Physical Properties of Some ET-Based Organic Metals and Superconductors with Mercury Containing Anions

Because of mercury atoms capability of forming the compounds with various coordination, the application of the electrolytes with Hg containing anions in electrochemical oxidation of ET (bis(ethylenedithio)tetrathiafulvalene) results in the formation of ET salts with the anions of different composition. The properties of organic metals and superconductors are briefly described for three families: 1) ET$_4$Hg$_{3-\delta}$X$_8$ (($\delta 0$, and a series of other peculiarities. Shubnikov-de Haas oscillations were observed for some salts of (ET)$_8$[ Hg$_4$X$_{12}$(C$_6$H$_5$Y)$_2$] family. The possible types of Fermi surface are discussed for these salts

Shubnikov-de Haas Oscillations in New Organic Conductors (ET)8\mathsf{_8}[ Hg4\mathsf{_4}Cl12\mathsf{_{12}}(C6\mathsf{_6}H5\mathsf{_5}Cl)2\mathsf{_2}] and (ET)8\mathsf{_8}[ Hg4\mathsf{_4}Cl12\mathsf{_{12}}(C6\mathsf{_6}H5\mathsf{_5}Br)2\mathsf{_2}]

The results of the investigations of Shubnikov-de Haas oscillations in the quasi-two-dimensional organic complexes (ET)${_8}$[ Hg$_4$Cl$_{12}$(C$_6$H$_5$Cl)$_2$] , where X = CI, Br in the magnetic fields up to 40 T were reported. These results allow one to obtain some information about Fermi surface in the mentioned complexes. Shubnikov-de Haas oscillations in the compound with X = Cl correspond at least to two different cylindrical sheets of Fermi surface with the cross-section in (bc)-plane of 13% and 20% Brillouin zone cross-section. Shubnikov-de Haas oscillations in the complex with X = Br correspond to one cylindrical sheet with the cross-section in (bc)-plane of 13% of Brillouin zone cross-section. The experimental results for the complex with X = Br more agree with the theoretical calculations of Fermi surface than for the complex with X = Cl.

On physical properties of the organic metal (BEDT-TTF)4Hg 3 _ δCl8

Conduction electron spin résonance study is presented together with static susceptibility, thermopower and IR absorption measurements for (BEDT-TTF) 4Hg3-δCl8. It is shown that the strong exchange interactions lead to a single ESR line broadened by the spin-orbit coupling ; the role of two-dimensionality of the salt is emphasized. The two-dimensionality of the spin ordering is also stated. The anomalies of the ESR parameters near 80 K may be associated with a phase transition caused probably by the deformation of the incommensurate Hg sublattice. Our study confirms that the anisotropy of the spectral (IR, ESR) properties does not necessarily agree with that of the transport properties of the organic metal.Nous présentons des études de résonance paramagnétique sur les électrons de conduction du (BEDT-TfF)4Hg3-δCl8, complétées par des mesures de susceptibilité paramagnétique statique, de force thermoélectrique et d'absorption IR. Nous avons montré que les interactions d'échange fortes conduisent à un spectre RPE simple, élargi par le couplage spin-orbite. La bidimensionalité du système de spin a été également confirmée. Des anomalies ont été observées près de 80 K pour certaines propriétés physiques ; nous supposons qu'elles sont provoquées par une déformation du réseau des ions Hg. Nous avons démontré que l'anisotropie spectrale (RPE, IR) n'est pas toujours comparable à l'anisotropie de transport électrique du métal organique

Enhanced Raman scattering provided by fullerene nanoclusters

Two new nonlinear optic effects are observed in crystalline solutions of fullerenes in toluene and carbon tetrachloride. Both are provided by a self-clustering of the solute molecules and are referred to fullerene-enhanced Raman scattering and solvent-enhanced luminescence. The effects are induced by the excitation of charge-transfer states of the fullerene nanoclusters, which makes the latter act as amplifiers of local electric fields. © 2008 Pleiades Publishing, Ltd

Enhanced Raman scattering provided by fullerene nanoclusters

Two new nonlinear optic effects are observed in crystalline solutions of fullerenes in toluene and carbon tetrachloride. Both are provided by a self-clustering of the solute molecules and are referred to fullerene-enhanced Raman scattering and solvent-enhanced luminescence. The effects are induced by the excitation of charge-transfer states of the fullerene nanoclusters, which makes the latter act as amplifiers of local electric fields. © 2008 Pleiades Publishing, Ltd

Fullerene-cluster amplifiers and nanophotonics of fullerene solutions

New enhanced linear optical effects were found for crystalline solutions of fullerenes in toluene. They are referred to as enhanced Raman scattering and enhanced luminescence of both solvent and fullerenes and are attributed to clustering the solute molecules themselves and solute and solvent molecules together. The effects are due to the excitation of localized charge-transfer excitons of the fullerene nanoclusters which makes the latter act as amplifiers of local electric fields. © 2009 Society of Photo-Optical Instrumentation Engineers

The nature of enhanced linear and nonlinear optical effects in fullerene solutions

The "blue" emission from fullerene C60 and its derivatives in frozen toluene solution is discovered and analyzed in the framework of the electromagnetic theory of enhanced optical effects. It is shown that the emission, combining enhanced spectra of Raman scattering and one-photon luminescence, is due to clustering of fullerene molecules in solution. Photoexcitation of charge-transfer excitons in clusters provides the polarization required for the enhancement. A direct relationship is established between the observed phenomenon and nonlinear optical properties of the medium. Empirical and computational tests are proposed to select matrices with various nonlinear optical properties. © 2009 Pleiades Publishing, Ltd

Shpolski effect in optical spectra of frozen solutions of the organic C60 fullerene derivative in toluene

The optical spectra of a solution of the C60 ethyl acetate (C60-EA) in toluene are investigated. The absorption spectra measured at T = 80 K reveal a combination of an intense featureless background pedestal deriving from absorption of charge-transfer cluster complexes on which weakly structured molecular absorption is superposed. A decrease in the temperature from 80 to 2 K leads to the appearance of a multiplet of narrow lines (with a width of down to 5 cm-1) corresponding to the optical excitation of C60-EA molecules occupying different inequivalent positions in the matrix. A similar structure is observed in the luminescence spectrum of the C60-EA solution at T = 2 K. The structural luminescence spectrum is in mirror symmetry with the absorption bands. The frequencies of the corresponding transitions and the related molecular vibrations are determined. The allowed character of both mirror-symmetry spectra combined with the exact matching of their constituent frequencies suggests that the vibronic interaction in the molecule is determined by the Frank-Condon mechanism. © 2009 Pleiades Publishing, Ltd

Quantum and semiclassical oscillations in the organic metal, (BEDO-TTF)(2)Cl-x(H2O)(y)

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The nature of enhanced linear and nonlinear optical effects in fullerene solutions

The "blue" emission from fullerene C60 and its derivatives in frozen toluene solution is discovered and analyzed in the framework of the electromagnetic theory of enhanced optical effects. It is shown that the emission, combining enhanced spectra of Raman scattering and one-photon luminescence, is due to clustering of fullerene molecules in solution. Photoexcitation of charge-transfer excitons in clusters provides the polarization required for the enhancement. A direct relationship is established between the observed phenomenon and nonlinear optical properties of the medium. Empirical and computational tests are proposed to select matrices with various nonlinear optical properties. © 2009 Pleiades Publishing, Ltd