... in second order Raman scattering with 150 nsec pulses ... HEATING, MELTING, DYE LASERS, PHONONS, ABSORPTION, NEODYMIUM LASERS. ...

... IN TWO-PHONON RAMAN SCATTERING IN CUBIC CRYSTALS,. ... RAMAN SPECTROSCOPY, CRYSTAL LATTICES), (*POLARIZATION, RAMAN ...

Research is reported on Raman scattering and infrared absorption in insulators, second sound in solids, and low temperature thermal conductivity of magnetic materials. (Author)

A theory is developed which describes multiphonon resonance Raman scattering (MPSR) processes in polar semiconductors when the primary radiation frequency w/sub l/ is above the fundamental absorption region. A general formula for the MPRS cross-section ba...

The authors investigate the reflection and Raman scattering spectra of the alpha-lithium iodate monocrystal and also determine the real and imaginary parts of the dielectric constant, the refractive index, the absorption coefficient, the nonlinear optical behavior, the oscillator strengths, and the damping constants based on the Kramers-Kroenig relations. ...

Combination of femtosecond Kerr, two photon absorption, and impulsive stimulated Raman scattering (ISRS) experiments have been carried out to investigate the effect of pulse energy and crystal temperature on the generation of coherent polaritons and phonons in <110> cut ZnTe single crystals of three different resistivities. We ...

A facile, rapid, and nondestructive technique for determining the thermal conductivity of individual nanowires based on Raman temperature mapping has been demonstrated. Using calculated absorption efficiencies, the thermal conductivities of single cantilevered Si nanowires grown by the vapor-liquid-solid method are measured and the results agree well with ...

A series of boron-doped polycrystalline diamond films grown by direct current and microwave plasma deposition was studied with Raman and infrared (IR) absorption spectroscopy. A Fano line shape is observed in the Raman spectra for films with a boron concentration in a narrow range near 10[sup 21] cm[sup [minus]3]. The appearance of the ...

The influence of ligand exchange for pyridine onto the structure and phonon spectra of oleic acid-stabilized CdSe nanocrystals (NCs) is studied by resonant Raman and optical absorption spectroscopy, nuclear magnetic resonance and transmission electron microscopy. The removal of oleic acid ligand by pyridine treatment results in change ...

The metastable cubic phase of CdS has been found to be stabilized in the form of nanoparticles. Zinc-blende to Wurtzite structural transformation of CdS nanoparticles, synthesized using chemical precipitation, was investigated using X-ray diffraction (XRD), Raman, photoluminescence (PL) and infrared (IR) absorption spectroscopy. The nanocrystalline powder ...

... Compilation Part Notice ADP013188 TITLE: Raman Studies of Acoustical Phonons in Strained Hexagonal GaN/AlGaN Superlattices ...

... Accession Number : ADP013188. Title : Raman Studies of Acoustical Phonons in Strained Hexagonal GaN/AlGaN Superlattices. ...

... Accession Number : ADA143882. Title : Raman Scattering from Phonons and Magnons in Antiferromagnetic Fe3BO6,. Corporate ...

Two-phonon Raman scattering in cubic crystals, noting use of polarization effect to determine active

A group-theory analysis of phonon symmetries in C60:I4 crystals is performed. The Raman spectra of various fullerites and shungites are investigated.

Calculations of the dispersion of phonons and polaritions in a superlattice show that the frequencies of the phonon and polarition modes may be prescribed by proper design. These modes may be useful as Raman source and Reststrahlen filters. (Author)

The solid-state absorption spectra of Cf(III) ions as a dopant in lanthanide trihalide hosts (LnCl/sub 3/: Ln = Ce, Sm, and Y; LnBr/sub 3/: Ln = Ce, Sm, Tb, and Y; LnI/sub 3/: Ln = Ce and Y) have been recorded. The spectra of Cf(III) have been correlated with the various crystal structures. The phonon Raman spectra and solid-state ...

Coupled electron-phonon systems are studied in order to understand the competition between various structural instabilities and electronic correlation effects. Results are used to explain the absence of the Peierls distortion and the anisotropic metallic behavior in highly doped quasi-one-dimensional systems, such as polyacetylene. Further, a similar approach has been applied ...

... Accession Number : AD0683698. Title : STIMULATED RAMAN EMISSION AND ABSORPTION SPECTROSCOPY. INTENSITY ...

... Raman spectra, *Photoluminescence, *Dye lasers, *Spectroscopy, Laser amplifiers, Interactions, Fluorescence, Laser cavities, Rings, Phonons ...

High purity, aluminum nitride films were grown on (111) oriented silicon substrates by gas source MBE methods. Films thicknesses ranged from 0.1 to 1.0 microns. The optical properties in the infrared regime were studied using Fourier-transform infrared (FTIR) spectroscopy. The vibrational spectrum was also studied using Raman scattering. FTIR absorption ...

Zn(1-x)Co(x)O samples were prepared by a standard solid-state reaction method. Zn(1-x)Co(x)O crystals in the wurtzite structure were obtained with a Co composition of up to 22.1%. The a-�and c-axis lengths increased and decreased, respectively, with an increase in Co composition. Raman spectra showed systematic broadening of the E(2)�(high) phonon mode ...

... PROPERTIES, ISOMERS, PHONONS, RAMAN SPECTRA, RUBIDIUM, ZINC, CHLORINE, POTASSIUM, BARIUM, MANGANESE, FLUORINE. ...

In this paper we will describe in detail the use of Raman scattering with subpicosecond laser pulses for investigating both the Frohlich interactions between electrons and LO phonons and the intervalley electron-phonon interactions. 19 refs., 6 figs.

The electron-phonon coupling was investigated for mid-infrared transitions in silver halide crystals doped with Pr, Dy, or Nd. The temperature dependence of the absorption spectral line widths and the line shifts were measured in mid-infrared absorption lines in these crystals. It was shown that in each case the temperature dependence ...

... Accession Number : AD0482459. Title : PARAMAGNETIC RESONANCE ABSORPTION OF PHONONS IN PINK RUBY. ...

... Title : ABSORPTION OF ELECTROMAGNETIC WAVES IN SEMICONDUCTORS DUE TO ELECTRON COLLISIONS WITH PHONONS IN A ...

