increased at the alarming rate of 8% per year. These observations fully justify why sulfur hexafluoride currently tends to become a serious competitor of carbon dioxide and why its emissions are targeted in the Kyoto protocol. Here we present a study, both experimental and theoretical, of certain weakly-allowed Raman-scattering transitions related to gaseous SF6. These are either transitions in the isolated molecules or collision-induced transitions within pairs of molecules. Specifically, the overtones 2ν3 and 2ν5 of SF6 were studied, which both are Raman-active because of electrical or mechanical anharmonicity in the isolated molecule. This choice was prompted by the fact that ν3 and ν5 are the molecule’s most representative stretching and bending vibrations, respectively. It follows an experimental study of the collision-induced SF6−SF6 transition at the position of the ν3 vibration, as well as other transitions related to the isolated molecule. The high-sensitivity Raman equipment we have used and the stiff protocol we have followed regarding detection, acquisition, processing and analysis of spectra are part of a long experience and knowhow within a research group recognized for its capacity to capture and analyze extremely weak light signals
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Sourovtsev, Nikolay. "Modes de relaxation et de vibration basse fréquence dans les polymères vitreux : étude par diffusion Raman". Lyon 1, 1996. http://www.theses.fr/1996LYO10105.
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La diffusion inelastique basse frequence a ete etudiee experimentalement dans plusieurs verres polymeriques: poly(methyle methacrylate) (pmma), polycarbonate (pc) et poly(styrene) (ps). Les resultats suivants ont ete obtenues: 1). Il est montre que le temps de relaxation est soit independant (pc, ps), soit tres peu dependant (pmma) de la temperature. 2). Le nombre d'unites relaxantes, responsables de la diffusion quasi-elastique, augmente fortement avec la temperature. 3). Il est trouve que l'augmentation du nombre de monomeres dans le verre de pmma, apres traitement thermique, est suivi d'une augmentation de la diffusion quasi-elastique. Il est montre qu'il existe une relation lineaire entre l'intensite de la diffusion quasi-elastique et la concentration en monomeres. 4). Un modele interpretant le comportement experimental de la diffusion quasi-elastique est propose. Il utilise le concept de volume libre
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Stephanidis, Bruno. "Modes de vibration de nano-objets : des nanoparticules métalliques aux virus biologiques". Phd thesis, Université Claude Bernard - Lyon I, 2008. http://tel.archives-ouvertes.fr/tel-00294763.
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Comparée à leur structure généralement très bien caractérisée, la dynamique collective des nano-objets est assez mal connue. En une vingtaine d'années, la diffusion inélastique de lumière est devenue un outil puissant dans l'étude de la dynamique des nano-objets.Ce travail traite de la transposition de cette technique habituellement appliquée à l'étude des modes propres de vibration de nanoparticules solides à la recherche de modes similaires chez leur équivalent biologique, les virus.
Nous revenons dans un premier temps sur les expériences Brillouin (ou Raman basse fréquence) sur des verres dopés à l'or et discutons de l'utilité du tandem Fabry-Pérot en particulier par l'apport de la haute résolution dans la détection des levées de dégénérescence associées à l'anisotropie des paramètres élastiques des nanoparticules d'or facettées.
La deuxième partie de ce travail est consacrée à la recherche de modes de vibration d'ensemble sur des virus à morphologie sphérique à travers l'étude de différents types d'échantillons : solutions, couches bidimensionnelles et cristaux tridimensionnels de virus. Cette partie rend compte d'une première détermination des constantes élastiques globales d'un cristal de phytovirus. Alors que pour les virus de petite taille (15-30nm) aucune preuve indiscutable de l'existence d'un mode de vibration de virus n'a pu être trouvée, pour un virus de plus grande taille (environ 200nm), un signal s'apparentant à un mode de vibration de virus a été observé.
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Breitenstein, Jacques. "Etude par spectroscopie raman de conducteurs organiques unidimensionnels, (tmtsf) 2x". Paris 7, 1988. http://www.theses.fr/1988PA077179.
