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The influence of colloidal Ti[O.sub.2] nanoparticle contents on the optical properties of poly (9,9'-di-n- octylfluorenyl-2,7-diyl) conjugated polymer (PFO) has been investigated. The solution blending method was used to prepare homogenous PFO/Ti[O.sub.2] nanocomposite. The nanocomposite films were prepared on glass substrates using the spin-coating technique. The films were divided into two groups, the first was left to dry at room temperature while the second was heat-treated at 120°C for 1 h. Absorption and emission spectra showed that the PFO existed in α- and β-phases morphology having monomeric, excimeric, and double excimeric states. In addition, both spectra revealed that Ti[O.sub.2] contents and heat treatment temperature extended the conjugation length of PFO. Finally, emission spectra for both cases exhibited decreasing in the line width of zero- phonon emission spectra and increasing in the vibronic splitting energy, upon increment of the Ti[O.sub.2], led to a significant increase in π-electron delocalization and lower degree in chain disorder. PACS No.: 78.66. Nous etudions l'influence du contenu colloidal de nanoparticules de Ti[O.sub.2] sur les proprietes optiques du polymere conjugue poly(9,9-di-n-octyl fluorenyl-2 7-diyl) (PFO). Nous utilisons le melange de solutions pour preparer du PFO/Ti[O.sub.2] composite homogene. Les films de nano-composites sont prepares sur des substrats de verre par enduction centrifuge. Les films sont divises en deux groupes, le premier est laisse a secher a la temperature de la piece, alors que le second est traite a 120°C pendant une heure. Les spectres d'emission et d'absorption montrent que le PFO existe dans une morphologie de phase α et de phase β, ayant des etats de type monomere, excimere et double excimere. De plus, les spectres dans les deux cas revelent que le contenu en Ti[O.sub.2] et le traitement en temperature etendent la longueur de conjugaison du PFO. Finalement, les spectres d'emission dans les deux cas, montrent une diminution de la largeur de raie des spectres d'emission sans phonon et une augmentation de l'energie de separation vibronique, sous augmentation de Ti[O.sub.2], menant a une augmentation significative de la delocalisation de l'electron π et a un plus bas degre du desordre de chaine. [Traduit par la Redaction], 1. Introduction Conventionally, polymeric materials are filled with synthetic or natural inorganic compounds to improve their optoelectronic properties. Therefore the final optoelectronic properties of the nanocomposites depend on the properties [...]

We demonstrate good optical quality Ti[O.sub.2] thin films grown by atomic layer deposition at 120 [degrees]C. The optical properties were studied using spectroscopic ellipsometry and prism coupling methods. The refractive index was 2.27, and the slab waveguide propagation loss was less than 1 dB/cm at 1.53 um. A high quality resonant waveguide grating was fabricated using a thin Ti[O.sub.2] layer on top of a Si[O.sub.2] grating. OCIS codes: 130.3130, 310.2785, 050.1950.

Titanium oxide (Ti[O.sub.2]) thin films were prepared by different deposition methods. The methods were E-gun evaporation with ion-assisted deposition (IAD), radio-frequency (RF) ion-beam sputtering, and direct current (DC) magnetron sputtering. Residual stress was released after annealing the films deposited by RF ion-beam or DC magnetron sputtering but not evaporation, and the extinction coefficient varied significantly. The surface roughness of the evaporated films exceeded that of both sputtered films. At the annealing temperature of 300 [degrees]C, anatase crystallization occurred in evaporated film but not in the RF ion-beam or DC magnetron-sputtered films. Ti[O.sub.2] films deposited by sputtering were generally more stable during annealing than those deposited by evaporation. OCIS codes: 310.0310, 310.1860, 310.6860, 310.6870.

Radio frequency (rf) sputtering is applied to deposit Nb:Ti[O.sub.2] and Ta:Ti[O.sub.2] films onto (100) SrTi[O.sub.3] substrates at temperatures [T.sub.S] ranging from room temperature to 400 degree Celsius. The results have demonstrated a strong correlation between the electrical conductivity and the intensity of the anatase (004) x-ray diffraction peak.

Titanium oxide thin film properties are investigated as a function of working pressure with emphasis on optical properties. It is demonstrated that the film transmittance increases with the increase of working pressure while the refractive index and extinction coefficient both decrease.

Nitrogen-substituted Ti[O.sub.2] (N-Ti[O.sub.2]) thin film photocatalysts are prepared by the radio frequency magnetron sputtering (RF-MS) deposition method by using a [N.sub.2]/Ar mixture sputtering gas and the effect of the concentration of substituted nitrogen on the characteristics of the N-Ti[O.sub.2] thin films is investigated. The results have confirmed that these thin films remain thermodynamically and mechanically stable even under heat treatment at 673 K. The high substitution of O atoms of Ti[O.sub.2] with the N atoms plays a main role in the band gap narrowing of the thin films.