GaN samples implanted with O, Ar, Te, Xe and Au ions, at fluences high enough to cause the formation of an amorphous surface or buried layer, are studied using Raman, X-ray absorption near-edge structure (XANES) and Rutherford backscattering (RBS) spectroscopies. The amorphous character of the as-implanted layers is verified by RBS and confirmed also by ...

We have measured the Raman spectra and UV-Vis absorption spectra of linear polyene biomolecules (?-carotene and lycopene) in CS2 at low concentrations (10?6-10?10 mol/L). With decreasing concentration, all the carbon-carbon vibrations form a coherent mode in ordered ?-carotene and lycopene due to extended ?-conjugation that gives strong ...

We report Raman scattering and visible to near-infrared absorption spectra of solid hydrogen under static pressure up to 285 GPa between 20 and 140 K. We obtain pressure dependences of vibron and phonon modes consistent with results previously determined to lower pressures. The results indicate the stability of the ordered ...

The polarization and intensity of Raman scattered light from plasmons and phonons in gallium arsenide was measured and compared to theory. The agreement was good and yielded values of the Raman tensor and the electro-optic coefficient of gallium arsenide....

We present a theoretical investigation of the lattice dynamics of ?-aluminium phosphate (berlinite) which takes only into account short-range interactions and axially symmetric tensor forces between (i) the first nearest-neighbours metal-oxygen or oxygen-oxygen pairs and (ii) the second nearest-neighbours metal-metal pairs. Our calculation accounts satisfactorily for the experimental ...

We provide a topological understanding on phonon Hall effect in dielectrics with Raman spin-phonon coupling. A general expression for phonon Hall conductivity is obtained in terms of the Berry curvature of band structures. We find a nonmonotonic behavior of phonon Hall conductivity as a ...

Amorphous silicon based integrated photonics technology has been a developing field over the last few years. Research to develop several types of photonic devices is ongoing. One of the important materials in this field of research is hydrogenated amorphous silicon (a-Si:H). This material, owing to its easy preparation (hot-wire chemical vapor deposition), large amount of hydrogen intake (for ...

... Therefore the phonon emission prevails over the absorption. The generation rate of the phonons at a given frequency W propagating along a given ...

Oriented polycrystalline films of AlN on Si(111) substrates and amorphous AlN films on sapphire substrates have been prepared by sputter deposition of aluminum in a nitrogen plasma. Phonons at 303, 426, 514, 614, 663, and 831 cm/sup -1/ ( +- 3%) have been observed in the Raman spectra of the crystalline films. The 303-cm/sup -1/ phonon ...

This article report, for the first time, the influence of laser parameters on the spectral response of weblike silicon fibrous nanostructures. These nanostructures are formed by femtosecond laser irradiation at megahertz pulse frequency under atmosphere and nitrogen ambient. The observed decreasing in reflectance is correlated with the density of fibrous nanostructures and the size of the ...

... 1(b), the I LO resonance has a rather complicated structure. ... by phonon sidebands of the resonant PL or by resonant Raman scattering. ...

... Accession Number : ADA436149. Title : Excitation of Coherent Phonons and Plasmons in InSb by Impulsive Raman Scattering. ...

... Accession Number : AD0743987. Title : Zero-Phonon Line Absorption Spectra of Radiation Damage Centers in Silicon. ...

... Accession Number : ADD851778. Title : TWO-PHONON ABSORPTION IN INDIUM ANTIMONIDE, INDIUM ARSENIDE, AND GALLIUM ARSENIDE. ...

... Accession Number : AD0626747. Title : SIMULATED RAMAN EMISSION AND ABSORPTION SPECTROSCOPY. Descriptive Note : Status rept.,. ...

We consider the Raman amplification problem for silicon waveguides in the regime in which both the pump and signal pulses are relatively short but wide enough that their duration exceeds the phonon lifetime (about 3 ps in silicon). We use the coupled pump-signal equations for numerical simulations that include all competing nonlinear effects such as self- ...

A tutorial presentation is given of Raman scattering in crystals. The physical concepts are emphasized rather than the detailed mathematical formalism. Starting with an introduction to the concepts of phonons and conservation laws, the effects of photon-p...

The equations describing the stimulated Raman process, namely, the coupling equations of the laser light, the first Stokes light, the anti-Stokes light and the coherent phonon field are derived from the hamiltonians with the relaxation and dissipation ter...

... Title : Observation of Strongly Wavevector Dependent Raman Scattering by LO Phonons in GaAs Near the E sub 0 Gap. ...

The Raman effect due to phonons, Landau levels, and Stark ladder levels is analyzed theoretically. For the phonons, three mechanisms are identified, and their orders of magnitude are estimated for both Delta n = 1 and 2. The ratio of the intensities can b...

The triply degenerate q approximately = 0 optical phonons in diamond type crystals have even-parity and are Raman active and infrared inactive. The application of an electric field modifies the symmetry of the optical phonons and, thereby modifies the pol...

Multiphonon Raman scattering from LO phonons has previously been observed in CdS in the case where the laser frequency lies near the energy gap. The combined effects of finite wave vector and resonant energy denominators are offered as the explanation for...

A group-theory analysis of phonon symmetries in C60:I4 crystals is performed. The Raman spectra of various fullerites and shungites are investigated. This work is made within the program of Foundation for Intellectual Collaboration ``Fullerenes and Atomic Clusters'' supported by the Ministry of Science and Technical Policy of Russia.

Laser Raman spectroscopy shows that the photodimerization reaction of o-methoxy trans cinnamic acid crystal is mediated by a lattice phonon which softens with reaction progress.

The theory of exciton-enhanced Raman scattering is formulated in terms of the scattering of polaritons by optical phonons via the exciton part of the coupled modes. The expression for the exciton contribution to the scattering tensor is given, within a co...

The data for the Raman scattering intensity ratio of LO and TO phonons and its frequency dispersion are analyzed in terms of the atomic displacement contribution and the electro-optic contribution to the Raman scattering tensor. The theory of exciton-enha...

A sharp peak in the two-phonon Raman spectrum of diamond was first observed by Krishnan and has recently been shown to be at a frequency higher than twice the maximum single-phonon frequency by Solin and Ramdas. This peak is interpreted as evidence for th...

that a typical Stokes Raman spectrum consists of one LO and one transverse-optical (TO) phonon peaks at 743.8 cm scattering of the pump pulses by two LO phonons [3]. On the other hand, the anti-Stokes Raman spectrumResonant Raman scattering of coherent picosecond pulses by one and two ...