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Trois sels de bechgaard (tmtsf)::(2)x (ou x=pf::(6), clo::(4) et reo::(4)) sont etudies dans des conditions de double resonance raman. Determination des modes de vibration donnant des termes importants dans ces conditions de double resonance. Mise en evidence de l'existence des modes rendus actifs grace a un forty couplage avec des transferts dynamiques de charge intermoleculaires ou intramoleculaires. Les informations importantes concernant ce couplage de modes internes - transferts de charge sont obtenues lors de l'etude de la transition metal - isolant et de la mise en ordre a 2k::(f) des anions dans (tmtsf)::(2)reo::(4). Observation des modes mettant en jeu des transferts intradimeres
Książki na temat "Vibrational Raman Modes"
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ZnO bao mo zhi bei ji qi guang, dian xing neng yan jiu. Shanghai Shi: Shanghai da xue chu ban she, 2010.
Znajdź pełny tekst źródłaCzęści książek na temat "Vibrational Raman Modes"
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Carpinteri, Alberto, Giuseppe Lacidogna, Andrea Bassani i Gianfranco Piana. "Global Vibrational Modes in Proteins: Raman Spectroscopy and Numerical Modeling". W Mechanics of Biological Systems, Materials and other topics in Experimental and Applied Mechanics, Volume 4, 15–18. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-63552-1_3.
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Kobayashi, Takayoshi, Masakatsu Hirasawa, Yuzo Sakazaki i Hiroki Hane. "Amplitude spectra of molecular vibration modes in phthalocyanine: comparison with Raman excitation profile". W Springer Series in Chemical Physics, 371–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/3-540-27213-5_113.
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Iwata, K., i H. Hamaguchi. "Picosecond Time-Resolved Raman Observation of the Mode-Dependent Vibrational Dynamics in S1 Trans-Stilbene". W Springer Proceedings in Physics, 85–88. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-85060-8_21.
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Fillaux, Francois. "Introduction to Vibrational Spectroscopy — From the Normal Mode to the Local Mode: Infrared, Raman and Inelastic Neutron Scattering". W The Enzyme Catalysis Process, 79–91. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4757-1607-8_7.
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Kojima, Seiji. "Terahertz Spectroscopy in Advanced Materials Science". W Trends in Terahertz Technology [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.110850.
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Materials science is the interdisciplinary field to study material properties and their functionality on the basis of physics, chemistry, metallurgy, and mineralogy. Vibrational spectroscopy such as infrared spectroscopy and Raman spectroscopy is a powerful tool to investigate characteristic atomic vibrations. Especially, in the terahertz frequency range, vibrational modes are related to collective atomic vibrations reflecting interatomic/molecular interactions, characteristic units, and medium range order. Recent progress of terahertz vibrational spectroscopy using terahertz-time-domain spectroscopy, terahertz time-domain spectroscopic ellipsometry, and far-infrared spectroscopy is reviewed in advanced materials science on glassy and crystalline pharmaceuticals, ferroelectrics, and polar metallic materials. Using the terahertz spectra, phonons, polaritons, and conduction electrons of these materials are discussed.
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Autschbach, Jochen. "Quantized Vibrational Motion". W Quantum Theory for Chemical Applications, 281–305. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780190920807.003.0014.
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The harmonic oscillator of chapter 2 is visited again, now in its quantum theoretical version. The solution of the Schrodinger equation (SE) is shown step-by step, as it features steps that are very similar to those used in solving the equations for the angular momentum and hydrogen-like orbitals in later chapters. The Morse oscillator has a potential function that is much more representative of the vibrations of atoms in molecules as the harmonic potential. The solutions of the harmonic and Morse oscillator are compared. It is then shown how nuclear vibrations in poly-atomic molecules are treated at the harmonic level. This requires the separation of internal degrees of freedom from the overall translation and rotation of a molecule, leading to the normal modes. The chapter also discusses basic aspects of vibrational spectroscopy and the selection rules of infrared and Raman vibrational spectroscopy.
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Kumar, Samir, Prabhat Kumar, Anamika Das i Chandra Shakher Pathak. "Surface-Enhanced Raman Scattering: Introduction and Applications". W Recent Advances in Nanophotonics - Fundamentals and Applications. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.92614.
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Scattering of light by molecules can be elastic, Rayleigh scattering, or inelastic, Raman scattering. In the elastic scattering, the photon’s energy and the state of the molecule after the scattering events are unchanged. Hence, Rayleigh scattered light does not contain much information on the structure of molecular states. In inelastic scattering, the frequency of monochromatic light changes upon interaction with the vibrational states, or modes, of a molecule. With the advancement in the laser sources, better and compact spectrometers, detectors, and optics Raman spectroscopy have developed as a highly sensitive technique to probe structural details of a complex molecular structure. However, the low scattering cross section (10−31) of Raman scattering has limited the applications of the conventional Raman spectroscopy. With the discovery of surface-enhanced Raman scattering (SERS) in 1973 by Martin Fleischmann, the interest of the research community in Raman spectroscopy as an analytical method has been revived. This chapter aims to familiarize the readers with the basics of Raman scattering phenomenon and SERS. This chapter will also discuss the latest developments in the SERS and its applications in various fields.
