Abstract: The incorporation of small molecular weight active agents into polymeric matrixes bearing controlled release characteristics represents an interesting strategy with numerous useful applications. Antimicrobials, biocides, fungicides or drugs, encapsulated into erodible or non-erodible polymeric micro-spheres, micro-capsules and micro-shells or/and embedded into continuous polymeric matrixes, are controlled released either by particular degradation routes or/and by specific stimuli. Cross-linking, curing or micro-porosity generating agents acting during polymerization impart additional controlled encapsulation characteristics to the active substances. Release modulating agents, like retardants or carrier materials used as vehicles are often encapsulated into microspheres or dispersed within polymeric compositions for the controlled introduction of an active agent into a liquid-based media. The aim of this review is to reveal relevant strategies reported in recent patents on the encapsulation or incorporation of low molecular weight active agents into the matrix of polymers bearing controlled release characteristics. The inventions described implicate the formation of both erodible and non erodible polymer microparticles that contain active ingredients. Modification of the polymer matrix and inorganic porous carriers represent pertinent major strategies that have been also developed and patented.

Abstract: In this work we have examined whether the re-impregnation of CoMo/γ-alumina catalysts or the replacement of the conventional non-dry impregnation step by ��equilibrium deposition filtration�� (EDF) may be used for improving their surface characteristics and thus their catalytic activity. Two samples were prepared. In the first sample (EDF) the molybdenum species were mounted by ��equilibrium deposition filtration�� whereas in the second sample these species were mounted by non-dry impregnation (NDI). In both cases the Co was deposited on the calcined Mo/γ-Al2O3 precursor solid by simple dry impregnation. An aliquot of each sample was impregnated again with an amount of pure water equal to its pore volume and then it underwent drying and calcination. The catalysts prepared were characterized using N2 adsorption measurements (BET), UV�vis diffuse reflectance spectroscopy (DRS), laser Raman spectroscopy (LRS) and NO chemisorption. The hydrodesulfurization (HDS) activities over the catalysts studied were determined using a continuous-flow tubular fixed-bed microreactor operating in a differential mode at atmospheric pressure. It was confirmed that the replacement of the conventional impregnation by equilibrium deposition filtration results to catalysts with relatively high active surface and high portion of the well-dispersed octahedral cobalt and thus, to catalysts with 30% higher HDS activity. The reimpregnation resulted to partial dissolution and re-dispersion of the Mo and Co supported oxidic phases. Concerning the NDI catalyst reimpregnation resulted to an increase of the active surface and of the portion of the well-dispersed octahedral cobalt and thus to 25% higher catalytic activity. The opposite effects were observed for the EDF catalyst which exhibited almost 7% lower activity after re-impregnation.

Abstract: One-component samples containing K, Ni, and various concentrations of Mo were prepared by incipient wetness impregnation technique. Bi and tri- component samples have been prepared from the calcined one- and bi-component samples following the same procedure. The samples were characterized by SSA, FT-IR, DRS and Raman measurements. The decrease of the ratio Ni2+(Td)/Ni2+(Oh) with the increase of Mo loading and the re-dispersion of Mo phase after the Ni addition on the onecomponent Mo containing samples proved the occurrence of interactions between these components in the bi-component NiMo-containing samples. Most probably Ni�Mo�O surface species with different number of Mo-oxo and Ni-oxo entities are formed, depending on the Ni/Mo atomic ratio. It may be accepted, that the Ni2+ ions are partially localized into the molybdate layer without forming well-defined phases. Two kinds of K+ ions have been determined in the corresponding samples, interacting (��bounded�� K+ ions) and not interacting (��free�� K+ ions) with the rest of the supported phases. The potassium deposition increased the dispersion of Mo phase and influenced the coordination state of the Mo6+ and Ni2+ ions in the bicomponent KMo-, KNi-containing samples and the tri-component KNiMo-containing samples. It provoked partial transformation of the polymeric Mo6+(Oh) species into monomeric Mo6+(Td) ones and Ni2+(Td) species predomination over Ni2+(Oh) ones. Most probably, new complex K�Ni�Mo�O species were formed on the support surface in the case of the tri-component samples.

Abstract: This paper examines the growth of ZnO structures on Si (1 0 0) using the aqueous chemical growth (ACG) technique for deposition times of between 1 and 40 h. It is found that ZnO grown using zinc nitrate hexahydrate (Zn(NO3)2 6H2O) and hexamethylenetetramine (HMTA) as precursors at 95 1C exhibits single-phase wurtzite ZnO crystal structure. The shape and the dimensions of the structures were found to depend on the growth time. The results are discussed in terms of kinetic studies carried out in correlation with the different deposition periods.

Abstract: This study examines the application of an improved non-contact and non-invasive Raman spectroscopic technique in measuring medicines at therapeutic concentrations in a model system mimicking the anterior chamber of the eye. A 90o laser Raman scattering geometry is employed to reduce the direct exposure of the basic cordial ocular tissues to the laser beam and increase the signal to noise ratio of the spectra. The technique is applied to a commercially available artificial anterior chamber (AAC) fitted with corneas of porcine eyes. Specific Raman signatures of ciprofloxacin (Ciproxin®), a fluoroquinolone based antibiotic, have been resolved. Finally, a PLS chemometric algorithm has been developed to predict the concentration of ciprofloxacin in AAC over the range from 0 to 1 mg/mL with a correlation coefficient R2=98.4% and an RMS error of prediction equal to 41 μg/mL.

Abstract: Nafion� perfluorosulfonic acid (PFSA) polymer electrolyte membranes were uniaxially drawn at a temperature where the a-relaxation is active. Polarized UV-Raman spectra revealed the anisotropy developed. They strongly suggest that upon uniaxial drawing, Nafion macromolecular chains are oriented parallel to the drawing axis, while the perfluorinated side chains exhibit a tendency to be oriented perpendicular to the draw axis. The drawing process resulted to the reduction of the membrane thickness in addition to an enhanced mechanical strength along the draw direction, measured with Dynamic Mechanical Analysis. In a parallel study, a preliminary molecular orientation study of uniaxially drawn Teflon samples allowed a better assignment of the Raman bands of Nafion.

