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Showing papers on "Brillouin zone published in 2000"


Journal ArticleDOI
Alexei Kitaev1
TL;DR: In this article, a condition for boundary Majorana fermions is expressed as a condition on the bulk electron spectrum, which is satisfied in the presence of an arbitrary small energy gap induced by proximity of a 3-dimensional p-wave superconductor, provided that the normal spectrum has an odd number of Fermi points in each half of the Brillouin zone.
Abstract: Certain one-dimensional Fermi systems have an energy gap in the bulk spectrum while boundary states are described by one Majorana operator per boundary point. A finite system of length $L$ possesses two ground states with an energy difference proportional to $\exp(-L/l_0)$ and different fermionic parities. Such systems can be used as qubits since they are intrinsically immune to decoherence. The property of a system to have boundary Majorana fermions is expressed as a condition on the bulk electron spectrum. The condition is satisfied in the presence of an arbitrary small energy gap induced by proximity of a 3-dimensional p-wave superconductor, provided that the normal spectrum has an odd number of Fermi points in each half of the Brillouin zone (each spin component counts separately).

2,986 citations


Journal ArticleDOI
TL;DR: In this paper, the authors studied the linewidth narrowing observed in Brillouin fiber ring laser in the framework of the usual three-wave model of stimulated BrillouIN scattering and showed that the phase noise of the pump laser is transferred to the emitted Stokes wave after being strongly reduced and smoothed under the combined influence of the acoustic damping and the cavity feedback.
Abstract: The linewidth narrowing observed in Brillouin fiber ring lasers is studied within the framework of the usual three-wave model of stimulated Brillouin scattering. We show that the phase noise of the pump laser is transferred to the emitted Stokes wave after being strongly reduced and smoothed under the combined influence of the acoustic damping and the cavity feedback. We then derive a simple analytical relation connecting the full width at half maximum of the Stokes linewidth to that of the pump laser.

204 citations


Journal ArticleDOI
14 Jul 2000-Science
TL;DR: In this paper, the doping and temperature dependence of photoemission spectra near the Brillouin zone boundary of Bi2Sr2CaCu2O8+δ are investigated.
Abstract: We report that the doping and temperature dependence of photoemission spectra near the Brillouin zone boundary of Bi2Sr2CaCu2O8+δexhibit unexpected sensitivity to the superfluid density. In the superconducting state, the photoemission peak intensity as a function of doping scales with the superfluid density and the condensation energy. As a function of temperature, the peak intensity shows an abrupt behavior near the superconducting phase transition temperature where phase coherence sets in, rather than near the temperature where the gap opens. This anomalous manifestation of collective effects in single-particle spectroscopy raises important questions concerning the mechanism of high-temperature superconductivity.

201 citations


Journal ArticleDOI
TL;DR: In this article, the dielectric function of a range of nonmetallic crystals of various lattice types was studied by means of a real-space and full-potential time-dependent density-functional method within the adiabatic local density approximation.
Abstract: The dielectric function of a range of nonmetallic crystals of various lattice types is studied by means of a real-space and full-potential time-dependent density-functional method within the adiabatic local-density approximation. Results for the dielectric constant e ‘ ~at optical frequencies! are given for crystals in the sodium chloride, the fluoride, the wurtzite, the diamond, and the zinc-blende lattice structure. The frequency-dependent dielectric function e(v) for the crystals in the diamond and zinc-blende lattice structure are also presented. We compare our calculated results with experimental data and other theoretical investigations. Our results for the dielectric constants e ‘ and the dielectric functions e(v) are in good agreement with the experimental values. The accuracy of the results is comparable to the one which is commonly found for time-dependent densityfunctional theory calculations on molecular systems. On average we find a deviation of 4‐5 % from experiment for the group IV and III-V compounds in the wurtzite, zinc-blende and diamond lattice structure, 8‐9 % for the II-VI and I-VII compounds in the zinc-blende and sodium chloride lattice structure, and up to 14% deviation for the fluoride lattice structure. The spectral features of the dielectric functions e(v) appear in the