An interesting phonon mode at around 685-705 cm-1 was clearly observed in the Raman spectra of InGaN/GaN multiple-quantum-wells nanopillars with different diameters at room temperature. The Raman peak position of this mode is found to show a distinct dependence on the nanopillar size, which is in well agreement with theoretical ...

... ARSENIDES, FOURIER ANALYSIS, RESONANCE, ACOUSTICS, PHONONS, MODULATION, RAMAN SPECTRA, SPECTRA, ALUMINUM ...

... Infra-red and raman spectra of solids and liquids: This report reviews results obtained in this laboratory on the phonon spectra of a wide range of ...

... It has also been observed that one of the phonon modes shifts in going from the yttrium aluminum to the ytterbium aluminum garnet compound and ...

A new model is proposed to understand multi-phonon Raman spectrum (MRS) of II-VI semiconductors. A quasibound state of exciton-LO phonon complex (EPQBS) in the intermediate state is shown to be responsible for the observed overtone series. The observation...

Photoluminescence (PL) of single-walled carbon nanotubes (SWNTs) has been widely used for the measurement of chirality distribution of single-walled carbon nanotubes (SWNTs). However, there are unassigned peaks in the 2-D photoluminescence map plotted as a function of emission and excitation photon energy. In order to clarify the origin of these peaks, we have studied photoluminescence (PL) and ...

. The temperature depen- dence of the two-phonon contribution to the total Raman spectrum has been analyzed, respectively.15,16 The strong contribution of the two-phonon band to the total Raman spectrum has been of the Raman spectrum in the 700�1600 cm-1 wavenumber region below RT and above ...

spectrum of a sample with two absorption bands. Raman spectra are shown that are excited at a wave- length from resonance Raman spec- troscopy. The absorption spectrum is shown for a sample with two absorption different analytes in the sam- ple, we selectively enhance the vibrational ...

... radiation field. The resulting optical absorption is very strong at the frequencies of the transverse optical modes. Direct absorption ...

The report summarizes work in the areas of the optical and surface properties of perfect and imperfect crystals. It has resulted in theories of raman and Brillouin scattering of light, and infrared absorption, by phonons in metal surfaces: it has yielded first principles calculations of the microscopic crystal tensors governing these ...

The techniques of deep level derivative absorption spectroscopy (DLDAS), photoinduced-transients-spectroscopy (P.I.T.S.) were employed to study deep levels and interfaces in Ga As. Optical transitions due to impurities and structural imperfections where observed by (DLDAS) which can be correlated with levels observed by (P.I.I.S.). Raman measurements were ...

The peculinrities are inveatigated of the absorption of ultrasound in superconductors, which are associated with two mechanisms of phonon scattering: absorption of the phonon by an electron and the decay of a phonon into a pair of quasi-particles. It is shown that the derivative of ihe ...

We demonstrate excitation of transverse-optical (TO) phonons in a strained-Si on insulator (SSOI) by using a high-numerical-aperture oil-immersion lens. Using this technique, the TO phonons are excited, even under the (001) Si backscattering configuration. The wave numbers of the TO phonons in SSOI thus excited are different from that ...

We provide a topological understanding of the phonon Hall effect in dielectrics with Raman spin-phonon coupling. A general expression for phonon Hall conductivity is obtained in terms of the Berry curvature of band structures. We find a nonmonotonic behavior of phonon Hall conductivity as a ...

We study the thermal distribution of intervalley phonons in a graphene sheet. These phonons have two components with the same frequency. The degeneracy of the two modes is preserved by weak electron-phonon coupling. A sufficiently strong electron-phonon coupling, however, can result in a splitting into an optical ...

The Lyman spectrum of substitutional boron acceptors in diamonds with natural composition and that in a 13C diamond exhibit remarkably similar features, but shifted to higher energies in the latter by 0.4-1.5 meV. Additional lines appear when the spectra are recorded as a function of temperature, indicating the thermal population of a level ?'~2 meV above the ground state; this can be interpreted ...

The double resonance Raman spectra of the overtone of the out-of-plane tangential optical (oTO) phonon and of combinations of the LO, ZO, and ZA phonons with one another are calculated for bilayer graphene. In the case of the bilayer graphene, these Raman peaks are observed in the energy region between 1600 and ...

The prospects for realizing efficient nanoparticle light emitters in the visible/near IR for communications and bio-medical applications have benefited from progress in chemical fabrication of nanoparticles. III-V semiconductor nanopaticles such as GaP and InP are promising materials for the development of "blue" and "green" emitters, respectively, due to their large effective bandgaps. Enhanced ...

The Raman spectra of two G-bands and a radial breathing mode (RBM) of unfilled and filled single-wall semiconducting and metallic carbon nanotubes have been investigated in the presence of electron-phonon and phonon-phonon interactions. Excitation of low frequency optical plasmons in the metallic nanotube is shown to be responsible for ...

We have measured nonresonant and resonant Raman-scattering spectra from ZnO nanocrystals with an average diameter of 20 nm. Based on our experimental data and comparison with the recently developed theory, we show that the observed shifts of the polar optical-phonon peaks in the resonant Raman spectra are not related to the spatial ...

ZnS: Mn2+ nanoparticles have been prepared in aqueous media by using colloidal method, where environmental friendly Thio-Glycolic Acid (TGA) was used as a stabilizer. By TEM images nanoparticles of size approx. 2-3 nm was observed, which was confirmed by Debey Scherrer estimation from X-ray diffraction pattern (to be around 2.5 nm). UV-Visible absorption spectra reveal blue ...

The polarization of the Raman Spectrum of BaTiO3 was studied for different scattering geometries. The frequencies and symmetries of most of the Raman active pure symmetry phonons were determined. A transverse mode with E1 symmetry was found in the vicinit...

Laser Raman spectroscopy was used to identify the crystal structures of lanthanide and actinide compounds. The phonon Raman spectrum is characteristic of the particular crystal structure. GdCl sub 3 exhibits two crystal structures, the UCl sub 3 -type hex...

Resonance Raman scattering in semiconductors with indirect band gaps has been investigated in order to manifest the contribution of the iterative electron-one phonon process to second-order Raman scattering. The authors have searched without success for R...