Abstract: An investigation of the effect of the deposition pressure (133.3�1333 Pa) on the μc-Si:H crystallinity, stress and thermal stability was performed. The films were deposited from SiH4/H2 discharges under constant power conditions and with constant silane partial pressure. The increase of pressure resulted in an optimum of the deposition rate at 333.3 Pa and an increase of the crystallinity as the pressure is raised from 133.3 to 333.3 Pa. The Raman spectra revealed a shift of the c-Si peak for all films towards lower wave numbers and this shift was much larger for the film deposited at 133.3 Pa. The effect of film stress and local heating in this shift was distinguished by investigating the effect of temperature on the position of the c-Si peak. The stress of the deposited films was found to be tensile for all pressures and much higher for the film deposited at 133.3 Pa. This result is discussed in terms of the deposition conditions pointing out the advantages of working at higher pressures.

Abstract: We report on an inelastic (Raman) light scattering study of the local structure of amorphous GeTe (a-GeTe) films. A detailed analysis of the temperaturereduced Raman spectra has shown that appreciable structural changes occur as a function of temperature. These changes involve modifications of atomic arrangements such as to facilitate the rapid amorphous to crystal transformation, which is the major advantage of phase-change materials used in optical data storage media. A particular structural model, supported by polarization analysis, is proposedwhich is compatiblewith the experimental data as regards both the structure of a-GeTe and the crystallization transition. The remarkable difference between the Raman spectrum of the crystal and the glass can thus naturally be accounted for.

Abstract: Electrical relaxation and conductivity processes in amorphous and semicrystalline poly(ethylene terephthalate) (PET) and poly(ethylene naphthalate) (PEN) homopolymers and certain PET/PEN copolymers have been studied by means of dielectric spectroscopy. Homopolymers and copolymers able to crystallize were subjected to successive thermal runs to investigate the influence of the thermal history upon the morphology and the electrical behavior of the polymeric systems. The morphology of the untreated as well as the heat-treated specimens was determined by means of Differential Scanning Calorimetry (DSC). All samples exhibit β-relaxation process, due to local motions of the C=O polar side groups, and a-relaxation process associated to the glass/rubber transition. In the PEN spectrum an additional, subglass, mode was recorded, most probably attributed to cooperative motions of the naphthalene groups. Finally, the dynamic nature of the crystallization process is expressed via the over glass transition mode and the temperature dependence of dc conductivity recorded in amorphous PET, PEN, and PET/PEN (85/15) (wt/wt) samples.

Abstract: Background and Objectives: Laser Raman spectroscopy is an inelastic light scattering technique able to characterize molecules in aqueous environments. The purpose of this work is to develop a non-contact and non-invasive spectroscopic method to identify and eventually quantify the presence of medicines (e.g. antibiotics) and physiological substances (e.g. glucose) in the aqueous humor of the eye. Study design/Materials and Methods: A new laser light delivery probe has been developed and adapted to a Raman spectroscopic system with the ability of favorable collection of the Raman light at 90o scattering geometry while scanning the anterior chamber of the eye. Different amounts of ceftazidime, amphotericin b and glucose had been injected in the aqueous humor of porcine eyes, max. 24 hours after death and extraction, in-vitro. Raman measurements were excited with a visible (514,5-nm) laser beam at a power of 25-mW and an exposure/acquisition time of 1-sec. Results: The specific collection optics and Raman analysis components used in the present work have resolved the Raman signatures of probed molecules and low concentrations of ceftazidime (0.9-mg/mL), amphotericin b (9-μg/mL) and glucose (2-mg/mL) separately injected in the anterior chamber of porcine eyes were detected in vitro. Conclusion: This special illumination design gives the opportunity of avoiding the direct exposure to the laser light of basic cordial tissues of the eye, like lens and retina, although an optimum collection of scattered light is accomplished. Concentrations close to the minimum inhibitory concentration (MIC) have been detected for ceftazidime and amphotericin b; the detection of glucose has been realized at concentrations close to the early pathological levels of patients with diabetes.

Abstract: PET and PBT samples uniaxially drawn above Tg and beyond the yield point exhibit significant differences in their molecular orientation behavior, as probed by polarized Raman spectra. The quasi-amorphous PET samples, drawn close to the Tg, manifest considerable molecular orientation development; however, when drawn above Tg+30oC, they exhibit significant molecular orientation relaxation. The semi-crystalline PBT samples maintain prominent molecular orientation even when drawn 110oC above Tg. The drawing process, in PET samples, when resulting in molecular orientation, is accompanied by a gauche-trans transformation of the glycol linkage and a concurrent initiation of crystallinity development. In PBT specimens, it gives rise to a coexistence of α and β type crystalline phases. Phase α is predominant at high draw temperatures, i.e. Tg+110oC, while phase β dominates at low draw temperatures, i.e. Tg+10oC. PBT samples, with β-phase predominance, left at relevant draw temperatures without stress, exhibit a β-α phase-change though no molecular orientation relaxation occurs. A note is made of the fact that complete molecular orientation analysis of PBT segments utilizing the depol method gives more reliable results than the simplified analysis assuming cylindrical tensor for the 1614-cm-1 symmetric stretch of the para- disubstituted benzene ring of PBT. In this context, segments of PBT specimens rich in α-phase exhibit higher molecular orientation than those with β-phase predominance.

Abstract: The effect of the total SiH4/H2 gas pressure (1�10 Torr) on the growth rate, the film crystallinity and the nature of hydrogen bonding of microcrystalline silicon thin films deposited by 13.56MHz plasma-enhanced chemical vapour deposition (PECVD) was investigated under well-controlled discharge conditions. The deposition rate presents an optimum for 2.5 Torr, which does not follow the trend of silane consumption that increases with pressure and is attributed to an increase in plasma density. The film crystallinity increases with pressure from 1�2.5 Torr and then remains almost the same, whereas the films deposited at 1 Torr are highly stressed. On the other hand, hydrogen bonding is also drastically affected.