141 citations


Journal ArticleDOI
TL;DR: In this paper, a model of electrons interacting with a magnetic resonance and using it to analyze angle resolved photoemission and tunneling data in the superconducting state of Bi{sub 2]Sr {sub 2}CaCu{sub 8+{delta}}.
Abstract: Motivated by neutron scattering data, we develop a model of electrons interacting with a magnetic resonance and use it to analyze angle resolved photoemission and tunneling data in the superconducting state of Bi{sub 2}Sr {sub 2}CaCu{sub 2}O{sub 8+{delta}} . We not only can explain the peak-dip-hump structure observed near the ({pi},0) point, and its particle-hole asymmetry as seen in superconductor-insulator-normal tunneling spectra, but also its evolution throughout the Brillouin zone, including a velocity ''kink'' near the d -wave node.

131 citations


Journal ArticleDOI
TL;DR: A low-loss, long-range, single-ended distributed optical fiber sensor to measure both temperature and strain simultaneously and unambiguously and both strain and temperature measurements can be independently resolved is demonstrated.
Abstract: We demonstrate a low-loss, long-range, single-ended distributed optical fiber sensor to measure both temperature and strain simultaneously and unambiguously By using the Landau-Placzek ratio and cascaded Mach-Zehnder interferometric filters, we measure both the intensity and the frequency changes in the Brillouin backscattered signal Strain and temperature measurements can then be independently resolved A temperature resolution of 4°C, a strain resolution of 290 µepsilon, and a spatial resolution of 10m have been achieved for a sensing length of 15 km

129 citations


Patent
18 Dec 2000
TL;DR: In this paper, the relative frequency separation between the lasers is adjusted to align the frequency of the backscattered Brillouin signal with a desired sideband in the carrier signal to effect a Brillousin gain on the sideband.
Abstract: Opto-electronic devices and techniques using Brillouin scattering to select a sideband in a modulated optical carrier signal for amplification. Two lasers respectively provide a carrier signal beam and a Brillouin pump beam which are fed into an Brillouin optical medium in opposite directions. The relative frequency separation between the lasers is adjusted to align the frequency of the backscattered Brillouin signal with a desired sideband in the carrier signal to effect a Brillouin gain on the sideband. This effect can be used to implement photonic RF signal mixing and conversion with gain, conversion from phase modulation to amplitude modulation, photonic RF frequency multiplication, optical and RF pulse generation and manipulation, and frequency-locking of lasers.

119 citations


Journal ArticleDOI
TL;DR: Bound states made from two triplet excitations on the Shastry-Sutherland lattice based on the perturbative unitary transformation by flow equations quantitative properties like dispersions and qualitative properties like symmetries are determined.
Abstract: Bound states made from two triplet excitations on the Shastry-Sutherland lattice are investigated. Based on the perturbative unitary transformation by flow equations quantitative properties like dispersions and qualitative properties like symmetries are determined. The high order results [up to (J2/J1)(14)] permit one to fix the parameters of SrCu2(BO3)(2) precisely: J1 = 6.16(10) meV, x J2/J1 = 0.603(3), J( perpendicular) = 1.3(2) meV. At the border of the magnetic Brillouin zone a general double degeneracy is derived. An unexpected instability in the triplet channel at x = 0.63 indicates a transition towards another phase. The possible nature of this phase is discussed.

111 citations


Journal ArticleDOI
TL;DR: This study reveals the processes responsible for a broadening of the Brillouin loss curve when the probe pulse duration is reduced, followed by a sudden and rather surprising reduction of the linewidth when the pulse duration gets shorter than the acoustic relaxation time.
Abstract: We perform numerical simulations on a model describing a Brillouin-based temperature and strain sensor, testing its response when it is probed with relatively short pulses. Experimental results were recently published [e.g., Opt. Lett. 24, 510 (1999)] that showed a broadening of the Brillouin loss curve when the probe pulse duration is reduced, followed by a sudden and rather surprising reduction of the linewidth when the pulse duration gets shorter than the acoustic relaxation time. Our study reveals the processes responsible for this behavior. We give a clear physical insight into the problem, allowing us to define the best experimental conditions required for one to take the advantage of this effect.