Ti[O.sub.2]--[Ta.sub.2][O.sub.5] composite films were prepared by a radio frequency ion-beam sputtering deposition process, and the refractive indices and extinction coefficients of the composite films were found to be between those of the Ti[O.sub.2] and [Ta.sub.2][O.sub.5] films. The structure of the as-deposited films was amorphous, and the surface roughness was approximately 0.1 nm. The residual stress of the composite films was less than that of pure Ti[O.sub.2] film. The structure of the composite films after annealing was amorphous, with low surface roughness and slightly increased residual stress. The film containing 6.3% Ti[O.sub.2] displayed better properties than either the pure [TA.sub.2][O.sub.5] or the pure [TA.sub.2][O.sub.5] film. OCIS codes: 310.1620, 310.1860, 310.3840, 310.6860, 310.6870.

Nanocomposite thin films formed by gold nanoparticles embedded in a titanium dioxide matrix are synthesized by pulsed laser deposition. The results proved the possibility of tuning the optical properties of gold-titanium dioxide nanocomposites with the choice of laser irradiation parameters.

Transient photovoltage and photocurrent measurements are employed to determine the recombination and transport kinetics in operating dye-sensitized photovoltaic cells as a function of potential and temperature. The results are consistent with the presence of a distribution of traps below the TiO2 conduction band, the detrapping from which limits both the transport and the recombination of electrons.

Titanium oxide films were prepared by ion-beam-assisted deposition on glass substrates at various substrate temperatures. The effect of the temperature of thermal annealing from 100 [degrees]C to 300 [degrees]C on the optical properties and residual stress was investigated. The influence on the stoichiometry and residual stress of titanium oxides deposited at different substrate temperature was discussed. The residual-stress was minimum and the extinction coefficient was maximum at an annealing temperature of 200 [degrees]C with a substrate temperature of 150 [degrees]C. However, when the substrate temperature was increased to 200 [degrees]C and 250 [degrees]C, the residual stress was minimum and the extinction coefficient was maximum at an annealing temperature of 250 [degrees]C. The spectra of x-ray photoelectron spectroscopy reveal that the films lost oxygen and slowly generated lower suboxides at the annealing temperature at which the residual stress was minimum and the extinction coefficient was maximum. As the annealing temperature increased above the temperature at minimum stress, the lower suboxides began to capture oxygen and form stable oxides. [Ti.sup.O.sub.2] films deposited at substrate temperatures of 200 [degrees]C and 250 [degrees]C were more stable than films deposited at 150 [degrees]C. OCIS codes: 310.3840, 310.6860, 310.6870.

Photoinduced hydrophilic conversion properties of titania nanosheets were investigated. The hydrophilic conversion rate (k) for the monolayer film of titania nanosheets was proportional to the intensity (I) of irradiated light, suggesting that the hydrophilic conversion of titania nanosheet surface proceeded under light-limited conditions even with a high concentration of photoexcited carriers.

The optical and microstructural properties of filters composed of Ti[O.sub.2] and Si[O.sub.2] multilayers deposited by different ion-assisted-deposition (IAD) parameters were investigated. The proper IAD coating conditions for mass-produced, environmentally stable, low-scattering, and low-absorption Ti[O.sub.2]/Si[O.sub.2] multilayers were obtained after comparison of these filters. OCIS codes: 310.3840, 310.6860, 310.6870.

Effects of thermal annealing at 400 [degrees]C on the optical, structural, and chemical properties of Ti[O.sub.2] single-layer, Mg[F.sub.2] single-layer, and Ti[O.sub.2]/Mg[F.sub.2] narrow-bandpass filters deposited by conventional electron-beam evaporation (CE) and plasma ion-assisted deposition (PIAD) were investigated. In the case of Ti[O.sub.2] films, the results show that the annealing of both CE and PIAD Ti[O.sub.2] films increases the refractive index slightly and the extinction coefficient and surface roughness greatly. Annealing decreases the thickness of CE Ti[O.sub.2] films drastically, whereas it does not vary that of PIAD Ti[O.sub.2] films. For PIAD Mg[F.sub.2] films, annealing increases the refractive index and decreases the extinction coefficient drastically. An x-ray photoelectron spectroscopy analysis suggests that an increase in the refractive index and a decrease in the extinction coefficient for PIAD Mg[F.sub.2] films after annealing may be related to the enhanced concentration of MgO in the annealed PIAD Mg[F.sub.2] films and the changes in the chemical bonding states of Mg 2p, F 1s, and O 1s. It is found that (Ti[O.sub.2]/Mg[F.sub.2]) multilayer filters, consisting of PIAD Ti[O.sub.2] and CE Mg[F.sub.2] films, are as deposited without microcracks and are also thermally stable after annealing. OCIS codes: 310.0310, 310.6860, 310.6870.