Abstract: A new method of controlled release of low molecular weight biocides incorporated in polymer matrixes is described. The molecular orientation of uniaxially drawn biocide doped polymer films is suggested as a significant parameter for controlled release monitoring. Triclosan, a well-established widespread antibacterial agent, has been incorporated into high density polyethylene (HDPE) films that have been subsequently uniaxially drawn at different draw ratios. The molecular orientation developed was estimated utilizing polarized μ-Raman spectra. Biocide incorporated polymer films, drawn at different draw ratios, have been immersed in ethanol-water solutions (EtOH) and in physiological saline. The release of Triclosan out of the polymer matrix was probed with UV-Vis absorption spectroscopy for a period of time up to 15 months. In all cases, although the film surface of the drawn samples exposed to the liquid solution was higher than the undrawn one, the relevant release rate from the drawn specimens was lower than the non-stretched samples depending on the molecular orientation developed during the drawing process. A note is made of the fact that no significant molecular orientation relaxation of the polyethylene films has been observed even after such a long time of immersion of the drawn films in the liquid solutions.

Abstract: Triclosan and phosphonium salt biocides have been separately incorporated into Polystyrene-Divinylbenzene (PS-DVB) beads by suspension polymerization. Ultraviolet (UV) absorption measurements have been used to monitor the release of these low molecular weight biocides out of the PS-DVB beads immersed in water-ethanol mixtures and in physiological saline. The release of the biocide agents is strongly dependent on either the DVB or/and the antimicrobial composition ratio in the beads. An increasing of biocide incorporation in the PS/DVB beads was accompanied by a corresponding enhancement of its concentration in liquid mixtures. On the contrary, higher crosslinking densities hindered the biocide migration out of the beads by diminishing its release rate into either the aqueous ethanol solutions or the natural serum. Moreover, FT-Raman spectra and Attenuated Total Reflectance Infrared (�ΤR-FT�R) measurements of the PS-DVB-Triclosan and PS-DVB-Phosphonium salt beads, before and after their immersion in water-ethanol solutions, gave a similar qualitative evidence of the biocide release.

Abstract: A CoMo/γ -Al2O3 catalyst, prepared by depositing on the Al2O3 carrier first theMo species via equilibrium deposition filtration (EDF) and then the Co species by dry impregnation, was compared to three CoMo/γ -Al2O3 samples prepared using various conventional impregnation methods. All samples had the same composition, corresponding to an atomic ratio Co/(Co + Mo) equal to 0.3. The above samples were characterized using various physicochemical techniques (AAS, BET, DRS, LRS, XPS, TPR, and NO chemisorption), and their catalytic activity was determined using the hydrodesulfurization (HDS) of thiophene as a probe reaction. The EDF-prepared catalyst was about 30�43% more active in HDS than those prepared with the conventional impregnation techniques at all reaction temperatures studied. In contrast, the EDF catalyst exhibited the lowest hydrogenation activity. The higher HDS activity of the EDF sample is attributed to the higher number of active HDS sites formed on its surface. It is concluded that the increased number of active sites is due to the fact that the deposition of the Mo species by EDF results to a higher coverage of the support surface by supported molybdenum phase, which in turn, inhibits the formation of the catalytically inactive CoAl2O4 and favors the dispersion of octahedral cobalt on its surface.

Abstract: The wide use of titanium in applied materials has prompted pertinent studies targeting the requisite chemistry of that metal�s biological interactions. In order to understand such interactions as well as the requisite titanium aqueous speciation, we launched investigations on the synthesis and spectroscopic and structural characterization of Ti(IV) species with the physiological citric acid. Aqueous reactions of TiCl4 with citric acid in the presence of H2O2 and neutralizing ammonia afforded expediently the red crystalline material (NH4)4[Ti2(O2)2(C6H4O7)2]â2H2O (1). Complex 1 was further characterized by UV-vis, FT-IR, FT- and laser-Raman, NMR, and finally by X-ray crystallography. Compound 1 crystallizes in the monoclinic space group P21/n, with a ) 10.360(4) �, b ) 10.226(4) �, c ) 11.478(6) �, â ) 107.99(2)°, V ) 1156.6(9) �3, and Z ) 2. The X-ray structure of 1 reveals a dinuclear anionic complex containing a TiIV 2O2 core. In that central unit, two fully deprotonated citrate ligands are coordinated to the metal ions through their carboxylate moieties in a monodentate fashion. The central alkoxides serve as bridges to the two titanium ions. Also attached to the TiIV 2O2 core are two peroxo ligands each bound in a side-on fashion to the respective metal ions. NH4+ ions neutralize the 4- charge of the anion in 1, further contributing to the stability of the derived lattice through H-bond formation. The structural similarities and differences with congener vanadium-(V)-peroxo-citrate complexes may point out potential implications in the chemistry of titanium with physiological ligands, when the former is present in a biologically relevant medium.

Abstract: A new method is proposed for the estimation of the segmental orientation of vinyl or vinylidene polymers of moderate crystallinity by acquisition of only one Raman spectrum at a specific polarisation geometry. A highly anisotropic rigid rod or/and Resonant Raman-active guest-agent incorporated into a host-polymer can be easily detected at low concentration levels and be used as indicator of the molecular orientation of the processed host-polymer. A suitable polarised Raman measurement and the automatic calculation of the ratio of two Raman bands, one sensitive and another roughly non sensitive to the drawing process, may allow, via an appropriate calibration curve, a continuous on line molecular orientation monitoring of drawn vinyl and vinylidene polymers during an industrial process. Polymers of common use, like poly(vinyl chloride) (PVC), isotactic polypropylene (iPP) and poly(vinylidene fluoride) (PVF2), were selected for the application of the methodology in question. Promising results were derived utilising a new custom made flexible laser Raman instrumentation bearing a special designed polarised Raman micro-probe able to accumulate fast-polarised Raman spectra in all backscattering polarisation geometries.