101 citations


Journal ArticleDOI
TL;DR: In this article, the electronic energy band structure, site and angularmomentumdecomposed densities of states (DOS) and charge-density contours of perovskite SrTiO3 in the paraelectric cubic phase are calculated by the first-principles tight-binding linear muffin-tin orbitals method with atomic sphere approximation using density functional theory in its local density approximation.
Abstract: The electronic energy band structure, site- and angular-momentum-decomposed densities of states (DOS) and charge-density contours of perovskite SrTiO3 in the paraelectric cubic phase are calculated by the first-principles tight-binding linear muffin-tin orbitals method with atomic sphere approximation using density functional theory in its local density approximation. The calculated band structure shows a direct band gap of ~1.4 eV at the gamma point in the Brillouin zone. The total DOS is compared with experimental x-ray photoemission spectra. From the DOS analysis, as well as charge-density studies, we conclude that the bonding between Sr and TiO3 is mainly ionic and that the TiO3 entities bond covalently. Using the projected DOS and band structure we have analysed the interband contribution to the optical properties of SrTiO3 . The real and imaginary parts of the dielectric function and hence the optical constants (such as the reflectivity, refractive index, extinction coefficient and absorption coefficient) and the electron energy-loss spectrum are calculated. The calculated spectra are compared with the experimental results for SrTiO3 in the cubic phase and are found to be in good agreement with the experimental results in low-energy regions. The role of band-structure calculation as regards the optical properties of SrTiO3 is discussed.

77 citations


Journal ArticleDOI
TL;DR: The structural properties and the band structures of the charge transfer insulating oxides SrO, MgO and SrTiO3 are computed both within density functional theory in the local density approximation (LDA) and in Hedin's GW-scheme for self-energy corrections, by using a model dielectric function, which approximately includes local field and dynamical effects as mentioned in this paper.
Abstract: The structural properties and the band structures of the charge-transfer insulating oxides SrO, MgO and SrTiO3 are computed both within density functional theory in the local density approximation (LDA) and in Hedin's GW -scheme for self-energy corrections, by using a model dielectric function, which approximately includes local field and dynamical effects. The deep valence states are shifted by the GW -method to higher binding energies, in very good agreement with photoemission spectra. Since in all of these oxides the direct gaps at high-symmetry points of the Brillouin zone may be very sensitive to the actual value of the lattice parameter a already at the LDA level, self-energy corrections are computed both at the theoretical and the experimental a . For MgO and SrO, the values of the energies of transition between the valence and the conduction bands are improved by GW -corrections, while for SrTiO3 they are overestimated. The results are discussed in relation to the importance of local field effects and to the nature of the electronic states in these insulating oxides.

Journal ArticleDOI
TL;DR: In this article, a new advanced space and time-resolved Brillouin light scattering (BLS) technique is used to study diffraction of two-dimensional beams and pulses of dipolar spin waves excited by strip-line antennas in tangentially magnetized garnet films.
Abstract: A new advanced space- and time-resolved Brillouin light scattering (BLS) technique is used to study diffraction of two-dimensional beams and pulses of dipolar spin waves excited by strip-line antennas in tangentially magnetized garnet films. The new technique is an effective tool for investigations of two-dimensional spin wave propagation with high spatial and temporal resolution. Linear effects, such as the unidirectional exci-tation of magnetostatic surface waves and the propagation of backward volume magnetostatic waves (BVMSW) in two preferential directions due to the non-collinearity of their phase and group velocities are investigated in detail. In the nonlinear regime stationary and non-stationary self-focusing effects are studied. It is shown, that non-linear diffraction of a stationary BVMSW beam, having a finite transverse aperture, leads to self-focusing of the beam at one spatial point. Diffraction of a finite-duration (non-stationary) BVMSW pulse leads to space-time self-focusing and formation of a strongly localized two-dimensional wave packet (spin wave bullet). Numerical modeling of the diffraction process by using a variational approach and direct numerical integration of the two-dimensional non-linear Schrodinger equation provides a good qualitative description of the observed phenomena.