We have presented a theoretical calculation of the differential cross section (DCS) for the electron Raman scattering (ERS) process associated with surface optical (SO) phonon modes in a semiconductor quantized spherical film. We consider the Fr�hlich electron-phonon interaction in the framework of the dielectric continuum approach. ...

An acoustic nanocavity can confine phonons in such a way that they act like electrons in an atom. By combining two of these phononic-atoms, it is possible to form a phononic 'molecule', with acoustic modes that are similar to the electronic states in a hydrogen molecule. We report Raman scattering ...

materials, (iiii) phonon recycling in lasers, and (iv) phonon-assisted photon absorption in photovoltaics. The theoretical treatments include ab initio and molecular dynamic...

The phenomenological theory of light scattering by optical and acoustical phonons is reviewed. The resonance enhancement of Brillouin scattering by acoustical phonons in the vicinity of the intrinsic absorption edge is related to the enhancement of the el...

... quantum dots; two-phonon processes in photon absorption; phonon effects on carrier transport in nanowires, including wurtzite-based nanowires ...

ELECTRON-PHONON INTERACTION ON OPTICAL SPECTRA OF NANOELECTRONIC DEVICES - Q. Kim. WAVELENGTB Q". Figure 1. Typical surface absorption ...

In this article, we report on the visible absorption, photoluminescence (PL), and fast PL decay dynamics from freestanding Si nanocrystals (NCs) that are anisotropically strained. Direct evidence of strain-induced dislocations is shown from high-resolution transmission electron microscopy images. Si NCs with sizes in the range of approximately 5-40 nm show size-dependent ...

A theory is presented of the optical absorption associated with current carriers which are bound to impurities in semiconductors in high magnetic fields and which interact with longitudinal optical phonons. The optical absorption coefficient is expressed ...

This work describes further development of the confinement theory used for fitting of the Raman-spectroscopy signal obtained from nanostructured materials. We present a simple algebraic method for the incorporation of an anisotropic phonon-dispersion function into the phonon confinement model. The anisotropy is shown to have particular ...

The general technique of light scattering and luminescence was used to study the properties of a number of material systems. First, multi-phonon resonant Raman scattering up to four phonons in GaSe and one- and two-phonon resonant Raman scattering in the mixed GaS/sub x/Se/sub 1-x/ crystals ...

The authors present here a microscopic theory to explain phonon anomaly in Raman active phonons of the cuprates R{sub 2{minus}x}M{sub x}CuO{sub 4} in normal state. They used electronic Hamiltonian of Fulde in presence of antiferromagnetism. They incorporated phonon interaction to the hybridization between the ...

Micro-Raman scattering and its temperature dependencies have been used to investigate lattice dynamic properties of ?-FeSi2 thin films epitaxially grown on Si (111) substrates by sputtering at elevated temperatures. A linear correlation between the blueshift in phonon energies and the lattice expansions in the growth direction of ?-FeSi2 is observed. The ...

We report ab initio calculations of the electronic band structure, the corresponding optical spectra, and the phonon dispersion relations of trigonal ?-HgS (cinnabar). The calculated dielectric functions are compared with unpublished optical measurements by [Zallen (unpublished)] The phonon dispersion relations are used to calculate the temperature and ...

We use a novel double microcavity for double optical resonant Raman amplification. The observed four orders of magnitude Raman enhancement is exploited to study finite size effects on the phonon spectra of GaAs/AlAs MQWs. The design allows almost backscattering geometries, thus providing easy access to the excitations in-plane ...

Raman spectra were excited with the red and yellow lines of a Kr+ laser at low temperatures in ZnTe single crystals doped with Li (Zn), P (Te), and As (Te) acceptors. LO phonons bound to neutral impurities were clearly observed in the spectra of Li- and P-doped samples, and their temperature and polarization behavior were investigated. As expected for a ...

We calculate low-frequency Raman scattering from the confined acoustic phonon modes of CdS(1-x)Se(x) nanoparticles embedded in borosilicate glass. The calculation of the Raman scattering by acoustic phonons in nanoparticles has been performed by using third-order perturbation theory. The deformation potential ...

To probe carrier-phonon interactions, population dynamics of non-equilibrium optical phonons and optical phonon self-energy effects have been studied in intrinsic and p-doped crystalline germanium on a picosecond time scale. Time-integrated, incoherent Raman scattering measurements from longitudinal optical ...

Resonant enhancement of selective pairs of phonons has been observed by noting the changes in the lineshape of the two-phonon Raman spectrum from Si and GaP as the incident photon energy is made resonant with the indirect energy gap. These selective phono...

to the sideband power created by each acoustic mode and are thus suitable for comparison with the measuredRaman-like light scattering from acoustic phonons in photonic crystal fiber P. Dainese* , P. St processes that take place when light is resonantly scattered by, respectively, optical and acoustic phonons

The Raman-active phonons in eight different aluminum, gallium, and iron garnet crystals have been investigated. The energies and symmetries of phonons in YbAlG, YbGaG, LuAlG, and LuGaG, as well as DyIG, ErIg, YbIG, and YIG, have been determined. Owing to ...

The authors present data on Raman scattering by optical phonons propagating at an angle to the ferroelectric axis in tetragonal BaTiO3 which correspond to coupled A1 and E symmetry phonons. The data show that the strongly damped 'soft' E symmetry optical ...

The metastability of a recently proposed candidate for a polymeric structure of nitrogen is confirmed by using linear response theory to calculate the phonon dispersion throughout the Brillouin zone. It is found that the structure is mechanically stable for pressures below at least 360 GPa. Calculations of Raman and infrared-active ...

The precipitation and growth of copper nanoparticles in an optically transparent aluminosilicate glass matrix was investigated. The size of particles in this heterophase glass-based composite was modified in a controlled manner by isothermal heat treatments. A multitechnique approach, consisting of Raman scattering spectroscopy, high-resolution transmission electron ...

Nanostructured CdS thin films synthesized by chemical bath deposition method were implanted with Cu+ ions at the doses of 5�1014, 1�1015 and 5�1015 ions/cm2. The grain size of the as-prepared samples as observed from the HRTEM images was �6 nm. The UV-Visible absorption and Raman spectra of as-prepared and Cu+ ion implanted samples were recorded. ...

The effect of pressure and temperature on the Raman-active phonon mode of osmium metal has been investigated for pressures up to 20 GPa and temperatures in the range 10-300 K. Under hydrostatic conditions (He pressure medium) the phonon frequency increases at a rate of 0.73(5)cm?1/GPa (T=300K) . A large temperature-induced and ...