Abstract: Polarized laser Raman microscopy was used to estimate the molecular orientation of uniaxially drawn films of mostly random copolymers of poly(ethylene 2,6-naphthalate) (PEN) and poly(ethylene terephthalate) (PET) as a function of the draw ratio. The Raman bands of the symmetric stretching modes of benzene and naphthalene rings at 1616 and 1636 cm-1 have been respectively used for PET and PEN segments orientation evaluation. Polarized Raman spectra obtained from PEN/PET films in the whole concentration range indicate that PET segments are better oriented in the copolymers than in the homopolymer attenuating the neck formation of PEN. Moreover, PEN/PET films stretched at temperatures 30oC higher than the corresponding glass transition temperatures exhibit different degrees of segmental relaxation depending on the dominant, PEN or PET, number average segment length. These relaxation discrepancies are accompanied by conformational changes of the ethylene moieties. In certain PEN/PET polymer mixtures, at specific window of stretching parameters, PEN segments exhibit comparable and even higher to homopolymer molecular orientation. Isotropic and drawn type films were both characterized by DSC, solution 1H-NMR, dynamic mechanical tensile measurements and FT-Raman spectroscopy.

Abstract: In this article we present the first quantitative estimates of the spectroscopically active part of the interaction potential in molten complex chlorides based on dephasing studies. We have selected the molten salt systems containing quasispherical complex MCl4-2 anions (M=Mn+2 and Zn+2) and performed the study of their ν1(A1) isotropic Raman line profiles as a function of the temperature and concentration. We have analyzed the form of the time correlation function of vibrational dephasing and determined the type of modulation events, which cause the line broadening processes in these systems; these are found to be purely discrete Markovian. Within the formalism of the purely discrete Markovian modulation, we have made a judgement about spectroscopically active interactions in these systems. Interionic potential in complex chlorides is dominated by the attraction forces, which depend on the interparticle distance r as r-4, and by repulsion of the r-7 -type.

Abstract: A two step synthetic procedure towards model coil-rod-coil triblock copolymers was developed. In the first step, a,x-bromo-functionalized oligophenylenes (rod part) were modified to anionic bifunctional initiators. In the second step, flexible chains were grown from both ends of the rod part by an anionic polymerization procedure leading to polystyrene-rod-polystyrene and/or poly(2-vinyl pyridine)-rod-poly(2-vinyl pyridine) triblock copolymers. Characterization of the final products by gel permeation chromatography, NMR spectroscopy, light scattering, Raman spectroscopy and differential scanning calorimetry demonstrated that well-defined coil-rod-coilblock copolymers can be synthesized.

Abstract: Miscibility in a series of blends, derived from Polyamide 11 (PA 11) and sulfonated polysulfone (SPSF) with different sulfonation degrees, 20, 44 and 70% has been investigated using differential scanning calorimetry, dynamic mechanical analysis, Fourier transform infra-red (FTIR) and Raman spectroscopy. The PA 11/SPSF(Na)x blends were prepared by solution casting from dimethyl formamide (DMF). Differential scanning calorimetry has shown a melting point depression of the equilibrium melting point of PA 11. From the melting point data of the blends of PA 11 with the SPSF with a 70% degree of sulfonation, the value of the polymer�polymer interaction parameter x 12 was found to be 21.1 at elevated temperatures where it was determined. Less negative values were obtained for the blends of SPSFs with lower degrees of sulfonation, indicating the role of the sodium sulfonate group to the observed miscibility. Dynamical mechanical analysis revealed a non single-phase system at lower temperatures, although the Tg of PA 11 phase is shifted to higher temperatures. FT-IR and FT-Raman spectroscopic techniques have been used to confirm the nature of the specific interactions involved.

Abstract: Micro-Raman spectroscopy is used to characterize the cemented product formed during cobalt cementation with zinc dust in zinc sulfate electrolytes. The effect of copper and antimony on the cementation process is also examined. A Raman spectrum characteristic of a basic cobalt salt or mixtures of such salts is observed. The spectrum is similar to those found for Co(OH)2 in a ZnO matrix. The main Raman band of this salt has a frequency at 550 cmy1. Raman mapping over a larger area, 1000=1000 mm, of cemented products shows that the occurrence of this peak decreases dramatically during re-dissolution of cemented cobalt. The data indicate that a large fraction of the cemented Co2+ exists as a mixture of cobalt containing oxide and hydroxide.

Abstract: Polybenzimidazole (PBI) and polysulfone (PSF) compose an immiscible polymer pair, the introduction however of functional groups such as sulfonate groups in the polymeric chain of PSF, resulted in the formation of miscible blends with PBI. The miscibility behavior of a series of blends of PBI with sulfonated PSF (SPSF) at various sulfonation levels has been studied by Dynamic Mechanical Analysis (DMA), FT-IR and FT-Raman spectroscopy. DMA has shown that sulfonation degree as well as blend composition controls the miscibility behavior of the studied system. In that respect, partially miscible or miscible blends were obtained when the sulfonation level is higher than 10% mol. Since both polymers exhibit functional groups, which could participate in specific interactions, this possibility has been examined by FT-IR analysis. In absorption FT-IR spectra of PBI-SPSF specimens with high sulfonation degree and high PBI content, band shifts associated with the NH and sulfonate groups are accounted for the induced miscibility in terms of specific interactions. Moreover, a clear red shift of the symmetric vibration of the main chain sulfone group at 1152 cm-1 has been also observed in the FT-Raman spectra of miscible PBI-SPSF blends. Careful examination of this spectral feature, assisted by curve fitting analysis, has revealed that, besides the peaks attributed to pure PBI and PSF, a new scattering contribution, which is accounted for a new associated type of sulfone group, appears as the sulfonation degree of SPSF is increasing. This was partially attributed in terms of specific interactions but also to the Raman sensitivity in the medium polarity changes related to the increase of blend homogeneity. Preliminary results have demonstrated the potential usefulness of the blend polymeric membranes as electrolytes for fuel cells.