Journal ArticleDOI
TL;DR: Transverse collective modes of strongly coupled dusty plasmas are studied in the fluid phase and it is shown that shear modes do not exist at long wavelengths but do exist above a critical wave vector.
Abstract: Transverse collective modes of strongly coupled dusty plasmas are studied in the fluid phase. A memory function approach based on the generalized viscosity is employed to capture both the hydrodynamic limit and the second-moment sum rule. It is shown that shear modes do not exist at long wavelengths but do exist above a critical wave vector. Above the critical wave vector strong coupling gives rise to an incipient Brillouin structure in the dispersion. The emergence and damping of the shear mode is shown to depend on the generalized viscosity and a generalized relaxation time. Agreement with simulation data is shown to be excellent.

Journal ArticleDOI
TL;DR: The use of Brillouin-Wigner perturbation theory in describing many-body systems is critically re-examined in this paper, where the authors consider the use of perturbations in the context of many body systems.
Abstract: The use of Brillouin-Wigner perturbation theory in describing many-body systems is critically re-examined.

Journal ArticleDOI
TL;DR: The band structure of absorptive dielectric photonic crystals is investigated in this article, where the frequency-dependent electric permeability e(x,ω) satisfies certain analyticity requirements as a function of frequency and it is shown that no bandgaps exist in frequency regions where absorption takes place.
Abstract: The band structure of absorptive dielectric photonic crystals is investigated. Provided the frequency-dependent electric permeability e(x,ω) satisfies certain analyticity requirements as a function of frequency, we show that no bandgaps exist in frequency regions where absorption takes place, i.e. where e(x,ω) has a non-zero imaginary part. In this case real eigenvalues of the Helmholtz operator in the Bloch-decomposed formalism are absent. Using a suitable analytic continuation procedure, we find that the former change into resonances, i.e. complex numbers depending on k, the wavevector from the first Brillouin zone, thus leading to complex bands in the lower half plane. This is confirmed numerically for a simple, one-dimensional example.

Journal ArticleDOI
TL;DR: The study of dye-doped low pitch cholesteric liquid crystals in their blue phases as an example of tunable "weak" photonic crystals is proposed and demonstrated and fluorescence emission of the dyes is shown to be affected by the presence of the blue phases.
Abstract: The study of dye-doped low pitch cholesteric liquid crystals in their blue phases as an example of tunable ‘‘weak’’ photonic crystals is proposed and demonstrated. The presence of the blue phases in cholesterics can be tuned with temperature, and this allows for an easy in situ comparison of the emission and/or absorption of the dyes with or without an enwrapping lattice of disclination lines. The fluorescence emission of the dyes is shown to be affected by the presence of the blue phases. Although unlikely to be suitable for real applications ~due to the natural low refractive index contrast!, these systems may represent unique examples of tunable photonic crystals. It is proposed that single crystals of dye-doped blue phases should provide a very interesting testing ground for the study of optical emission anisotropies which can, on the other hand, be controlled by an external parameter. PACS number~s!: 42.70.Qs, 42.70.Df, 61.30.Jf The idea of controlling the spontaneous emission of atoms and molecules by means of a modification in the photon density of states ~DOS! was put forward more than ten years ago in the pioneering work of Yablonovich @1#, and the denomination photonic crystals was coined to identify those structures that alter the otherwise isotropic distribution of electromagnetic modes in vacuum. The vast majority of examples achieve a modification in the photonic DOS by virtue of a spatially dependent dielectric function e(r), which plays a role similar to that of the position dependent atomic potential V(r W) in the electronic structure of matter ~except for the fact that electromagnetic waves are a vectorial field, while electrons are scalar waves! .I fe(r) is periodic, the full power of the Bloch theorem can be applied, and the electromagnetic band structure can be obtained. This sometimes results in the presence of gaps which are opened at the Brillouin zone boundaries. In analogy with other elementary excitations in solids, a rule of thumb is that the electromagnetic wavelength l should be of the order of the lattice spacing a in order to see a standing wave interference ~Bragg reflection! and the presence of forbidden energies. For this reason, most of the original work was performed in the microwave region, whereas l is of the order of macroscopic objects and, therefore, three-dimensional periodic lattices could be built