We investigate the optical phonons in AlN nanotips using Raman spectroscopy. Apart from the group theoretically allowed optical phonons, an additional phonon mode at 850 cm-1 has been observed. Furthermore, the peak position has shown a significant redshift and its intensity increases dramatically with the change ...

Glycerol-passivated 3C-SiC nanocrystal (NC) solid films with tunable blue photoluminescence show abnormal longitudinal optical (LO) phonon behavior. As the NC size increases, the LO phonon intensity increases in the Raman spectra of the solid films and is even larger than that of the transverse optical mode. The ...

Micro-Raman spectroscopy is employed to study the phonon confinement in Au- and Mn-catalyzed GaAs and InAs nanowires. The phonon confinement model is used to fit the LO phonon peaks, which also takes into account the contribution to the asymmetry of the line shape due to the presence of surface optical (SO) ...

Performing polarized reflectivity and absorption measurements in the experimental range 15-1500 cm-1, we have investigated the infrared activity of phonons in aluminum phosphate. We report both ?2 (E?c) and ?3 (E?c) polarized components and, in order to identify all modes predicted by group theory arguments, we compare with similar measurements performed ...

Coupled magnon-phonon excitations in magnetic materials have been observed in multiferroic materials and involve the polar optical phonons. Such excitations may be more general, occurring in non-ferroelectric magnets and involving non-polar (Raman or silent) phonons. Temperature-dependent Raman ...

We use double optical resonant Raman amplification in a semiconductor microcavity to study the acoustical phonon spectra of GaAs/AlAs superlattices made of only a few periods. Besides the four orders of magnitude Raman scattering enhancement, the design allows the simultaneous collection of backward and forward-scattering ...

The Raman features of nanostructures are dependent of their sizes due to the small size effect. This has been confirmed by many observations, for example, the observation on the correlation between the size of Si-, and C- nano-structure and their Raman frequencies. But we also observed strangely that Raman frequencies of single- and ...

May 1, 2011 ... Fiber Raman Amplifier Development for Laser Absorption Spectroscopy Measurements ... power narrow linewidth fiber Raman amplifier for the ...

This dissertation describes a three part research effort on diamond films, monolayers, and polymers. The first part addresses the surface, interface, and bulk properties of the CVD (chemical vapor deposition) thin films using techniques such as XPS (X-ray photoelectron spectroscopy), SEM (scanning electron microscopy), FTIR-ATR (Fourier transform infrared-attenuated total reflection), spectra ...

We study the thermal distribution of phonons in a honeycomb lattice. Due to the two electronic bands there are two out-of-plane phonon modes with respect to the two sublattices. One of these modes undergoes an Ising transition by spontaneously breaking the sublattice symmetry. We calculate the critical point, the renormalization of the ...

The generation of a nonequilibrium population of optical phonons by photoexcited hot electrons in semiconductor quantum wells is investigated theoretically. The microscopic model of electron-phonon interaction proposed by Huang and Zhu has been used to compute the distributions of confined longitudinal optical phonons and interface ...

Resonant Raman scattering for one single wall carbon nanotube spectroscopy is overviewed. First-order resonance Raman spectra of the radial breathing mode of one carbon nanotube is of importance for assigning (n,m) values to the nanotube. This assignment of (n,m) values is confirmed by the chirality dependence of other phonon modes. ...

Relaxation of hot carriers excited by subpicosecond laser pulses has been studied by Raman scattering in GaAs/AlAs multiple quantum wells with well widths varying between 100 and 1000 {Angstrom}. The hot phonon population observed by Raman scattering is found to decrease with the well width despite the fact that the hot electron ...

The authors consider theoretically and experimentally how an extended van Hove singularity manifests itself in electronic and phonon Raman scattering in superconducting cuprates. The analysis and experimental data shows that in the case of singularity carriers redistribution between different parts of the Brillouin zone and/or electronic bands is a common ...

... Title : Elastic Scattering, Absorption, and Surface-Enhanced Raman Scattering by Concentric Spheres Comprised of a Metallic and a Dielectric ...

Nov 12, 2001 ... Combination Laser Absorption and Raman IR Spectrometer (CLARIS) for in situ Atmospheric, Particulate, & Mineralogical Studies of Mars ...

Temperature dependences of phase velocity and absorption of ultrasound were investigated in ZnSe crystal doped with Cr2+ ions at the frequencies 32-158MHz . Absorption peak and variation of phase velocity found in the temperature interval 10-20K were interpreted as manifestation of the Jahn-Teller effect. Temperature dependences of relaxation time, ...

This thesis presents a study of the phonons and related properties in two sets of nitride compounds, whose properties are until now relatively poorly known. The Zn-IV-N2 group of compounds with the group IV elements Si, Ge and Sn, form a series analogous to the well known III-N nitride series with group III element Al, Ga, In. Structurally, they can be derived by doubling the ...

... Title : Resonant Exciton-Phonon Spectra in ZnCdSe/ZnSe Single QW: Raman Scattering and Hot Luminescence; Extended and Localized Excitons. ...

... Phonons in wurtzite (GaN) m(A1N) , superlattices: non-monotoneous dependence of the number of Raman-active modes on superlattice period ...

... Title : Phonons in Wurtzite (GaN) mu(AIN) nu Superlattices: Non-Monotoneous Dependence of the Number of Raman-Active Modes on Superlattice ...

... Title : PHONON OPTICAL PROPERTIES OF MIXED FLUORITE SYSTEMS: RAMAN SCATTERING FROM Ca(1-x)Sr(x)F2 AND Ba(1-x)Sr(x)F2. ...

Raman spectroscopy provides nondestructive information about nanoscaled semiconductors by modeling the phonon confinement effect. However, the Raman spectrum is also sensitive to the temperature, which can mix with the size effects borrowing the interpretation of the Raman spectrum. We present an analysis of the ...

The Raman scattering spectra of lithium tantalate crystals with different compositions were investigated. The comparison of the Raman data obtained for the congruent and the near-stoichiometric crystals reveals some differences in the shape and the number of Raman peaks, which lead to a new assignment of the long-wavelength optical ...

The Raman spectra of numerous dodecaborides have been measured on high-quality single crystals at ambient conditions with high spectral resolution and signal-to-noise ratio. Besides the strong Raman-active modes, numerous Raman-inactive modes occur in the spectra, indicating distortions of the structures. Ab initio calculation of the ...