Abstract: The molecular orientation of uniaxially drawn commercial poly(vinyl chloride), PVC, specimens has been investigated by polarized Fourier transform infrared (FTIR) in the specular reflectance mode and by resonance Raman scattering in various combinations of sample orientation, scattering configuration and polarization geometry. The orientation was examined as a function of the specimen draw ratio. The Kramers-Kronig transformation has been used to obtain infrared absorption spectra from the FTIR reflectance data; the orientation was determined by the dichroic ratio of the C-Cl stretching and CH2 rocking modes of PVC. The resonance Raman spectra of polyene segments, that result from partial thermal degradation/dehydrochlorination of PVC during processing, have been utilized in order to determine the parameters of the orientation distribution function. The all-trans conjugated polyene sequences formed during degradation are considered as rod-like segments in the polymer backbone and are used as indicators of orientation within the amorphous-like polymer phase. As the trends is concerned, data analysis showed good agreement between FTIR and Raman results regarding the induced molecular orientation in industrial PVC specimens.

Abstract: The structure of molybdenum and boron species in the ternary system (NaF-KF)- K2MoO4-B2O3 and the quasi binaries (NaF-KF) K2MoO4, (NaF-KF)-B2O3, K2MoO4-B2O3 were investigated by Raman(melts and solids) - and IR(solids) - spectroscopy. The Raman spectra of the melts show the MoO42- ion only in K2MoO4 containing melts. When B2O3 is added, the B2O3 network of the pure oxide is broken down and anions of the BO3F4- and BO2F23- types may form. These anions may play a crucial role in the MoO42- reduction mechanism by absorbing O2- ions liberated when molybdenum metal is depositing. Molybdenum in lower than 6+ oxidation states was not observed using the above methods. ESR studies, however, indicates Mo5+ in the pure oxide containing melts. The spectra of the fluoride containing melts and solids do not show heteropoly anions or oxide bridging molybdenum complexes. Such complexes have been suggested in the literature in order to explain the electroreduction of molybdate.

Abstract: A computational approach was elaborated to explicitly account for the Rayleigh line wing, the Boson peak and vibrational contributions to the low-frequency Raman spectra of amorphous solids and viscous liquids. It was shown that the low-frequency Raman spectra of glycerol and polystyrene consist of the Rayleigh contribution of Lorentzian form and the Boson peak which profile follows the predictions of the theory by Martin and Brenig in the version by Malinovsky and Sokolov. In the case of triacetin, the Boson peaks decay faster in their high-frequency side than the above theory predicts. Their form can be successfully modeled with a newly introduced empirical function intermediate between the Martin�Brenig and Malinovsky�Sokolov predictions.

Abstract: Raman spectra of dark brown-black ironIII. chloride melts have been obtained at 600 K using resonance and micro-Raman techniques. The main polarized bands seen in the spectra are at 310, 414 and 452 cmy1 and their relative intensities depend on the frequency of the laser excitation line. The data are interpreted to indicate that the predominant species in the melt are Fe2Cl6 bitetrahedral molecules plus charged molecular species which are formed according to the dissociation scheme:

Abstract: Chromia�vanadia on titania catalysts containing 8 mol% (Cr C V) were prepared and tested for the selective catalytic reduction (SCR) of NO by NH3, in excess O2, in the temperature range 250�450±C. The physicochemical properties of the prepared catalysts as well as those of the corresponding single active phasecontaining samples were investigated by specific surface area and pore volume measurements, X-ray powder analysis, UV�visible diffuse reflectance spectroscopy, laser-Raman microscopy, X-ray photoelectron spectroscopy, analytical electron microscopy, and temperature-programmed reduction experiments. The best catalytic performance was achieved by the catalyst containing 2 mol% Cr and 6 mol% V (TiCr2V6), while all the binary active phasecontaining catalysts proved to be more active than the corresponding single active phase-containing catalysts, at reaction temperatures higher than 350±C. The enhanced catalytic performance of the binary active phase-containing catalysts is attributed to a synergy developed between the two active phases. This synergy is maximized in the TiCr2V6 sample, where a new Raman band, at 971 cm¡1, has also been observed. This peak is attributed to isolated Cr6C species decorated by well-dispersed V5C species. Deposition of the chromia phase on the titania surface stabilizes the texture of the final catalysts against changes provoked by deposition of the vanadia phase.

Abstract: The structural properties of the cadmium species formed by dissolution of cadmium metal in molten cadmium halides (CdX X\Cl, Br, I) and in molten mixtures of cadmium chloride with alkali chlorides have been investigated by Raman spectroscopy. The data indicate that in these ionic solvents the predominant species present is the solvated Cd subvalent cation. With increasing ionic strength of the counter anion the frequency of the diatomic cation shifts from 158 cm~1 for the chloride melt to 183 cm~1 for the iodide melt. Due to the overlap of the electronic absorption edge of the Cd with the laser lines used to excite the spectra the Raman band intensities of the solute species are preresonance enhanced. The dissolution of cadmium metal in the cadmium chloride�alkali chloride mixtures increases with temperature and depends on the stability of the CdCl species formed in these melts. The looser the CdCl42~ association the higher the solubility and the stability of the Cd species. Raman spectroelectrochemical methods have been applied for studying amorphous carbon electrode surfaces during electrolysis of CdCl in LiCl-KCl eutectic. A new Raman band measured at D158 cm~1 during electrolysis was attributed to the subvalent Cd species. It seems that these species are formed in the vicinity of the electrode by a homogeneous electrochemical reaction.

Abstract: Polymeric films of rigid-flexible luminescent polyethers containing substituted quinquephenyl units in the main chain and films of their diluted blends in polypropylene have been uniaxially drawn at temperatures above their glass transition. Polarized micro-Raman measurements have been conducted to evaluate the molecular orientation of the drawn polymers and probe the effect of side chain length and type. The second, P2, and fourth, P4, moments of the segmental orientation distribution function determined from the analysis of Raman spectra indicate that the longer the side-chain length the higher the molecular orientation attained. At short side chain lengths, the presence of an oxygen link between the alkyl side chain and the aromatic segment resulted in a restricted polymer orientation. Polarized photoluminescence measurements have shown that neat photonic polyethers display low dichroic ratios despite the high orientability shown in Raman measurements. Diluted blends of photonic polyethers in polypropylene have shown commensurate high orientation moments in Raman and enhanced dichroic ratio in photoluminescence. The implication on the perspective of the studied polyethers to give materials with polarized blue light emission is evident.