Journal ArticleDOI
TL;DR: In this paper, the electronic structure of Ti3SiC2 was investigated by means of first-principles self-consistent total energy calculations within the local-density approximation using the full-potential linea...
Abstract: We have investigated the electronic structure of Ti3SiC2 by means of first-principles self-consistent total-energy calculations within the local-density approximation using the full-potential linea ...

Journal ArticleDOI
TL;DR: The dynamical structure factor of vitreous silica has been measured by inelastic x-ray scattering varying the exchanged wave vector at fixed exchanged energy, obtaining the first direct evidence of Brillouin peaks in the S(Q,E) of SiO2 at energies above the boson peak energy.
Abstract: The dynamical structure factor [ S(Q,E)] of vitreous silica has been measured by inelastic x-ray scattering varying the exchanged wave vector ( Q) at fixed exchanged energy ( E)-an experimental procedure that, contrary to the usual one at constant Q, provides spectra with much better identified inelastic features. This allows us to obtain the first direct evidence of Brillouin peaks in the S(Q,E) of SiO2 at energies above the boson peak (BP) energy, a finding that excludes the possibility that the BP marks the transition from propagating to localized dynamics in glasses.

Journal ArticleDOI
TL;DR: In this article, the authors study the dynamics of ultracold atoms in an optical lattice under constant bias and show that the Bloch-Zener model is remarkably stable against the condensate's nonlinear self-interaction.
Abstract: We study the dynamics of ultracold atoms in an optical lattice under constant bias. After recapitulating the ideas underlying Bloch oscillations and Zener's formula for interband transitions, the Bloch-Zener scenario is tested by means of accurate numerical solutions to the time-dependent Schr?dinger equation. It is shown how two shortcomings of the traditional Zener formula can be removed: the common weak-binding approximation can be circumvented by combining Kohn's insight into the structure of complex energy bands with the Dykhne-Davis-Pechukas description of transitions in terms of adiabatic excursions on analytically continued eigenvalue surfaces, and a usually neglected Stokes phenomenon comes into play when accounting for the finite width of the Brillouin zone. Treating Bose-Einstein condensates in optical lattices within the standard mean-field approximation at zero temperature, the ideal Bloch-Zener scenario turns out to be remarkably stable against the condensate's nonlinear self-interaction. Yet, under appropriate conditions a Bloch-oscillating Gross-Pitaevskii wavepacket reveals characteristic signatures of that nonlinearity, such as sudden phase jumps, slight shifts of the oscillation frequency or non-classical breathing modes. It is suggested that such experimentally detectable signatures will play an important role in future high-precision experiments aiming at the exploration of many-body dynamics in periodic potentials with condensates in optical lattices.

Journal ArticleDOI
Klaus Stöwe1
TL;DR: In this paper, it was shown that the polyanionic square nets are distorted in LaTe 2 into herringbone patterns of dimer pairs with interatomic distances of 298.7 and 303.6 pm within the dimers.

