Neste trabalho realizou-se um estudo espectroscópico vibracional do dissulfeto de carbono, CS2, puro e em misturas binárias com diferentes solventes moleculares, a fim de investigar as interações soluto/soluto e soluto/solvente. Os solventes utilizados para esse estudo foram diclorometano (CH2Cl2), clorofórmio (CHCl3), clorofórmio deuterado (CDCl3), benzeno (C6H6) e tetracloreto de carbono (CCl4); e as técnicas utilizadas foram as espectroscopias Raman e infravermelho (IV). A análise das bandas Raman do CS2 que formam o dubleto de Fermi (v1-2v2) permite determinar uma série de valores empíricos, chamados de parâmetros de ressonância de Fermi, dentre os quais, o coeficiente de acoplamento de Fermi (W) foi o mais utilizado neste trabalho. Os diferentes valores de W nos diferentes meios são consequência das forças das interações intermoleculares existentes entre CS2/CS2 e CS2/solvente. Os experimentos demonstraram que os valores de W em todas as misturas binárias investigadas aumentam à medida que a fração molar de CS2 diminui. Isto sugere que quando o CS2 é solvatado por diferentes moléculas, há um aumento da anarmonicidade, dependendo do tipo de interação. A análise da banda atribuída ao modo de deformação angular do CS2, v2, realizada a partir dos espectros no infravermelho sugere que em misturas binárias existem dois regimes de solvatação na solução, uma referente às interações CS2/ CS2, onde as moléculas de CS2 estão preferencialmente solvatadas por moléculas de CS2 e outro regime de solvatação referente às interações CS2/solvente, onde CS2 está solvatado por moléculas do solvente em questão. / In this work has performed a vibrational spectroscopic investigation of carbon disulphide, CS2, neat and in binary mixtures with different molecular solvents, aiming at understanding the solute/solute and solute/solvent interactions. The solvents considered for this study were dichloromethane (CH2Cl2), chloroform (CHCl3), deuterated chloroform (CDCl3), benzene (C6H6) and carbon tetrachloride (CCl4); and the techniques used were Raman and infrared (IR) spectroscopies. The analysis of the Raman bands that compose the Fermi doublet (v1-2v2) allows the determination of a series of empirical values, including the coefficient of Fermi coupling (W), used along this work. The different values of W within the different solvents are consequence of the intermolecular forces between CS2/CS2 and CS2/solvent. The experimental data showed that the W values in all investigated binary mixtures increase as the CS2 molar fraction decreases. It suggests that when CS2 is solvated by different molecules, there is an increase of the anarmonicity, depending on the type of the interaction. The analysis of the band assigned to the CS2 bending mode, v2, performed from infrared spectra, suggests that in the binary mixtures there are two solvation regimes in solution, one related to the CS2/CS2 interactions, where the CS2 molecule is preferentially solvated by CS2 molecules, and one where the CS2 is solvated by the respective solvent molecules.

Neste trabalho realizou-se um estudo espectroscópico vibracional do dissulfeto de carbono, CS2, puro e em misturas binárias com diferentes solventes moleculares, a fim de investigar as interações soluto/soluto e soluto/solvente. Os solventes utilizados para esse estudo foram diclorometano (CH2Cl2), clorofórmio (CHCl3), clorofórmio deuterado (CDCl3), benzeno (C6H6) e tetracloreto de carbono (CCl4); e as técnicas utilizadas foram as espectroscopias Raman e infravermelho (IV). A análise das bandas Raman do CS2 que formam o dubleto de Fermi (v1-2v2) permite determinar uma série de valores empíricos, chamados de parâmetros de ressonância de Fermi, dentre os quais, o coeficiente de acoplamento de Fermi (W) foi o mais utilizado neste trabalho. Os diferentes valores de W nos diferentes meios são consequência das forças das interações intermoleculares existentes entre CS2/CS2 e CS2/solvente. Os experimentos demonstraram que os valores de W em todas as misturas binárias investigadas aumentam à medida que a fração molar de CS2 diminui. Isto sugere que quando o CS2 é solvatado por diferentes moléculas, há um aumento da anarmonicidade, dependendo do tipo de interação. A análise da banda atribuída ao modo de deformação angular do CS2, v2, realizada a partir dos espectros no infravermelho sugere que em misturas binárias existem dois regimes de solvatação na solução, uma referente às interações CS2/ CS2, onde as moléculas de CS2 estão preferencialmente solvatadas por moléculas de CS2 e outro regime de solvatação referente às interações CS2/solvente, onde CS2 está solvatado por moléculas do solvente em questão. / In this work has performed a vibrational spectroscopic investigation of carbon disulphide, CS2, neat and in binary mixtures with different molecular solvents, aiming at understanding the solute/solute and solute/solvent interactions. The solvents considered for this study were dichloromethane (CH2Cl2), chloroform (CHCl3), deuterated chloroform (CDCl3), benzene (C6H6) and carbon tetrachloride (CCl4); and the techniques used were Raman and infrared (IR) spectroscopies. The analysis of the Raman bands that compose the Fermi doublet (v1-2v2) allows the determination of a series of empirical values, including the coefficient of Fermi coupling (W), used along this work. The different values of W within the different solvents are consequence of the intermolecular forces between CS2/CS2 and CS2/solvent. The experimental data showed that the W values in all investigated binary mixtures increase as the CS2 molar fraction decreases. It suggests that when CS2 is solvated by different molecules, there is an increase of the anarmonicity, depending on the type of the interaction. The analysis of the band assigned to the CS2 bending mode, v2, performed from infrared spectra, suggests that in the binary mixtures there are two solvation regimes in solution, one related to the CS2/CS2 interactions, where the CS2 molecule is preferentially solvated by CS2 molecules, and one where the CS2 is solvated by the respective solvent molecules.