Abstract: Based on a model correlation function which covers spatial correlations from Gaussian to exponential, we have arrived at an exact analytic solution of the problem of the Boson peak profile in amorphous media. Probe fits made for polyisoprene and triacetin prove the working ability of the formulae obtained.

Abstract: Raman spectroscopy has been used to elucidate the structure of molten iron(III) chloride and its binary mixtures with caesium chloride. In order to overcome difficulties arising from the dark coloration of these melts and to ensure the spectral features, both conventional resonance Raman and micro-Raman spectra have been obtained. The spectral changes upon melting the solids Cs2NaCl6, CsFeCl4 and FeCl3 have beenmeasured. The FeCl4- tetrahedra were found to be present in both the solid and molten CsFeCl4 ,while a change of coordination from six-fold (FeCl63-)to four-fold (FeCl4-)occurs upon melting Cs2NaFeCl6 .The FeCl4- tetrahedra are the predominant species in CsCl-FeCl3 mixtures containing up to 50 mol% FeCl3.The systematics and the temperature dependence of the spectra of the molten mixtures with mole fractions from 50 to 100 mol% FeCl3 indicate the presence of Fe2Cl7-, FeCl2+ and Fe2Cl5+ ionic species. Resonance Raman spectra of molten FeCl3 were measured and compared with the spectra of the corresponding solid and vapor. The data are interpreted to indicate a self-ionization of the molecular Fe2Cl6 melt::2Fe2Cl6=Fe2Cl5++Fe2Cl7- .The proposed model accounts for both the near-ionic conductivity of the melt and the structural data obtained by neutron diffraction.

Abstract: V2O5/TiO2 catalysts of varying vanadium content were prepared at various pH�s and concentrations of the impregnation solution using the equilibrium deposition filtration (EDF) method. Moreover, corresponding catalysts were prepared using the conventional wet impregnation (WI) method. The above catalysts were exhaustively characterized using BET, AEM, FT-IR, DRS, LRM, XPS, TPR, and TPD of NH3 and tested for the SCR of NO by NH3 in the temperature range 250-450° C. It was found that the application of EDF results in V2O5/TiO2 catalysts with relatively high dispersity of the vanadia supported phase, homogeneous distribution of this phase on the support particles, and quite strong interactions between the supported vanadia phase and the surface of titania, and inhibits the formation of supported V2O5 crystallites. The catalysts prepared by EDF exhibited better activity and selectivity than those prepared by conventional WI. Decrease of the impregnation pH in the EDF preparations from 8 to 4.5 caused an increase in the vanadium content from 2.6 to 3.6 wt % V2O5 which, in turn, provoked very important differences in the physicochemical properties of the EDF catalysts (increase of the surface coverage of the titania by the vanadia phase and decrease of the mean value of the vanadia phase-support interactions). The above explained the increase, with the vanadium content, of the activity and selectivity of the V2O5/TiO2 EDF catalysts.

Abstract: On the assumption that the stretching exponent value in the stretched exponential model is the same for both ν1 (Σ+) and ν3 (Σ+) vibrations of SCN-, an �additional" broadening of the ν1 line has been identified and attributed to dissipative losses due to ion�dipole interactions between cations and anions in melt.

Abstract: Polarized laser Raman microscopy was employed in order to investigate the effects of side chain length on the orientability of uniaxially drawn films of a model hairy-rod polymer, as a function of draw ratio; an aromatic polyester containing terphenyl units in the main chain and aliphatic side chains (hexyl and dodecyl units) was used in the experiments. The second and fourth moments of the segment orientation distribution function, P2 and P4, respectively, determined from the analysis of the Raman spectra, indicate that the polyester with longer (dodecyl) side chains clearly exhibits higher molecular orientation compared to the one with shorter (hexyl) side chains, for the same draw ratio. Complementary FTIR measurements provide detailed information on the segmental orientation and confirm the effects of side chain length in inducing orientation; the latter result strongly suggests that the longer aliphatic side chains are oriented toward the polyesteric main chain, much more effectively than the shorter ones, apparently due to their higher flexibility. Raman measurements at high wavenumbers corresponding to the CH2 and CH3 stretching modes of the aliphatic side chains corroborate this suggestion. Further evidence comes from independent measurements of optical anisotropy of p-phenylene oligomers bearing hexyl and dodecyl side chains. The implications to the processing of hairy polymers are evident.

Abstract: Chromia on titania catalysts containing chromium loading ranged from 0 up to 8 mol% Cr have been prepared and calcined at high temperature (500±C). These catalysts have been tested for the selective catalytic reduction of NO by NH3 in excess of O2 at relatively high reaction temperatures (250�450±C). The physicochemical properties of the prepared samples have been investigated by specific surface area and pore volume measurements, X-ray powder analysis, UV-visible diffuse reflectance spectroscopy, laser-Raman microscopy, X-ray photoelectron spectroscopy, analytical electron microscopy, and temperature programmed reduction experiments. The best catalytic performance has been found for the catalyst containing the lowest amount of active phase (2 mol% Cr). The relatively high catalytic performance of this catalyst has been attributed to the isolated Cr(vi) surface species strongly interacting with the anatase surface. In fact the physicochemical characterization mentioned above showed that these species are predominant at this low Cr-loading. Increase in the Cr-loading has been found to favor the formation of badly dispersed chromia phases with lower oxidation states. Besides the title reaction, the direct oxidation of NH3 by O2 and the reaction of NH3 with NO producing N2O take also place at intermediate reaction temperatures (250�350±C). At elevated reaction temperatures (400�450±C) the direct oxidation of NH3 was found to be significant.