Journal ArticleDOI
TL;DR: In this article, a spin-fluctuation mechanism was proposed for the pairing state with the gap maxima along the Brillouin zone in neutron-scattering data, which is consistent with the reported thermodynamic and transport data.
Abstract: We have analyzed heat capacity and thermal conductivity measurements of ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$ in the normal and superconducting state and come to the conclusion that an order parameter with nodal lines on the Fermi surface is required to account for the observed low-temperature behavior. A gapped order parameter is inconsistent with the reported thermodynamic and transport data. Guided by a strongly peaked dynamical susceptibility along the diagonals of the Brillouin zone in neutron-scattering data, we suggest a spin-fluctuation mechanism that would favor the pairing state with the gap maxima along the zone diagonals (such as for a ${d}_{\mathrm{xy}}$ gap). The most plausible candidates are an odd parity, spin-triplet, f-wave pairing state, or an even parity, spin-singlet, d-wave state. Based on our analysis of possible pairing functions we propose measurements of the ultrasound attenuation and thermal conductivity in the magnetic field to further constrain the list of possible pairing states.

Journal ArticleDOI
TL;DR: The technique of Brillouin light scattering is used to observe strong excitation of magnons in antiferromagnetically coupled trilayers of Fe/Cr/Fe at room temperature, confirming recent theoretical predictions.
Abstract: The technique of Brillouin light scattering is used to observe strong excitation of magnons in antiferromagnetically coupled trilayers of Fe/Cr/Fe at room temperature. The magnons are driven out of equilibrium by a microwave current applied in the trilayer through point contacts. The magnitude of the scattering intensity is investigated as a function of the magnon wave number and applied magnetic field. Confirming recent theoretical predictions, the observations provide strong evidence of electronic spin injection in the rf driving field.

Journal ArticleDOI
TL;DR: The structural properties and the band structures of the charge transfer insulating oxides SrO, MgO and SrTiO3 are computed both within density functional theory in the local density approximation (LDA) and in the Hedin's GW scheme for self-energy corrections, by using a model dielectric function, which approximately includes local field and dynamical effects as mentioned in this paper.
Abstract: The structural properties and the band structures of the charge-transfer insulating oxides SrO, MgO and SrTiO3 are computed both within density functional theory in the local density approximation (LDA) and in the Hedin's GW scheme for self-energy corrections, by using a model dielectric function, which approximately includes local field and dynamical effects. The deep valence states are shifted by the GW method to higher binding energies, in very good agreement with photoemission spectra. Since in all of these oxides the direct gaps at high-symmetry points of the Brillouin zone may be very sensitive to the actual value of the lattice parameter a, already at the LDA level, self-energy corrections are computed both at the theoretical and the experimental a. For MgO and SrO, the values of the transition energies between the valence and the conduction bands are improved by GW corrections, while for SrTiO3 they are overestimated. The results are discussed in relation to the importance of local field effects and to the nature of the electronic states in these insulating oxides.

Journal ArticleDOI
TL;DR: In this article, a Brillouin signal processing based on modification of the optical carrier's magnitude and phase by stimulated Brillour scattering-induced depletion is proposed, which offers wideband processing and low noise and requires only low optical power.
Abstract: We introduce a novel concept in Brillouin signal processing based on modification of the optical carrier’s magnitude and phase by stimulated Brillouin scattering–induced depletion. The technique offers wideband processing and low noise and requires only low optical power. Application to the enhancement of a 25-km high-frequency analog link is experimentally demonstrated and yields a 6.5-GHz bandwidth extension and a 13-dB reduction in the link insertion loss without intermodulation distortion.

Journal ArticleDOI
TL;DR: In this paper, a detailed high-resolution angle-resolved photo-emission study of the electronic band structure of the room-temperature quasicommensurate charge-density-wave phase of the Ta $5d$ derived band was presented.
Abstract: We present a detailed high-resolution angle-resolved photoemission study of the electronic band structure of the room-temperature quasicommensurate charge-density-wave phase of $1T\ensuremath{-}{\mathrm{TaS}}_{2}.$ In particular, we show that no crossings of the Fermi level are visible in the complete Brillouin zone, indicating that an electron-electron correlation-induced pseudogap in the Ta $5d$ derived band exists already above the Mott localization-induced transition at 180 K. Moreover, we find that the electronic structure is governed by at least two quasiparticle peaks, which can be assigned to electrons from starlike shells of Ta atoms within the distorted crystal lattice. These peaks show quasilocalized (dispersionless) behavior in parts of the Brillouin zone where the one-particle band is unoccupied and they follow the one-particle dispersion in the occupied part. In order to address the question of possible Fermi-surface (FS) nesting, we scanned the remaining remnant FS and found regions with a considerable decrease of spectral weight. However, we find no clear evidence for FS nesting.