The Raman spectra of numerous dodecaborides have been measured on high-quality single crystals at ambient conditions with high spectral resolution and signal-to-noise ratio. Besides the strong Raman-active modes, numerous Raman-inactive modes occur in the spectra, indicating distortions of the structures. Ab initio calculation of the ...

CaSiAl and SrSiAl both crystallize in a hexagonal structure derived from MgB2 by substituting Ca/Sr for Mg and Si/Al for B. They both are superconductors, but superconducting properties differe substantially between two materials. It is possible that partial ordering of Si and Al plays a role in superconductivity. Raman scattering is a good tool to investigate this, because in ...

Here we report a temperature-dependent Raman study of the pyrochlore "dynamic spin-ice" compound Pr2Sn2O7 and compare the results with its non-pyrochlore (monoclinic) counterpart Pr2Ti2O7. In addition to phonon modes, we observe two bands associated with electronic Raman scattering involving crystal field transitions in Pr2Sn2O7 at ...

Lines that overlap from thermal broadening in the room-temperature Raman spectrum of gadolinium molybdate are resolved in the 80$sup 0$K spectrum. A total of 126 of the possible 201 lines have been resolved. Symmetry assignments are derived from considerations of both point symmetry and polariton dispersion, supported by separate measurements of A$sub 1$(TO) and ...

A theoretical explanation is given for the following paramagnetic phenomena caused by spin-phonon interaction: (1) absorption of the energy of an alternating magnetic field parallel to a constant field; (2) absorption of acoustic energy in a paramagnetic ...

The residual lattice absorption of GaAs in the three and four phonon regime is measured over a range of temperatures. The spectra reveal persistent structural features which are interpreted theoretically in terms of phonon density of states effects. (Auth...

The influence of exciton-phonon interaction on the shape of the light absorption band is studied by the method of retarded Green's functions. The specific choice made of the exciton-phonon interaction model makes it possible to obtain finite expressions f...

Raman spectra are acquired from Si nanowires (NWs) with diameters of 2-15 nm oxidized for different time durations. The Si TO optical phonon peak downshifts asymmetrically finally becoming an amorphous Si peak after a long oxidation time. The spectral changes cannot be correlated using the phonon confinement model of cylindrical NWs. ...

Ordered LiMgAs (space group: F-43m), viewed theoretically as a zinc-blende-AlAs-like (MgAs)- lattice partially filled with He-like Li+ interstitials, is studied using a Raman-scattering method. The band gap of as-grown crystals is found to be 2.309 eV with a direct gap from the photoluminescence measurements at 20 K, in consistency with that estimated by the optical ...

Extended X-ray Absorption Fine Structure and Raman studies were performed to follow the structural and vibrational behavior of a mechanical alloyed Ni{sub 25}Se{sub 75} mixture, containing nanocrystalline pyrite NiSe{sub 2} phase, when exposed to high-pressure conditions. An increase in the local structural order of the nanocrystalline phase with pressure ...

... concentration is well established, the occurrence of self-absorption (defined as absorption of Raman scattered photons by the sample itself) ... known to cause problems. The influence of self-absorption i...

... SHIFT, ABSORPTION, PHONONS, DISPERSION RELATIONS, ATOMIC PROPERTIES, ALKALI METALS, ALKALINE EARTH METALS, NICKEL. ...

... to stationary effects of the ion-vibration interaction ... MAGNETIC MATERIALS, IONS, CHROMIUM, VANADIUM, PHONONS, ABSORPTION ...

We report here the microscopic theory of the Raman spectra of the colossal magnetoresistive (CMR) manganite systems. The system is described by a model Hamiltonian consisting of the double exchange interaction in addition to the charge ordering interaction in the e(g) band and spin-spin interaction among the t(2g) core electrons. Further the phonon ...

The method of zone folding is applied to the calculation of the phonon mode frequencies in carbon nanotubules. The Raman and infrared-active mode frequencies are determined for nanotubules of different diameters and chiralities.

... ZnSe Single QW: Raman Scattering and Hot Luminescence; Extended and Localized Excitons DISTRIBUTION: Approved ...

Raman spectra of monoclinic hafnium oxide (HfO2) were measured at temperatures up to 1100 K. Raman peak shifts and broadenings are reported. Phonon dynamics calculations were performed with the shell model to obtain the total and partial phonon density of states, and to identify the individual motions of Hf and O ...

... Research was focused in two areas: 1. Using excite-and-probe anti-Stokes Raman scattering apparatus, the nonequili- brium phonons which ...

... Identify by block number) GaAs Hetrostructures; Sdperlatti ces, uasiperiodic Structures,-Raman Scattering, Optical Properties, Acoustic Phonons, ,{'i ...

.R.Bowle GROUND STATE MINIMUM Density of Electronic States b Initio imulation MEDEA PHONON IR and RAMAN activities

... Raman scattering; Phase transitions(Structural); Improper ferroelectricity; Incommensurate phase transitions, Rare earth molybdates; Phonons. ...

A detailed investigation of temperature-dependent micro-Raman scattering has been carried out on AlInN films with different Al compositions (0-0.53). The observed phonon frequency downshift and linewidth broadening with increasing temperature can be well explained by a model taking into account the contributions of the thermal expansion, the ...

Hexagonal YbMnO(3) bulk polycrystals were prepared and studied by Raman scattering in the temperature range of 15-300�K. A total of 15 phonon modes of A(1), E(1) and E(2) type were identified. Some E(2) phonon modes showed anomalous temperature variations in frequency at T(N)?80�K, suggesting a coupling between the spin and ...

In this letter, using both off-resonant and resonant Raman spectroscopic techniques, the correlation of optical phonons and structural disorder in As{sup +} implanted ZnO single crystals has been investigated. An additional broad peak shoulder at 550 cm{sup -1} between the transverse optical and longitudinal optical (LO) phonons was ...

We report ab initio calculations of the phonon spectra for hafnium nitride (HfN) at ambient and high pressures. The calculation of phonon density of states using the density functional perturbation theory including external perturbations like strains and electric fields in periodic systems carried out for full Brillouin zone. The lattice constant obtained ...