The optogeometric properties of various sensitive thin films involved in gas sensing applications are investigated by using the m-line technique and atomic force microscopy. Variations of these optical properties are studied under butane and ozone exposure. OCIS codes: 310.2790, 310.6860.

A magnetic field of H=10T was applied perpendicularly or parallel to the surface of the 30BaO.15TiO(sub 2).55GeO(sub 2) (BTG) glass during its crystallization, and the effect of the magnetic field on the crystal orientation and second order optical nonlinearity of the Ba(sub 2)TiGeO(sub 8)crystals formed at the glass surface was examined. The results show that the application of high magnetic fields during crystallization controls the orientation of the crystals and optical properties of BTG crystallized glasses.

A nanostructural anatase TiO(sub 2) and Niobium(Nb)-doped TiO(sub 2) films made by sol-gel methods are examined to study the adsorption and solar light decomposition of acetone. The results show different degradation rate of key surface intermediates on pure and doped TiO (sub 2), though the lower oxidation rate for the Nb-doped film cannot be satisfactorily explained.

Ar/O(sub 2) thermal plasma oxidizing mists of liquid precursors containing titanium tetra-n-butoxide and europium(III) nitrate are used for the synthesis of Eu(super 3+)-doped TiO(sub 2) luminescent nanocrystals. The nanopowders emit bright red light on excitation with UV light, confirming the occurrence of nonradioactive energy transfer from the host lattice to Eu ions.

The photoelectrochemical behavior of degenerate Nb-doped TiO(sub 2) electrodes prepared by pulsed laser deposition on LaAlO(sub 3)(LAO) and SrTiO(sub 3)(STO) was examined to find that increase in the concentration causes a significant decay of titanic photoactivity. The reason for such behavior may be a Burstein-Moss effect, which leads to a blue shift of the spectral limit of photoactivity.

The optical properties of amorphous TiO2 thin films prepared by the sol-gel process and doped with rhodamine 6G (R6G) are studied as a function of R6G doping concentration. The theoretical result demonstrates good agreement when compared with the experimental data of undoped TiO2 sol-gel films, as well as the undoped TiO2 film prepared by sputtering.

Ab inito nonadiabatic (NA) molecular dynamics was used to investigate the observed 6-fs photoinduced electron transfer (ET) from the alizarin chromophore into the TiO(sub 2) surface. This observation was supported by the high level ab inito analysis of the optical absorption spectrum.

The study of the reaction between photogenerated electrons in a dye-free nanocrystalline titanium dioxide film and an iodine/iodide redox couple is presented using transient absorption spectroscopy. Recombination kinetics is measured by recording the transient optical signal following band gap excitation by an ultra violet laser pulse.

Some general conclusions about the photocatalytic behavior of M(super n+) doped or M2On modified TiO2 photocatalysts were drawn by studying of M(super n+) - TiO2 model systems in the form of thin films. Results indicate that the presence of cation M has a deleterious influence in the photoelectrochemical response of the M(super n+) - TiO2 thin films acting as photoanodes.

A study is conducted to compare the visible light reactivities and properties of two sensitized Pt/TiO(sub 2) photocatalysts (Pt/TiO(sub 2)RuL(sub 3)) on which ruthenium bipyridyl complexes (RuL(sub 3)) are anchored through carboxylic (c-RuL(sub 3))or phosphonic (p-RuL(sub 3)) acid groups. The photoreductive dechlorination of CCl(sub 4) and trichloroacetate (TCA) and the hydrogen production in aqueous suspensions were used as probe reactions for the visible light reactivity.

The preparation of TiO2-SiO2 glasses containing Eu(super 3+) ions by sol-gel method is described. The transfer of energy from the O-Ti to the Eu(super 3+) ions is observed.

The influence of processing parameters, such as autoclaving and firing temperatures, on the optical properties of nanocrystalline anatase TiO2, film and on the process of electron injection from the dye fluorescein 27 to the as-prepared films is studied. Transmission electron microscopy and steady-state and time-resolved femtosecond spectroscopy measurements indicated that the larger TiO2 particle and the better its overall crystallinity, the faster the process of electron injection.

An enhancement of ~1.54 mum in photoluminescence (PL) properties due to Yr(super 3+) codoping effects was obtained from Er(super 3+) -Y(super 3+) codoped TiO(sub 2) films annealed at 700 degrees C with molar ratio of Er(super 3+):Y(super 3+):Ti(super 4+)=5:30(~50):100. The enhanced PL intensity can be attributed to contributions by the increased dispersion and distorted local structure of Er(super 3+) ions in Er(super 3+) -Y(super 3+) codoped TiO(sub 2) films.

