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MP24

Code: MP24	Time Slot/Poster Number: 146	Session: Solid State, Semiconductors and Nanoparticles
Zricaloy-4 high temperature oxidation and nitriding in air – A Raman imaging study
Isabel Idarraga^{1, 2}; Michel Mermoux²; Christian Duriez¹; Alexandre Crisci⁴; Jean-Paul Mardon³
¹IRSN, Cadarache, France; ²LEPMI, Grenoble, France; ³Areva, Lyon, France; ⁴SIMaP, Grenoble, France

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Summary
In nuclear plants, some accidental situations can result in air exposure of fuel assemblies. At high temperature, the combined action of oxygen and nitrogen will lead to fast degradation of the zirconium alloy fuel claddings. To better understand the mechanism of this degradation and the exact role of nitrogen, data on composition, microstructure and crystallography of zirconia layers formed in air at high temperature are required. In this study, Raman spectroscopy and Raman imaging have been used to characterize oxide layers formed on Zircaloy-4 cladding exposed to air at temperatures between 800 and 1000°C.

Code: MP24	Time Slot/Poster Number: 135	Session: Solid State, Semiconductors and Nanoparticles I
A Study of Aggregation Structure in Low Dimension Non-Crystal Silicate by Low Wavenumber Raman Spectrum
Rubi Li; Peicang Xu
Home, Changzhou, China

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Summary
In this paper，the aggregation size in the low dimension non-crystal silicate samples synthesizing via high temperature melting and sol gel methods have been studied by small-angle x-ray scattering (SAXS),transition electron microscopy (TEM) and low wavenumber Raman spectrum(LWRS). It is formed that the aggregation size (Ls values) is in inverse proportion to the vibration frequency of phonics phonon like mode and the aggregation size (Ls) of M series is large than the Ls of G series. It is indicated that the network-scale of high temperature melting quenched glass phase is large than the network-scale of low temperature gel.

Code: MP24	Time Slot/Poster Number: 136	Session: Solid State, Semiconductors and Nanoparticles I
Vibrational Study of Plasmon Effect in Photocatalytic Degradation of Congo Red and the Adsorption Mechanisms on Catalyst
Daniela Tristão^{1, 2}; Michele Souza^{1, 2}; Paola Corio^{1, 2}
¹, São Paulo, Brazil; ²Chemistry Institute, University of São Paulo, São Paulo, Brazil

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Summary
In the present work, the effect of silver nanoparticles (Ag NPs) on mechanism and kinetics process of photocatalytic degradation of CR with commercial TiO2 (Degussa P25) and nanostructured TiO2 synthesized in laboratory (nanoTiO2)3 was studied. Raman spectroscopy was applied to the understanding of the nature of the chemical interaction between the catalyst surface and the dye, which is important information to achieve an understanding of the kinetic mechanisms in heterogeneous photocatalysis.

Code: MP24	Time Slot/Poster Number: 137	Session: Solid State, Semiconductors and Nanoparticles I
The influence of temperature on Ag(nu1) Raman mode in NaBrO3 crystal
Petr Zverev
General Physics Institute RAS, Moscow, Russian Federation

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Summary
The results on spontaneous Raman spectroscopy of SRS-active vibronic modes in NaBrO3 crystal in the 15÷300 K temperature range are presented. Mode broadening and frequency shift of with crystal temperature are investigated. The relaxation mechanisms for Ag(nu1) vibronic mode are proposed.

Code: MP24	Time Slot/Poster Number: 138	Session: Solid State, Semiconductors and Nanoparticles I
Phase Transition In Perovskite LaGaO3 Crystals Doped With Sr And Mn : Studied By Raman Spectroscopy
Tomasz Runka¹; Michal Glowacki²; Marek Berkowski²; Miroslaw Drozdowski¹
¹Poznan University of Technology, Poznan, Poland; ²Institute of Physics, Polish Academy of Sciences, Warszawa, Poland

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Summary
The micro-Raman spectroscopy investigations were performed for La1-xSrxGa1-yMnyO3 crystals. Single crystals were grown by the Czochralski method from the melt with compositions: La1-xSrxGa1-yMnyO3, x = 0.05 y = 0.06, x = 0.075 y = 0.09 and x = 0.1 y = 0.12. Temperature measurements of crystals with composition La0.95Sr0.05Ga0.94Mn0.04O3 and La0.925Sr0.075Ga0.91Mn0.09O3 prove the existence of phase transitions at about 336 and 280K, respectively.