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Kojima, Seiji. "Low Energy Excitations in Borate Glass". W Characteristics and Applications of Boron [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106650.
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The boson peak in the terahertz range is the low-energy excitations in glasses and disordered crystals. It is related to the excess part of the vibrational density of states. Borate glass is one of the typical network oxide glasses with covalent bonds and belongs to the strong type of glass formers. Alkali metal ions are well-known modifiers of the borate glass network and control various properties. The alkali metal effects are reviewed on basic physical properties such as elastic constants, density, and vibration modes in relation to the variation of structural units in a modified borate glass network. The alkali effect on a boson peak is discussed on the basis of experimental results of neutron inelastic scattering, neutron diffraction, Raman scattering, and heat capacity at low temperatures. The correlation is discussed between the boson peak frequency, the peak temperature of excess heat capacity, and shear modulus. The static and dynamical correlation lengths are also discussed.
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Choudhary, Sumitra, Vikas Sharma, Abhishek Sharma, Ajay Kumar i Parveen Kumar. "Analyzing the Properties of Zinc Oxide (ZnO) Thin Film Grown on Silicon (Si) Substrate, ZnO/Si Using RF Magnetron Sputtering Approach". W Modeling, Characterization, and Processing of Smart Materials, 297–308. IGI Global, 2023. http://dx.doi.org/10.4018/978-1-6684-9224-6.ch014.
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In this work, ZnO single layer thin film of 100 nm is deposited on a Si substrate using RF magnetron sputtering. Base pressure of 1.0×10−5 mbar, RF power of 100W at Ar flow 15 sccm and room temperature were process parameters. The average crystallite size of ZnO layer, deposited on Si substrate, using Scherrer's formula was 108.16 nm. XRD verifies the crystalline nature of ZnO with various peaks at (002), (101) and (103) planes. Using AFM technique, ZnO had an Average Surface Roughness (Ra) of 2.75 nm and RMS roughness (Rq) of 3.70 nm. From Hall measurements at room temperature, the authors determined that ZnO is a n-type semiconductor having a resistivity of 1 to 100 Ωcm. The layer's sheet resistance was 7.05×103 Ω/sq, and its resistivity was 7.05×10−2 Ωcm. The Raman spectra analysis confirmed the presence of Raman active modes in the sample, confirming the existence of certain vibrational modes. In PL spectra, an emission peak was observed at 380.30 nm, which closely resembled pure ZnO. These results collectively shows that the ZnO/Si thin films grown on Si demonstrated excellent quality.
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Wong, Patrick T. T. "Correlation Field Splitting of Chain Vibrations: Structure and Dynamics in Lipid Bilayers and Biomembranes". W High Pressure Effects in Molecular Biophysics and Enzymology. Oxford University Press, 1996. http://dx.doi.org/10.1093/oso/9780195097221.003.0020.
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Pressure-tuning vibrational spectroscopy was first introduced to the study of structural and dynamic properties in biological systems from our laboratory about one decade ago. One of our efforts has been the search for spectral features and their pressure dependencies related to the structural and dynamic properties in biological systems. Pressure-induced correlation field splitting of the vibrational modes of methylene chains is one of the parameters that has been applied to monitor various structural and dynamic properties of a wide range of aqueous lipid bilayers and biomembranes in our laboratory. Correlation field splitting of the vibrational modes of the methylene chains in lipid bilayers is the result of vibrational coupling interactions among the ordered methylene chains with different site symmetry in the two-dimensional matrix. However, the basic theory and the characteristics of these interchain interactions in lipid bilayers still needed to be established. It was unknown whether the interchain interactions that result in the correlation field splitting take place within each lipid molecule or between neighboring molecules in the lamellar bilayers. The relative contributions of 'intramolecular and intermolecular interchain interactions to the correlation field splitting, and the effects of the long-range interchain interactions and interdigitation on the correlation field splitting, were also unknown. These problems have been resolved recently and are addressed in this chapter. Our laboratory has pioneered the study of structural and dynamic properties of biological systems by means of pressure-tuning vibrational spectroscopy (Wong et al., 1982). It is now well recognized that this spectroscopic technique is one of the most powerful physical methods for the study of biological and biomedical phenomena at the molecular level with enhanced resolution (Wong, 1984, 1987a, 1987b, 1987c, 1993). The biological systems we have studied by this method include not only various aqueous biomolecular assemblies but also whole cells and intact biological tissues (Rigas et al, 1990; Wong, 1984, 1987b, 1987c, 1993; Wong et al., 1991a, 1991b, 1993). We have found that the pressure-induced changes in many spectral features and parameters in both FTIR and Raman spectra of biological systems result from modifications in structure and dynamics at the molecular level.