A high surface area pn-heterojunction between TiO2 and an organic p-type charge transport material (spiro-OMeTAD) is sensitized to visible light using lead sulfide (PbS) quantum dots. It revealed that quantum-dot sensitized solar-state solar cells based on spiro-OMeTAD is shown to be interesting alternative to the dye sensitized systems.

The photoluminescence properties of nanocrystalline titanium dioxide films consisting of predominantly anatase nanoparticles are analyzed. Microscopic models are presented that have described the effects of temperature and ambient conditions on photoluminescence of nanocrystalline titanium dioxide films.

Several structural, chemical and optical characterization analyses are conducted to determine the photovoltaic efficiencies exhibited by the different Ti[O.sub.2] quantum dot sensitized solar cells. Various approaches that can be adopted for enhancing the performance of these cells are also analyzed.

A combination of the x-ray diffraction, x-ray reflectance and optical spectroscopy techniques is employed to explain the mechanisms involved in the formation of the different noble metal nanoparticles in reactively sputtered Ti[O.sub.2] films. Cu and Ag are shown to be the two metals that don' t lead to the formation of any nanoparticle.

Several studies are conducted to study the enhancement observed in the light output of the GaN-based flip-chip light-emitting diodes, which are made from the Si[O.sub.2]/Ti[O.sub.2] distributed Bragg reflector coated on mesa sidewall. Lamp packaging is shown to lead to a significant increase in the output power of these diodes.

A combination of Raman spectra and other techniques is employed to explain the synthesis, characterization and the emission properties of the [Y.sub.2-x][Ln.sub.x][Ti.sub.2][O.sub.7] (Ln = Eu and Gd, x = 0.0,0.05) compounds. Particle size and short range order are found to be the main factors leading to the changes observed in the emission intensity of [Eu.sup.3+].

Several studies are conducted to explain the different effects of annealing on the polymer alignment and performance of the different poly(3-hexylthiophene)/Ti[O.sub.2] hybrid solar cells. The photon-mediated electronic transition is shown to be the main factor leading to high efficiency in these cells.

The article presents a new approach, which can be employed for the polymer-assisted conformal coating of the metal-oxide Ti[O.sub.2] thin films. The films thus produced are shown to exhibit extremely high refractive indices and thicknesses.

Ti[O.sub.2] coated glass surfaces and Ti[O.sub.2] films with nitrate anions, which are either premixed with Ti[O.sub.2] as KN[O.sub.3] or deposited from gaseous N[O.sub.x], are irradiated with broad-band light. Surface charge transfer reactions have oxidized nitrate anions into nitrate radicals and their photochemistry has led to [O.sub.3] formation, which has increased the oxidizing power of these surfaces.

Pulsed laser deposition method is used for preparing nitrogen doped titanium dioxide thin films with improved visible light sensitivity. The photoactivity is N concentration dependent and hydrogen evolution is observed under visible light irradiation without the presence of any organic electron donor.

Strapped porphyrins, designed to bind planar to semiconductor, are prepared as model dyes to analyze the sensitization processes on metal oxide semiconductor nanoparticles surfaces. The studies have shown that on Ti[O.sub.2], the fluorescence emission is fully quenched, while the emission on insulating Zr[O.sub.2] is similar to the solution spectra.

Several studies are conducted to explain the synthesis, properties and the various steady-state transport characteristics of the photoconductors that are based on the dye-sensitized solar cells. The presence of the imbalanced energy band is shown to be the main factor determining the transport behavior of the systems.

Possible ways to design both injection and recombination in quantum dots (QDs) sensitized solar cells (QDSCs) via the appropriate use of molecular dipoles and conformal coatings are discussed. The most favorable sequence of the surface treatment to remarkably increase the photovoltaic performance and the energy conversion efficiency of the devices are also discussed.

The diffuse reflectance transient absorption spectroscopy to dye-sensitized solar cells under operational conditions was applied to directly correlate interfacial electron injection kinetics from a Ru complex sensitizer to a Ti[O.sub.2] nanocrystalline electrode with the incident photon to current efficiency values. The ionic liquid electrolyte was found to reduce the initial electron injection efficiency by suppression of the ~100 ps process.

The work functions of nanocrystalline anatase (Ti[O.sub.2]) thin films and a rutile single crystal are measured by using photoemission spectroscopy (PES). The studies have shown that regular x-ray photoemission spectroscopy (XPS) measurements have reduced the work function after exposure time ranging from seconds to minutes, which are similar in magnitude to artifacts observed on indium tin oxide (ITO) substrates.