Code: MP24	Time Slot/Poster Number: 139	Session: Solid State, Semiconductors and Nanoparticles I
Temperature and Pressure Dependent Spectra of Raman Scattering at Resonantly Tuned Exciton States in 2H-MoS2
Tsachi Livneh; Eran Sterer
Department of Physics NRCN, Beer-Sheva , Israel

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Summary
The temperature and pressure dependence of Stokes and anti-Stokes Raman spectra of 2H-MoS2 as the energies of the A1 and B1 excitons, EA1 and EB1, are tuned to resonate with an exciting laser at EL=1.96 eV. Pressure and temperature dependent intensity ratio analysis of the resonant A1g phonon and the E12g phonon is complemented by the calculation of resonance Raman probability profiles, which well agree with experiments. The temperature dependent proximity of EA1 and EB1 to EL is reflected in the formation of Stokes dominated A1 and anti-Stokes dominated B1 temperature “zones” with a mid-point around T =260 K

Code: MP24	Time Slot/Poster Number: 140	Session: Solid State, Semiconductors and Nanoparticles I
Vibrational Dynamics Of YPO4 And ScPO4 Single Crystals: An Integrated Study By Polarized Raman Scattering Experiments And Simulations.
Marco Giarola¹; Andrea Sanson¹; Atowar Rahman¹; Barbara Rossi¹; Marco Bettinelli¹; Adolfo Speghini¹; Enzo Cazzanelli²; Gino Mariotto¹
¹University of Verona, Verona, Italy; ²University of Calabria, Cosenza, Italy

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Summary
A detailed vibrational dynamics study was performed on crystalline YPO4 and ScPO4 , by using both Raman spectroscopy and first principles calculations. Through a proper polarization analysis all the allowed 12 Raman modes were selected in turn, and assigned in symmetry. The Raman modes of both YPO4 and ScPO4 single crystal have been calculated by density functional theory (DFT) within the generalized gradient approximation. CRYSTAL code package has been used for simulation. The calculated wavenumbers of the 12 Raman active modes were found in good agreement with our experimental data, thus definitively supporting our experimental results.

Code: MP24	Time Slot/Poster Number: 141	Session: Solid State, Semiconductors and Nanoparticles I
Combined Raman Scattering and Optical Transmission on AlGaN Thin Films with Variable Flow Rates of Trimethylindium
Y.L. Chung¹; T.Y. Lin¹; Zhe C. Feng¹; D.S. Wuu³; I. Ferguson²; W. Lu⁴
¹National Taiwan University, Taipei, Taiwan; ²University of North Carolina, Boulevard Charlotte, USA; ³National Chung Hsing University, Taichung , Taiwan; ⁴Fisk University, Nashville, USA

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Summary
AlGaN epilayers were grown on sapphire substrates by Metal Organic Chemical Vapor Deposition (MOCVD), in order to improve the surface morphology and the film quality, variable flow rates of trimethylindium (TMIn) were introduced during the growth for the incorporation of indium. Rutherford backscattering (RBS) was used to measure the composition of AlxGa1-xN(x~0.16) thin films. Here, we report the changes via Raman scattering (RS), photoluminescence (PL) and optical transmission (OT), revealing optical properties of AlGaN with variable indium flow rates.

Code: MP24	Time Slot/Poster Number: 142	Session: Solid State, Semiconductors and Nanoparticles I
High Temperature Raman Spectrum of Phonon Vibration Like Modes for Aggregation Structure in Silicate Melts
Peicang Xu; Rubi Li
home, Changzhou, CHINA

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Summary
In this paper，the vibration frequency of phonon like mode in the low dimension silicate series synthesizing via high temperature melting method have been measured by means of low wavenumber Raman spectrum(LWRS) and high temperature Raman spectrum(HTRS).The nanometer self-similarity aggregation structure(it’s size is about a few nm to dozens of nm) and phonics phonon vibration like modes have been obtained. The results showed that the aggregation size of the silicate melts is smaller at high temperature than at room temperature and the number of bridge oxygen for one Si-O tetrahedron in network structure units is decreasing at high temperature.