La circulation de matière et la signature sismique des zones de subduction sont fortement dépendantes despropriétés élastiques de deux grands types de minéraux hydratés : les serpentines (antigorite, lizardite etchrysotile) provenant de l'hydratation des minéraux du manteau et le glaucophane, minéral marqueur des schistesbleus et éclogites, faciès métamorphiques caractéristiques des zones de subduction. La détection de ces phasesest parfois difficile. Il est nécessaire de connaître leurs propriétés élastiques afin de mieux comprendre lesimages sismiques acquises. L'objectif de cette thèse est de mesurer et de calculer les propriétés élastiques deminéraux hydratés par la spectroscopie Brillouin (dans le cas de l'antigorite et du glaucophane) et par les calculsab initio (pour la lizardite). Caractériser au mieux ces propriétés permet de les relier à la sismicité dans les zonesde subduction et notamment aux zones de faibles vitesses détectées par diverses méthodes sismiques. Nosmesures ont été réalisées à l'ambiante pour l'antigorite et le glaucophane et à haute pression pour l'antigorite encellule à enclumes de diamants. Les mesures élastiques ont ensuite été couplées à des mesures d'orientationspréférentielles par Electron Back-Scattered Diffraction. Ceci a permis de quantifier l'anisotropie élevée(AVP=37% et AVS=50%) dans la roche totale ainsi que les vitesses sismiques faibles des ondes P et S. Nousavons pu ainsi relier le décalage des ondes S aux retards observés par sismique dans la zone de subduction deRyukyu (Japon). Les observations sismiques montrent que la serpentine est présente dans les zones où lasismicité est faible et apparaît non seulement comme un minéral essentiel des zones de subduction mais en pluscomme un "lubrifiant" permettant aux couches de glisser les unes sur les autres sans engendrer de séismes. Pourle glaucophane, les schistes bleus présentent une anisotropie plus élevée que les éclogites à glaucophane maisces roches sont toutefois difficiles à détecter avec la profondeur, du fait de leurs vitesses élevées comparables àcelles du manteau environnant. Nos calculs par méthode ab initio portent sur un analogue de l'antigorite, lalizardite pour laquelle nous avons établi les constantes élastiques à diverses pressions et en présence de fer ounon. Nous avons mis en évidence une anomalie élastique vers 5 GPa pour la lizardite et 7 GPa pour l'antigorite,que nous avons confirmée ensuite par des mesures de spectroscopies Brillouin et Raman à haute pression. / The flow of material and the seismic signature of subduction zones are highly dependent on the elastic propertiesof two major types of hydrated minerals: serpentines (antigorite, lizardite and chrysotile) produced by thehydration of mantle minerals and glaucophane, a marker of blueschists and eclogites, which are metamorphicfacies characteristic of subduction zones. Detection of these phases is sometime difficult. It is important to knowtheir elastic properties in order to better understand the seismic images. The goal of this work is to measure andcalculate the elastic properties of hydrated minerals by Brillouin spectroscopy (for antigorite and glaucophane)and ab initio calculations (for lizardite). The precise knowledge of such properties allows linking them to theseismicity in the subduction zones including areas of low velocities detected by various seismic methods. Ourmeasurements were performed at room conditions for antigorite and glaucophane and at high-pressure forantigorite in a diamond anvil cell. Elastic measurements were then coupled with measurements of latticepreferredorientations by Electron Back-Scattered Diffraction. This allowed quantifying the high anisotropy(AVP= 37% and AVS= 50%) in the whole rock and the low seismic velocities of P and S waves. We were able tolink it to the shear wave splitting observed by seismology in the Ryukyu arc (Japan). Seismic observations showthat serpentine is present in areas of low seismicity; it appears to be not only an essential mineral of thesubduction zones but also a “lubricant” allowing sliding layers to slip over each other without leading toearthquakes. For glaucophane, blueschists exhibit a higher anisotropy than glaucophane eclogites, but theserocks are difficult to detect at higher depth, because of their high velocities comparable to those of thesurrounding mantle. We performed ab initio calculations for a similar serpentine, the lizardite, for which weestablished the elastic constants at various pressures and in the presence of iron or not. We highlighted ananomaly around 5 GPa for lizardite and 7 GPa for antigorite, which was later confirmed by Brillouin and Ramanspectroscopies at high pressure.