Journal ArticleDOI
TL;DR: In this paper, the stability of the perovskite-like structures of MgSiO3 at T fixme=0 have been studied using the local density approximation, calculating the Hellmann-Feynman forces, applying the direct method and deriving the phonon dispersion relations.
Abstract: Using the local-density approximation, calculating the Hellmann-Feynman forces, applying the direct method and deriving the phonon dispersion relations, the stability of the perovskite-like structures of MgSiO3 at T =0 have been studied. The cubic Pm $$Pm\overline 3 m$$ m phase shows a dispersion-less soft phonon branch spreading from the R to M points of the cubic Brillouin zone. This soft branch persists up to high pressures of 150 GPa. The low-symmetry phases I4/mcm and Imma, P4/mbm can be considered as a result of the soft mode condensation at the M and R points, respectively. These phases prove to be unstable at T =0. The experimentally observed Pmnb phase is a consequence of the intersection of Imma and P4/mbm space groups. Thus, it can be regarded as a simultaneous condensation of two soft modes: one at the M and a second at the R high-symmetry points of the cubic Brillouin zone. The phonon dispersion relations of Pmnb show that this phase is stable and its optical phonons appear above 4.0 THz only.

Journal ArticleDOI
TL;DR: It is proposed that an "opticlike" mode is observed in giant starlike micelles at low volume fractions due mainly to the internal vibration of each hairy particle.
Abstract: Vibrational modes in suspensions of soft colloids in a fluid can be detected experimentally by Brillouin light scattering. Besides the usual acoustic mode, being essentially the longitudinal phonon of the liquid matrix, an ``opticlike'' mode is observed in giant starlike micelles at low volume fractions. We propose that this opticlike mode is due mainly to the internal vibration of each hairy particle.


Journal ArticleDOI
TL;DR: In this paper, an experimental study of the glass transition of meta-toluidine combining several light scattering techniques was performed, and the structural relaxation time was measured in depolarized geometry from the transition temperature up to well above the melting point and found to vary over 13 time decades.
Abstract: An experimental study of the glass transition of meta-toluidine combining several light scattering techniques was performed. The structural relaxation time is measured in depolarized geometry from the glass transition temperature up to well above the melting point and found to vary over 13 time decades. An analysis by means of the idealized Mode Coupling Theory shows that, as found in other aromatic liquids, experimental results obtained in depolarized light scattering can be described by this theory above Tc in a two-decade frequency range. The polarized Brillouin doublet, measured in the backscattering geometry between 176 K and 300 K, is also analyzed. None of the sets of parameters we obtained in fitting those spectra could fulfil all the requirements of this Mode Coupling Theory.

Journal ArticleDOI
TL;DR: In this article, the experimental band structure of Mo(112) and the effects by temperature and adsorbate were presented, and it was found that the reconstruction and/or adsorbation affects the density of states and bands near the Fermi level of a1 symmetry.
Abstract: The experimental band structure of Mo(112) and the effects by temperature and adsorbate are presented. A surface resonance, identified as crossing the Fermi level at about 1/3 from to of surface Brillouin zone, was observed to be very sensitive to both contamination and temperature. We find evidence of adsorbate and temperature induced reconstruction of the Mo(112) surface. Examination of low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) data provides evidence for an adsorbate induced reconstruction of the Mo(112) surface with periodicities consistent with the Fermi level crossing of the surface resonance. The reconstruction is found to occur at coverages as low as 0.03 Langmuirs of oxygen or carbon. The reconstruction and/or adsorbate affects the density of states and bands near the Fermi level of a1 symmetry.