Code: MP24	Time Slot/Poster Number: 143	Session: Solid State, Semiconductors and Nanoparticles I
Raman spectra and polymorphism in N-benzyl-2-methyl-4-nitroaniline
Katarzyna Piela¹; Ilona Turowska-Tyrk¹; Marek Drozd²; M. Magdalena Szostak¹
¹Institute of Physical and Theoretical Chemistry, Wrocław, Poland; ²Institute of Low Temp. and Structural Research, Wrocław, Poland

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Summary
In this work we present structural and Raman spectroscopic studies on the new optically nonlinear organic molecular crystal, N-benzyl-2-methyl-4-nitroaniline (BNA) with “push-pull” system and high efficiency of second harmonic generation (SHG). The goal of our investigations is to recognize the origin of BNA optical nonlinearity thus intermolecular interactions, electron transfer, polymorphism and phase transitions are taking into account. The effect of phase transitions on the normal modes of vibrations in crystals is important in order to understand the molecular dynamic in optically nonlinear BNA. Particularly, the differences in lattice vibration modes will be discussed.

Code: MP24	Time Slot/Poster Number: 144	Session: Solid State, Semiconductors and Nanoparticles I
High Temperature Raman Spectra and Ge-O Coordination Study of Sodium Germanates
Wang Yuanyuan
Shanghai University, Shanghai, China

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Summary
Germanates are applied in fiber-optics, activater, infrared optical material et al as important functional materials. Understanding the microstructure of melts relevant to their macro physical and chemical properties is important. The Ge-O coordination of pure GeO2, Na2Ge4O9 and Na4Ge9O20 crystals from 273 to 1373 K are studied by high temperature Raman spectroscopy.The result showes that a conversion in the coordination number of Ge-O 6 to 4 in Ge(Ⅵ)-containing rutile GeO2, Na2Ge4O9 and Na4Ge9O20 crystals was commonly observed and NBO was formed with increasing temperature. There is only Ge(Ⅳ) in pure GeO2 and sodium germanates melts.

Code: MP24	Time Slot/Poster Number: 145	Session: Solid State, Semiconductors and Nanoparticles I
Micro Raman Study of La substituted BiFeO3 Films
Pramod S Dobal¹; Ram S Katiyar²
¹V S S D College, Kanpur, India; ²University of Puerto Rico, San Juan, PR 00931 USA

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Summary
There has been increasing interest in BiFeO3 multiferroics ever since their potential was realized in the emerging fields of spintronics, information storage and sensors. Despite the fact that investigation of phonons has played a great role in the understanding of classical ferroelectrics, the phonon behavior is yet to be established in multiferroics. In this work Polarized Raman spectra from undoped as well as La-substituted BiFeO3 thin films formed by sol-gel solutions on SRO/STO substrates are presented. Temperature dependent Raman spectra are used to determine the variation of transition temperature with La addition in BiFeO3 lattice.

Code: MP24	Time Slot/Poster Number: 147	Session: Solid State, Semiconductors and Nanoparticles I
Sub-Second Tracing of Lattice Mode Changes During the Melting of an Anthracene Crystal
Hajime Okajima¹; Hiro-o Hamaguchi^{1, 2}
¹the University of Tokyo, Tokyo, Japan; ²National Chiao Tung University, Hsinchu, Taiwan

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Summary
We applied the fast low frequency Raman spectroscopy to the sub-second tracing of the rapid melting of an anthracene crystal. The low frequency Raman spectral change is continuously measured in 0.2 seconds for each spectrum. The loss of the lattice vibrational Raman bands is clearly observed. From the anti-Stokes/Stokes intensity ratio of the lattice vibration bands, the sample temperatures are accurately estimated. It is found that the temperature of the crystal becomes transiently higher than the melting point. It indicates the existence of a transient “super-heated” crystal, in which the crystal structure around the molecule locally remains.

Code: MP24	Time Slot/Poster Number: 148	Session: Solid State, Semiconductors and Nanoparticles I
Stimulated Low-FrequencyRaman Scattering in Nanostructured Materials
Anna Kudryavtseva¹; Valeriy Savranskiy²; Nikolay Tcherniega¹
¹Lebedev Physical Institute, RAS, Moscow, Russia; ²Prokhorov General Physics Institute, RAS, Moscow, Russia

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Summary
Low-frequency stimulated Raman scattering with frequency shift from exciting light in GHz range has been observed in the following materials: synthetic opal matrices, nanocomposites on their base (opal matrices infiltrated with different nonlinear liquids), nanostructured thin films (polycluster diamond films, alumunium nitride films, indium tin oxide films) and suspensions, consisting of detonation nanodiamond particles in water. Stimulated scattering is a result of a ruby laser 20-nanosecond pulses interaction with acoustic vibrations of the studied materials structure elements. Frequency shifts have been measured for different material composition and different experimental conditions.