We report the ultrafast dynamics of the coherent A{sub 1g} and E{sub g} phonons of antimony as a function of temperature and optical polarization. Like in bismuth, the two phonon modes exhibit nearly {pi}/2 difference in their initial phase, suggesting their different coupling strengths with photoexcited electrons. The dependence of the ...

The authors applied the photomodulation spectroscopy for probe-photon energies from 0.05 to 2.5 eV in films of ladder-type poly(p-phenylene) and identified a photoinduced absorption (PA) band related to triplet excitons and two correlated PA bands due to charged polarons. The low energy polaron band peaks at a relatively low photon energy of {approximately}0.1 eV, showing ...

Nanostructured CdS thin films were deposited on glass substrates by chemical bath deposition technique. RBS and SEM analyses showed that the film surface was smooth, consisting of uniformly dispersed clusters. Absorption spectra of as prepared sample showed a blue shift in the absorption edge indicating quantum confinement effect. The band gap of the N+ ...

Far-infrared transmittance measurements are performed on a series of isotopically labeled samples of the quasi-one-dimensional solids [Pt(en)2][Pt(en2X2][ClO4]4, (en)=ethylenediamine and X=Cl, Br, or I. Pronounced shifts upon deuteration of the (en) ligands reveal that several absorption features previously attributed to localized vibrational modes of chain defects are in fact ...

Abstract. Photoinduced IR absorption measurements are reported on WO3. A photoinduced midinfrared small polaron peak centered at 4800 cm ?1 (0.59 eV) was observed. The data were analyzed in the framework of the photon-assisted small-polaron hopping theory and briefly compared to previously published infrared absorption measurements in WO3 and photoinduced ...

Electron paramagnetic resonance (EPR) measurements of LiNbO3: Yb, Pr (0.8wt.%, 0.1 wt.%) single crystals were analyzed for lattice sites of Yb in the crystal and also for the Yb3+ pairs arising. Parameters of the spin Hamiltonian were calculated using EPRNMR program. From the angular variations of the EPR spectra it results Yb3+ ions of C1 symmetry arise in the crystal. Pr3+ ions change parameters ...

Nonlinear quantum phonon excitations are studied in 1D lattice models for both effective nonlinear phonon and coupled electron-phonon systems. Multi-phonon bound states exist which are eigenstates of the system Hamiltonian, and which are natural counterparts of breather solutions of classical nonlinear systems. ...

Resonant Raman spectroscopy is realized on closely spaced nanowire-based quantum wells. Phonon quantization consistent with 2.4-nm-thick quantum wells is observed, in agreement with cross-section transmission electron microscopy measurements and photoluminescence experiments. The creation of a high-density plasma within the quantized structures is ...

Isotope-induced scattering of optical phonons in individual single-walled carbon nanotubes (SWNTs) was investigated by resonance Raman scattering measurements of more than 600 suspended, isotope-mixed SWNTs. The G+ and G- features in the SWNT G-band exhibit broadening of up to 80% and 25%, respectively, indicating a reduced lifetime of the corresponding ...

Nonequilibrium populations of both confined and interface phonons generated by picosecond laser pulses in a series of GaAs/AlAs quantum wells have been studied by time-resolved picosecond Raman scattering as a function of well width. The dependence of the nonequilibrium phonon populations on well width is found to be sensitive to the ...

The temperature dependence of the frequencies and linewidths of the Raman-active longitudinal optical (LO) phonons in GaAs and AlAs have been measured. The low-temperature lifetime of the LO phonon in AlAs is found to be 9.7 ps, very close to the corresponding GaAs value of 9.5 ps. This contradicts early theoretical predictions. The ...

Cesium thiomolybdate, Cs{sub 2}MoS{sub 4}, has been investigated at pressures up to 12 GPa. Two phase transitions have been detected by absorption measurements, Raman spectroscopy, and energy dispersive x-ray diffraction. The first phase transition to a monoclinic phase II [a=14.061(9) {Angstrom}, b=11.552(7) {Angstrom}, c=9.852(6) {Angstrom}, ...

History and recent developments of terahertz devices utilizing lattice and molecular vibration are presented. In particular, semiconductor Raman oscillator and amplifier, parametric generation of terahertz wave using polariton-phonons in dielectrics and semiconductors are discussed, together with future important applications in the field of medicine, ...

... TITLE: Raman and Hot Electron-Neutral Acceptor Luminescence Studies of Electron-Optical Phonon Interactions in GaAs/Al[x]Ga[lx]As Quantum ...

Contents: Infrared and raman spectra of solids; Pressure dependence of infrared and raman spectra of solids; Polymorphism of solids, hardness and other physical properties; Long-wavelength optical phonons in mixed crystals; Impurity induced lattice vibrat...

The review deals with the interaction of electromagnetic radiation with phonons or the vibrational modes of a solid. In particular, infrared transmission, reflection and Raman scattering spectra originating from the lattice vibrations of non-metallic soli...

The experimental observation of the hyper-Raman scattering of light by hot polaritons excited by frequency-tunable CO2-laser radiation is reported. This made it possible to increase the scattering intensity by several orders of magnitude and to investigate polariton line profiles.

... polarized optical rectification (OR) signals * Background Raman signal (p-polarized ... Raman background -60 0 60 120 150 240 300 azimuthal angle ...

The authors observe electric field induced Raman scattering from longitudinal optical phonons in CdS. The induced scattering, observed in diagonal polarization for frequencies near the exciton peak, is superimposed on wavevector dependent scattering. The ...

It is possible to induce infrared and Raman activity in a crystal by the application of an external force which lowers the symmetry of the vibrational modes of the crystal. The authors present a group theoretical analysis of the effects of a strain gradie...

The technique of Raman Scattering has proved to be a powerful means of examining optical vibrations in the depletion layer associated with the surface of semiconductors. In particular, in doped InSb and GaAs, one observes a line in the Raman spectrum at t...

Hyper-Raman scattering by the zone-centre optical phonons in some alkali halides is investigated. In our calculations we relate the electrooptic part of the hyper-Raman tensor to the third-order optical susceptibility and the electric field associated wit...

Multiferroic Bi1-xSmxFeO3 (x = 0.00, 0.05, 0.1, 0.15, 0.2) ceramics were prepared by conventional solid state reaction method. X-ray diffraction measurement was carried out to characterize the crystal structure and to detect the impurities existing in these ceramics. The substitution of rare earth Sm for Bi was found to decrease the impurity phase in BiFeO3 ceramics. There is strong evidence that ...