Streszczenia konferencji na temat "Vibrational Raman Modes"
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Wang, H., F. D. Medina, Y. D. Zhou i Q. N. Zhang. "Internal vibrational modes and anharmonic effects in ZnWO4 single crystals". W OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.wp2.
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The temperature dependence of polarized Raman spectra from single crystals of ZnWO4, which is a promising scintillation material, are reported. Among the eighteen Raman-active modes, all six internal vibrational modes resulting from the WO6 octahedran are tentatively assigned, we believe for the first time. Based on Raman spectra in the temperature range from 14 K to room temperature, anharmonic effects in ZnWO4, which are presented here, again we believe for the first time, are discussed.
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Hasan, M. M., M. R. Islam, N. F. Chen i M. Yamada. "Vibrational modes in GaxMn1−xSb studied by Raman spectroscopy". W 2008 International Conference on Electrical and Computer Engineering. IEEE, 2008. http://dx.doi.org/10.1109/icece.2008.4769323.
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Tanimura, Yoshitaka. "The 5th- and 7th-order 2D Raman spectroscopy for intramolecular vibrational modes". W International symposium on two-dimensional correlation spectroscopy. AIP, 2000. http://dx.doi.org/10.1063/1.1302858.
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Kwok, Alfred S., i Richard K. Chang. "Fluorescence Seeding of Stimulated Raman Scattering in Microdroplets". W Nonlinear Optics. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/nlo.1992.fb6.
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Simulated Raman scattering (SRS), in the absence of external seeding, builds up from spontaneous Raman noise. When the pump-laser pulsewidth is much longer than the dephasing time of the vibrational relaxation, the SRS spectrum is dominated by the vibrational mode with the maximum Raman gain. The depletion of the input-laser intensity by the SRS-buildup of the Raman mode with the largest gain prevents the SRS-buildup of other Raman modes with weaker gain. Selective feedback in a two-mirror resonator geometry was used to enhance the growth of SRS of the weaker 801 cm1 mode of cyclohexane in an optical cell by lowering the feedback for the strong 2929 cm–1 mode. In a Raman gain experiment, a Raman amplifier is used to amplify a weak seeding beam generated by a Raman oscillator or a tunable laser.
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Andriesh, A. M. "Infrared vibrational modes and Raman scattering in CuAlS2, CuAlSe2, and CuAlxGa1-xSe2 crystals". W 17th Congress of the International Commission for Optics: Optics for Science and New Technology. SPIE, 1996. http://dx.doi.org/10.1117/12.2299051.
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Chronister, E. L., i R. A. Crowell. "Vibrational Exciton Decay in Uranyl Crystals by Picosecond Coherent Raman: Energy Bottlenecks and High Order Relaxation Mechanisms". W International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/up.1990.pdp23.
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Anharmonicity in the crystal potential leads to phonon interactions which result in vibrational relaxation and dephasing. For many crystal systems a satisfactory description of vibrational relaxation is obtained by considering the first anharmonic correction to the crystal potential, namely a cubic interaction. However, recent results on vibrationally sparse systems have shown that the next higher order anharmonic relaxation term (i.e quartic) is necessary to account for the observed thermally induced dephasing [1-3]. In this work we focus on the importance of anharmonic relaxation mechanisms by creating a large vibrational energy gap. One expects the mode immediately above the gap to have an increased lifetime relative to other vibrational modes of the molecule due to the absence of any cubic decay channels.
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Spears, Kenneth G., i Xiaoning Wen. "Vibrational Dynamics in Electron Transfer". W Modern Spectroscopy of Solids, Liquids, and Gases. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/msslg.1995.stha2.