Code: MP24	Time Slot/Poster Number: 149	Session: Solid State, Semiconductors and Nanoparticles I
Resonant Raman scattering of MgZnO thin films grown on sapphire by MOCVD
Chih Cheng Wei¹; Yu Li Tu¹; Zhe C. Feng¹; Chia Cheng Wu²; Po Rung Lin²; Dong Sing Wuu²
¹National Taiwan University, Taipei, Taiwan; ²National Chung Hsing University, Taichung, Taiwan

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Summary
MgZnO materials with wurtzite structure were grown on sapphire substrate by Metal-Organic Chemical Vapor Deposition. Samples with five different composition of x(Mg) from 0 to 0.14 were studied. As increasing the Mg-composition, the X-ray diffraction signal of MgZnO (101) is getting stronger, besides MgZnO (002). The gap energy and composition of MgZnO can be determined from optical transmittance measurements. Combined ultraviolet photoluminescence and Raman scattering were measured with PL-Raman signals obtained together, showing a blue-shift of PL band and variation of resonant Raman multi-order longitudinal optical phonon modes with an increase of x(Mg).

Code: MP24	Time Slot/Poster Number: 150	Session: Solid State, Semiconductors and Nanoparticles I
Polarization-Dependent Raman Characterization of Stibnite (Sb2S3)
Paolo Sereni¹; Maurizio Musso¹; Peter Knoll²; Karlheinz Schwarz³; Günther Schmidt³; Peter Blaha³
¹University of Salzburg, Salzburg, Austria; ²University of Graz, Graz, Austria; ³Vienna University of Technology, Vienna, Austria

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Summary
Two sets of polarization-dependent Raman spectroscopic measurements have been performed on single crystal samples of Stibnite (Sb2S3), a naturally occurring sulfide mineral with semiconducting properties and an energy band gap of approximately 1.72 eV, using both a visible and an infrared laser excitation line (532 and 1064 nm, respectively), and the results have been compared with density functional theory calculations.

Code: MP24	Time Slot/Poster Number: 151	Session: Solid State, Semiconductors and Nanoparticles I
Determination of Single Microcrystalline Silicon Grains Preferential Crystallographic Orientation by Polarized Raman spectroscopy
Martin Ledinsky; Aliaksei Vetushka; Jiri Stuchlik; Antonin Fejfar; Jan Kocka
Institute of Physics, Academy of Sciences of the C, Prague 6, Czech Republic

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Summary
Thin films of microcrystalline silicon (μc-Si:H) are intensively studied mainly for thin film solar cells. Structural and material properties of μc-Si:H significantly depend on the crystalline volume fraction and the crystallographic orientation of the grains. Polarized Raman spectroscopy may be used for determination of crystallographic orientation of single μc-Si:H grains. Comparison of the measured and by the theory determined polarization ratio allowed us to conclude that small grains in μc-Si:H were randomly oriented.

Code: MP24	Time Slot/Poster Number: 152	Session: Solid State, Semiconductors and Nanoparticles I
Raman and FTIR studies on chalcogenide glasses
Theodore Ganetsos¹; Yannis Skarlatos²; Bill Kotsos¹; Nikos Laskaris¹
¹TEI of Lamia, Lamia, Greece; ²Bogazici University, Physics Department, Istanbul, Turkey

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Summary
Investigation of amorphous and crystalline regions of chalcogenide glasses is of practical interest for obtaining new materials with semiconducting properties. They have potential applications in infrared region due to their heavy elemental masses, continuous variation of band gap-energies and lattice constants as well as electrical properties, with compositions. To understand the nature of the electronic processes, it is necessary first of all to investigate their optical properties and the phenomena of charge carrier transfer in such materials. Accordingly, FTIR and Raman Spectroscopy measurements in chalcogenide glasses and conductivity measurements as function of temperature are presented in this research work.