... Title : Room Temperature Exciton Absorption, Excitonic Nonlinearities, and Exciton-Phonon Interaction in (Zn,Cd)Se/ZnSe Quantum Wells,. ...

Relative matrix elements are calculated for the absorption coefficient in the indirect-absorption-edge region for uniaxially stressed silicon. The calculations are for , , and stress, for all possible phonons, for all independent polarizat...

... IONS, METALS, MOLECULES, ELECTRODES, CYANIDES, ABSORPTION, ROUGHNESS, SILVER, THIOCYANATES, FATTY ACIDS ...

Samples, representing Si matrix with nanoformations of the semiconducting silicides beta-FeSi2 and Mg2Si are studied by Raman scattering. The unpolarized Raman spectra of the samples are interpreted in the framework of the appearance of interface-phonon polaritons. The theoretical dispersion relations of the ...

A tutorial presentation is given of Raman scattering in crystals. The physical concepts are emphasized rather than the detailed mathematical formalism. Starting with an introduction to the concepts of phonons and conservation laws, the effects of photon-phonon interactions are presented. This interaction concept is shown for a simple ...

We present a systematic study of the Raman spectra of optical phonons in graphene monolayers under tunable uniaxial tensile stress. Both the G and 2D bands exhibit significant red shifts. The G band splits into 2 distinct subbands (G(+), G(-)) because of the strain-induced symmetry breaking. Raman scattering from the G(+) and G(-) ...

Hyper-Raman scattering by the zone-center optical phonons in some alkali halides is investigated. In our calculations we relate the electrooptic part of the hyper-Raman tensor to the third-order optical susceptibility and the electric field associated with the LO phonons. The result obtained for those alkali ...

The processes underlying the inverse Raman effect are qualitatively described by comparing it to the more familiar phenomena of conventional and stimulated Raman scattering. An experession is derived for the inverse Raman absorption coefficient, and its r...

Highly dispersed ZnO quantum dots (QDs) in polyvinylpyrrolidone (PVP) nanotubes have been prepared by a single capillary electrospinning. The structure and optical properties characterizations were performed by x-ray diffraction, scanning and transmission electron microscopy, absorption, photoluminescence, and resonant Raman spectra. In the composites, PVP ...

The nonlinear interaction of zero sound with the order parameter collective modes in superfluid {sup 3}He-B is considered within perturbation theory in the amplitude of the sound field. Selection rules for nonlinear excitation of the order parameter modes are determined by the approximate particle-hole symmetry of the {sup 3}He Fermi liquid. A diagrammatic algorithm, based on the quasiclassical ...

The chalcopyrite structure can be viewed as two sphalerite unit cells stacked along (001) with reduction of symmetry from F43m to 142d. The contents of the primative cells increases from one AX to two ABX/sub 2/. Direct factor group calculations give T/sub 2/ (IR + Raman) for sphalerite and A/sub 1/ (Raman) + 2 A/sub 2/ (-) + 3 B/sub 1/ ...

630. THE RAMAN SPECTRUM OF GALLIUM PHOSPHIDE By R. S. KRISHNAN and N. KRISHNAMURTHY, Department Raman spectrum of GaP has been interpreted by these authors with the r, L and X critical point phonon structure whose vibration spectrum ba- sed on the Raman lattice dynamics has already (1) Voir communication

structure in the Raman spectrum of Nad, KBr, and NaI in terms of phonon pairs at X, L, and A symmetry points.e., the selection rules for the second order Raman spectrum are quite favourable, where as Article published online of the second order Raman spectrum was carried out by Narayanan [13] who reported 5 peaks. ...

to create strongly enhanced Raman excitation in a region just a few nanometres across. The tapered waveguide. In this case, the expected theoretical field enhancement was $100 (Raman enhancement $1 � 108 ). The AFM�Raman nanocrystal/SiOx surface. a, Three-dimensional map of the Raman signal at 520 cm21 (c-Si ...

different models for the fullerene Raman spectrum and the results of Raman measure- ments on ethane-0 Countless experiments have used Raman spectroscopy to identify the vibrational spectrum of molecules to give a good fit to the C60 IR and Raman vibrational spectrum. Next, the phonon ...

This thesis presents two topics related to the optical properties of III-V quaternary alloys. The first topic is the Raman scattering of the mixed alloys and the second topic is the measurement of the bandgap by linear optical methods. Chapter 3 describes the Raman scattering results for rm Al_{x}Ga _{0.5-x}In_{0.5}P, rm Ga_{x}In_{1 -x}As_{y}Sb_{1-y} , rm ...

The Raman spectra, infrared spectra and upconversion luminescence spectra were studied, and the effect mechanism of OH{sup -} groups on the upconversion luminescence of Er{sup 3+}-doped oxyhalide tellurite glasses was analyzed. The results show that the phonon energy of lead chloride tellurite (PCT) glass was lower than that of lead fluoride tellurite ...

We present a novel technique that intrinsically mitigates the quantum-defect heating in Raman lasers. The basic principle of this so-called �coherent anti-Stokes Raman scattering (CARS)-based heat mitigation� is to suppress the phonon creation in the Raman medium by increasing the number of out-coupled ...

A problem confronted in the study of phonons is the detection. The absorption of phonons by optically excited metastable states has proven to be of considerable use. An excellent example, known as the ruby spectrometer, is provided by the (sup 2)E states ...

We have investigated the spectral and temporal dynamics associated with phonon decay in the YAG:Pr3+ system at a range of temperature between 9 and 25 K. Nonequilibrium phonons were generated using defect induced one phonon absorption (DlOPA) of far infra...

A piezospectroscopic investigation of the normalized wave-length-modulated absorption spectra of the phonon-assisted indirect exciton in Si (TO-phonon) and Ge (LA phonon) at 77 deg K has yielded values for the ratio of the electron-phonon to the hole-phon...

Self-organised Ge quantum dot (QD) superlattices having properties of two and zero dimensional structures were investigated by Raman spectroscopy. Longitudinal optical Ge (LO) and Ge-Si (L) phonons and folded acoustic (LA) phonons superimposed with a stro...

We present a study of the optical phonon spectrum of relaxed In{sub x}Al{sub 1-x}As epitaxial layers grown by molecular-beam epitaxy on GaAs substrates in the whole range of In content (x = 0 divide 1) using macro- and micro-Raman and IR spectroscopies.