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Electron transfer is a widely studied and important phenomena with an extensive literature. The measurement of electron transfer (ET) rates as a function of vibrational state has been a long sought goal for testing the vibrational reorganization component of electron transfer. Prior insight into vibrational effects has been indirect, initially through correlations of rate versus exothermicity for a variety of compounds, and more recently through Raman spectroscopic identification of important vibrational modes. A direct electron transfer rate measurement for two vibrational states and subsequent identification of the final vibrational quantum numbers following electron transfer have been measured in our recent work for the first time.1
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Ikeda, Katsuyoshi. "In-situ ultra-low frequency SERS spectroscopy at electrified interfaces". W JSAP-OSA Joint Symposia. Washington, D.C.: Optica Publishing Group, 2018. http://dx.doi.org/10.1364/jsap.2018.19p_211b_8.
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Surface-specific vibrational spectroscopy is recognized as a powerful tool for in-situ observation of electrode/electrolyte interfaces. However, terahertz (THz) or far-infrared (FIR) absorption spectroscopy is hardly applicable to in-situ observation of such “buried” interfaces, especially for detecting low frequency extramolecular vibrations including rich information on electrode/molecule interactions. On the other hand, surface enhanced Raman scattering (SERS) spectroscopy has a potential advantage in detecting such low frequency vibration modes even under electrochemical conditions.
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Murray, Cherry A. "Multichannel Raman spectroscopy of monolayers on surfaces using a CCD Detector". W Quantum-Limited Imaging and Image Processing. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/qlip.1986.tub1.
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Currently available detector technology is beginning to make possible high resolution spontaneous Raman spectroscopy of surfaces, metals, and other systems containing as few as 1011 molecules. Raman scattering is an inelastic process in which an incident photon either gives up or creates an intrinsic quantum of energy in matter. We are interested in the use of Raman scattering as a probe of fingerprint vibrational levels of molecules, for which the change of energy of the incident light is about 0.01 - 0.1 electron volts or 80 - 800 cm−1. The advantages of Raman scattering as a vibrational spectroscopy are its high resolution coupled with a large frequency range. Typically 1 cm−1 resolution is all that is needed for a tenth the linewidth of a vibrational mode of an adsorbate on a metal surface, for example; and a range of 20 to 4000 cm−1 spans a reasonable vibrational range for most adsorbates. Typical surface bonds for small molecules are in the 100 to 500 cm−1 range. Both the resolution and spectral range are quite easy to achieve with visible laser collection optics, detectors and spectrometers. Spontaneous Raman scattering is a process that can be described by second order perterbation theory involving two electric dipole matrix elements and a resonant denominator Raman scattering has different quantum mechanical selection rules for allowed vibrational modes than do infrared absorption (IR) or high resolution electron energy loss (HREELS), and complements these other more traditional surface vibrational spectroscopies. At the same time, Raman scattering has about an order of magnitude better freqency resolution than HREELS and considerably better frequency range than IR, which is currently limited to above about 1000 cm−1 in surface experiments.
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Weiner, A. M., D. E. Leaird, G. P. Wiederrecht i K. A. Nelson. "Femtosecond multiple pulse impulsive simulated Raman scattering in α-perylene molecular crystals". W OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.fx5.
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Generation of coherent optic phonons through impulsive stimulated Raman scattering (ISRS) can occur whenever a sufficiently short optical pulse passes through a Raman active medium. The first experiments demonstrating ISRS were performed with α-perylene molecular crystals1; subsequently, similar observations were reported for a variety of other materials. One difficulty which can be associated with the impulsive scattering technique is an inherent lack of mode selectivity. In this paper we demonstrate multiple pulse impulsive stimulated Raman scattering, a powerful new technique for achieving mode selectivity in ISRS experiments. By using phase-only spectral filtering techniques, we efficiently generate terahertz repetition-rate bursts of femtosecond pulses,2 which we use for repetitive impulsive excitation in our experiments. Individual phonon modes are selected by tuning the pulse repetition rate to the vibrational period. We demonstrate this concept by selectively and individually exciting the 104-cm™1 vibrational mode and the 80-cm™1 librational mode in α-perylene molecular crystals. This technique permits direct observation of the individual cycles of the vibrational and librational oscillations, without the mode beating which occurred in previous experiments,1 and makes possible accurate measurements of the dephasing times.