Abstract: Raman and UV/VIS spectra were obtained at temperatures up to 625 K for the gas-phase complex formed over POCl3-FeCl3 molten mixtures under static equilibrium conditions. Raman spectra were also measured for molten POCl3-FeCl3 salt mixtures. A comparison of the spectral features of the POCl3-FeCl3 vapours with those of the POCl3-FeCl3 molten mixtures at 525 K indicates that the gas-phase complex has a 1:1 stoichiometry (POCl3 . FeCl3) with characteristic vibrational bands at 95, 362, 530, 1218 and 1268 cm(-1). The data indicate a C-3v symmetry for the POCl3 . FeCl3 complex. The energies of the M<--t charge-transfer transitions in the electronic absorption spectra of the POCl3 . FeCl3 gas-phase complex suggest, in agreement with the Raman data, that complexing occurs through oxygen bridging. The 1:1 POCl3 . FeCl3 molecular liquid complex is the predominant species in equilibrium with POCl3 and iron chloride at temperatures around 500 K. At temperatures below 450 K and in POCl3-rich mixtures the '3:2' ionic liquid compound [Fe(POCl3)(6)][FeCl4](3) was formed at the expense of POCl3 . FeCl3 (I). Two solids were identified at room temperature,yellow POCl3 . FeCl3 and red [Fe(POCl3)(6)][FeCl4](3), and their Raman spectra have been recorded.

Abstract: Polarized laser Raman and FTIR spectroscopies, as well as wide angle X-ray diffraction (WAXD), have been employed in order to investigate the distribution of molecular orientation in uniaxially drawn solution-cast films of well-characterized polyesters, bearing hexyl side chains, at different draw ratios. Both the second (áP2(cos õ)ñ) and fourth (áP4(cos õ)ñ, only with Raman) moments of the segment orientation distribution function have been determined. Results reveal physically meaningful trends of both P2 and P4 with draw ratio. A critical comparison among the three techniques confirms the sensitivity of Raman and FTIR to order at molecular level, when detecting the orientation of a particular segment, compared to similar WAXD results that provide information on the larger scale liquid crystalline domain orientation only and thus correspond to higher values of P2. Therefore, the corresponding dependencies of P2 on draw ratio are also different. A simplified approach for the analysis of the Raman spectra, based on the cylindrical symmetry of the Raman tensors at a specific vibrational normal mode, demonstrates the effectiveness and usefulness of this technique for accurately and fully determining the molecular orientation in rodlike polymers.

Abstract: Raman spectroscopy has been used to study the liquid system ScCl-TaCl5-TaOCl3 at temperatures between 500 and 750oC. In the binary CsCl-TaOCl3 the equilibrium TaOCl4(-) + Cl(-) = TaOCl5(2-) is established. As the TaOCl3 concentration increases, formation of oligomeric ions with bridging oxygen bonds also becomes significant. In the central part of the ternary system considerable oligomerisation occurs, and some melts in this region from glasses when cooled rapidly.

Abstract: We have studied the reduction mechanism and electronic conduction during electrodeposition of tantalum in various TaCl5-alkali chloride melts at temperatures up to 1100 K. This has been performed by simultaneous measurements of impedance and Raman spectra together with cyclic voltammograms. A detailed analysis of electrochemical and spectroscopic results yields the following predominant reduction steps during electrodeposition in pure alkali chloride melts: Ta(V) -Ta(IV)-Ta(0). The equilibrium potentials of the corresponding redox reactions are separated by 40 mV which is clearly resolved in impedance measurements. In LiCl/KCl-eutectic melts a three step mechanism is found with Ta(III) being the intermediate species. In evaluating the impedance data we found indications for electronic contributions which are most prominent with added oxide impurities to the molten electrolyte. Direct evidence for an appreciable electronic conductivity has been obtained by electrochemical polarization measurements. These are reported here the first time for fused KCl-TaCl5/Ta at 1050 K, where electronic conductivities up to 0.5 Ohm(-1) cm(-1) have been measured, i.e. of same order of magnitude as ionic conductivities.

Abstract: Raman spectroscopy has been used to study the liquid system CsCl-NbCl~-Nb0Cl3 at temperatures between 340 and 650 "C. Molten NbOCl3 shows Raman bands typical of bridging and terminal oxygen. In the basic regions of the system the ions NbCl6-, NbOCl52-, and NbOCl4- have been identified. In the acidic region, polymeric ions with bridging oxygen probably coexist with ions with terminal oxygen. The structure of NbCl6-, Nb0Cl52-, and NbOCl4- have been verified by and the interpretation of their spectra assisted with ab initio SCF and CASSCF calculations. SCF calculations have also been performed for NbCl5 and NbOCl3, and VOCl3, VOCl4-, and VOCl52- for comparison. In the binary CsCl-NbOCl3, when xCsCl > 0.5, the equilibrium NbOCl4- + Cl- = NbOCl52- is established. This is also verified by quantum chemical calculations.

Abstract: Raman spectra of molten NdCl3-ACl (A=K,Cs) mixtures have been measured at different compositions and at temperatures up to 800oC. Spectral changes on melting the polycrustalline solids Cs2NaNdCl6, Cs3NdCl6, CsNd2Cl7, K3NdCl6, K2NdCl5 and NdCl3 have been also measured and discussed in terms of possible coordination geometries present in the solid and the liquid. The Raman active modes (ν1,ν2,ν5) of the NdCl6(-3) octahedra have been identified in the rich in alkali metal chloride solids and in melt mixtures. Reduced Raman spectra of the liquid mixtures having high NdCl3 mole fractions reveal, in all spectra, two polarized and two depolarized bands, indicating the formation of bridged and distorded NdCl6(-3) species. The spectral features of pure NdCl3 melt are similar to those measured earlier for the YCl3 liquid for which a "network" like liquid structure has been proposed.