Raman spectroscopy involves change in the polarizability of the molecular system on excitation and is based on scattering process. Spontaneous Raman scattering is a two photon process, in which the input light initiates the excitation, which then leads to an emission of another photon due to scattering. It is extensively used to understand molecular properties. As spontaneous Raman scattering is a weak process, the detection of these weak Raman photons are rather difficult. Alternatively, resonance Raman (RR) scattering is another technique where the excitation wavelength is chosen according to the material under study. The excitation wavelength is chosen to be within the absorption spectrum of the material under study. RR spectroscopy not only provides considerable improvement in the intensity of the Raman signal, but also provides mode specific information i.e. the modes which are Franck-Condon active in that transition can be observed. There are reports on RR studies of many systems using pulsed light as an excitation source. It is necessary to use at least two pulsed laser sources for carrying out the time resolved RR spectroscopy. A single pulse source for excitation would lead to compromise either with temporal or spectral resolution which is due to the uncertainty principle. If an excitation pulse has pulse width of ~100 femtoseconds then the spectral resolution will be ~ 150 cm-1. It is clear now that for improving the temporal and spectral resolution simultaneously, usage of single pulse for Raman experiments (spontaneous scattering) is not adequate. The usage of multiple laser pulses may provide the way out to improve the resolutions. Nonlinear spectroscopy in a broad view helps in understanding the structural and dynamical properties of the molecular systems in a deeper manner. There are a number of techniques as a part of nonlinear spectroscopy that have emerged in due course to meet different requirements and to overcome some difficulties while understanding the molecular properties. Stimulated Raman (SRS) gain, coherent anti-Stokes Raman scattering (CARS) and the inverse Raman spectroscopy are a few to mention as third order nonlinear spectroscopic techniques which give the similar kind of information about the molecular systems. Stimulated Raman scattering is a more general process involved in nonlinear Raman processes. SRS involves at least two laser pulses and the difference in their frequencies should match with the vibrational frequency of the molecule. The polarization has to be matched between the Raman pump and the Raman probe pulses. We have developed a new nonlinear Raman technique in our laboratory named as ultrafast Raman loss spectroscopy (URLS) using the principles of nonlinear Raman scattering. It involves the Raman pump (~ 1 picosecond (ps) or ~ 15 cm-1spectral resolution) and Raman probe as a white light continuum (100 fs) whose frequency components ranges from 400-900 nm. The laser system consists of Tsunami which is pumped by a Millennia laser and Spitfire-Pro, a regenerative amplifier which is pumped by an Empower laser. Tsunami provides a 100 fs, 780 nm centered, 80 MHz and ~6 nJ energy laser pulses. The Tsunami output is fed into Spitfire to amplify its energy and change the repetition rate to 1 KHz. The pulse length of the input pulse is preserved in amplification. The output of amplifier is split into two equal parts; one part is used to pump the Optical Parametric Amplifier (OPA) in order to generate wavelengths in the range 480-800 nm. The output of the OPA is utilized to generate Raman pump which has to be in ps in order to get the best spectral resolution. A small portion of the other part of amplifier output is utilized to generate white light source for the Raman probe. The remaining part of the amplifier output is used to pump TOPAS to generate wavelengths in the ultraviolet region. URLS has been applied to many molecular systems which range from non-fluorescent to highly fluorescent. URLS has been demonstrated to be very sensitive and useful while dealing with highly fluorescent systems. URLS is a unique technique due to its high sensitivity and the Raman loss signal intensity is at least 1.5-2 times higher as compared to the Raman gain signal intensities. Cresyl violet perchlorate (CVP) is a highly fluorescent system. URLS has been applied to study CVP even at resonance excitation. Rhodamine B has also been studied using URLS. Spontaneous Raman scattering is very difficult to observe experimentally in such high quantum yield fluorescent systems. The variation in the lineshapes of the Raman bands for different RP excitation wavelengths in URLS spectra shows the mode dependent behavior of the absorption spectrum. The experimental observation of variation in the lineshape has been accounted using theoretical formalism. The thesis is focused on discussing the development of the new nonlinear Raman spectroscopic technique URLS in detail and its applicability to molecular systems for better understanding. A theoretical formalism for accounting the uniqueness of URLS among the other nonlinear Raman techniques is developed and discussed in various pictorial representations i.e. ladder, Feynman and closed loop diagrams. A brief overview of nonlinear spectroscopy and nonlinear Raman spectroscopy is presented for demonstrating the difference between the URLS and the other nonlinear Raman techniques.