Abstract: Raman spectra of the ''molecular'' polycrystalline solids HgCl2 (D2h16), HgBr2 (C2upsilon12) and of the yellow form of HgI2 (C2upsilon12) were measured from LN2 up to premelting temperatures. Polarized Raman spectra of molten HgX2 (X = Cl, Br, I) were measured at temperatures up to 950 K. The pure rotational band contour and the vibrational rotational contour of the HgX2 vapors were also measured. Upon melting the vibrational modes of the high temperature solid appear to be preserved. The spectra of the three liquids are similar and are best correlated to the spectra of the D2h16 (HgCl2) solid and the vibrational modes of the HgX2 molecules. Reduced Raman spectra of the liquids show splitting of the stretching mode to a doublet, nu1 (A1) and nu1 (B2g), which is attributed to strong intermolecular coupling. The nu2 and nu3 internal modes of the solid are also transferred into the melt. The predominant features of the low frequency reduced spectra is a band, nu(R), which is assigned to the rotatory modes of the HgX2 molecules and can be correlated to both the rotational band contour of the vapor and the librational modes of the solid. With increasing temperature the spectra of the liquid show softening of the rotatory modes and a blue shift of the nu1 mode, both implying weakening of the intermolecular coupling. An overall decrease in the Raman.

Abstract: Raman spectra were obtained at temperatures up to 800 K and pressures up to 6 atm. for vapours over POCI3-AICI3 and POCI3-GaCl3 molten mixtures under static equilibrium conditions. Spectra are also measured for molten POCl3-AlCl3 and POCI3- GaCl3 salt mixtures. A comparison of the spectral features in the PO&-MC13 (M = Al, Ga) vapours with the spectra of the 1: 1 and 1 : 2 POCl3-MCl3 molten mixtures indicates that the vapour complexes have a 1: 1 stoichiometr~ and that complexing occurs through oxygen bridging. Gaseous POCl, l AlC13 remains stable with no sign of decomposition at temperatures up to 825 K, while the POC13 * Gael, vapour complex vaporizes dissociatively. The spectra are interpreted in terms of a C, symmetry for POC13 * AlC13 with a bent P-O-Al bridge (nine polarized and eight depolarized bands assigned) and C, s~metry for POCI, * GaCl,, with a strai~t P-0-Ga bridge (five polarized and six depolarized bands assigned). In the spectra of POCl,--MCl:, (M = Al, Ga) melts several bands are interpreted to account for POC13(AlC13)2(1) (four polarized and six depolarized bands assigned) and POCl,(GaCl,),(l) (two polarized and three depolarized bands assigned) species. Accurate relative Raman intensity measurements are used for determining the the~~~~c functions of the reactions: (a) ~l~(g)~~Ga~Cl~(g) =POC13 (GaCl&(g), in the temperature range 600-800 K and pressures up to 6 atm. ; it is shown that the predominant vapour complex formed has n = 0.5 (POC& - GaC13) and the the~~yn~c functions according to this reaction (n = 0.5) are determined from the Raman experiments as AH� = -37kO.8 W mol-� and A,!?� = -44kl.l ,I mol-� K-i. (b) Ga,Cl,(g) = 2GaCl,(g) in the temperature range 400-800 K and pressures up to 2.5 atm., where the thermodynamic functions are determined as �Ho = 83 + 1.3 k.I mol- l and �Sο = 131*2.2 J mol-� K-1.

Abstract: Raman spectra were obtained at temperatures 375-650 K and pressures up to 4 atm from GaCl,-NbCl, and GaCl,-TaCl, binary mixtures in the liquid and vapour state. The data indicate formation of NbGaCl, and TaGaCl, liquid and vapour dinuclear addition complexes. The spectra were interpreted in terms of a Czu configuration for the MGaCl, (M = Nb, Ta) molecules consisting of a MC16 octahedron sharing an edge with a GaCl, tetrahedron. A comparison of the spectral features of 1: 1 GaCl,-NbCl, and GaCl,- TaCl, molten mixtures with the spectra of the corresponding polycrystalline samples indicates that the proposed identity for the complexes is maintained in all three phases. The NbGaCl, and TaGaCl, complexes exist in the liquid state in a wide temperature range beyond their melting points (125 and 15O�C, respectively) and are shown to undergo dissociation to their components [Nb2C11 ,(l)/NbCl,(l), Ga,Cl,(l) and Ta,Cl, ,,(l)/TaCl,(l)] with increasing temperature. Both complex molecules are identified in the gaseous state in low percentages among the vapours of their components and are almost totally decomposed at temperatures higher than cu 325°C. The enthalpy of the reaction TaCl,(g)+ 1/2Ga,Cl,(g) =TaGaCl,(g) was determined from accurate relative Raman intensity measurements as AH0 = -38+2 kJmol-1.

Abstract: Raman spectra of molten HgX2-Hg (X = Cl, Br, I) systems have been obtained at compositions up to 30 mol % in Hg from 550 to 818 K. The dissolution of mercury in mercury halides gives rise to resonance-enhanced Raman bands which were interpreted to account for Hg2X2 type molecular species formed in all mercury compositions and Hg3X2 type molecules formed at high mercury mole fractions. Spectra were also obtained from HgX2-HgX'2-Hg (X = F, Cl, Br, I) mixtures and were attributed to mixed mercury(I) (sub)halide molecules Hg2XX' formed in the melt. The Hg2X2 and Hg2XX' molecules possess a linear symmetry, and the Hg-Hg stretching frequencies for all 10 molecules were found to be between approximately 180 cm-1 (Hg2F2) and approximately 100 cm-1 (Hg2I2). A linear Hg3 chain is formed in thc Hg3X2 molecules bound to two terminal halides. The formation of Hg3 chains was further confirmed by the Raman spectra of Hg3(AlCl4)2 melts. It is suggested that in the melt mixtures intermolecular interactions between HgX2 and Hg2X2 molecules lead to an alteration of oxidation states which account for a "hopping" like conduction.

Abstract: Modulation and photon counting Raman spectroelectrochemical methods have been applied for studying amorphous carbon electrode surfaces during the electrolysis of HgCl2 in LiCl-KCl eutectic at 370-degrees-C. A new Raman band measured at 152 cm-1 was attributed to subvalent Hg2Cl2 species. The Raman signal arises from the melt solvent having appreciable Hg2Cl2 concentrations in the vicinity of the cathode.