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7. Experimental arrangement for attenuated total reflection spectroscopy: (a) crystal block, (b) internal reflection in the block, (c) penetration of the evanescent wave into the sample pressed against the block.
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Ruthenium(II) complexes containing polypyridyl ligands are intensely investigated as potential photosensitizers in organic solar cells. Of particular interest is their use in dye-sensitized solar cells based on nanocrystalline films of TiO2. Functional groups of the dye allow for efficient anchoring on the semiconductor surface and promote the elec...
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In recognition of the potentials of gold nanoparticles (Au NPs) in enhanced photodynamic therapy (PDT) for cancer, it is desirable to further understand the shape-dependent surface plasmonic resonance (SPR) properties of various gold nanostructures and evaluate their performances in PDT.
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... The dashed vertical gray lines are established experimental modes for the N719 dye and are at the frequencies 1230, 1380, 1450, 1540, 1600, 1720 and 2100 cm -1 , respectively 36 . The two grey spectral insets are experimental ATR-FTIR results from ref. 37, with the topmost one being the spectra for unsolvated N719 powder and the bottom one that for unsolvated N719 powder adsorbed on anatase. These experimental results are intended as a guide only, in that the spectra are slightly different in other studies and the two experimental insets are themselves somewhat different due to adsorption to anatase. ...
... Indeed, where the empirical-potential models do fail in the present N719 scenario -somewhat spectacularly, it must be admitted -is in the spectral region between 1800 and 2000 cm -1 . Both the PBE-Grimme-BOMD 20 and experimental results 37 show little activity in this region, whereas all classical-charge parametrizations show, erroneously and misleadingly, strong modes. This, and the already-mentioned lack of the thiocyano mode is most likely due to the forcefield model of the dye (OPLS, in the present case) being unable to capture properly this dynamical behavior. ...
... The dashed vertical grey lines are established experimental modes for the N719 dye, and are at 1230, 1380, 1450, 1540, 1600, 1720 and 2100 cm −1 . The two grey spectral insets are experimental results from ref. 25, with the topmost one being spectra for the unsolvated N719 powder, and the bottom one being for unsolvated N719 powder on anatase. These experimental results are meant as a guide only, as the spectra are slightly different in other studies and the two experimental insets themselves are quite different due to the inclusion of the anatase and N719 binding thereon. ...
... Vibrational Spectra of (a) BLYP system I, (b) PBE system I, (c) BLYP system II and (d) PBE system II. Within each plot the grey (lower)/(upper) inset corresponds to the experimental ATR-FTIR signal from reference[25] for (dry-N719 adsorbed onto anatase)/(dry-N719 powder). The dashed lines indicate established vibrational modes[26]. . ...
... Vibrational Spectra of (a) BLYP system I, (b) PBE system I, (c) BLYP system II and (d) PBE system II. Within each plot the grey (lower)/(upper) inset corresponds to the experimental ATR-FTIR signal from reference[25] for (dry-N719 adsorbed onto anatase)/(dry-N719 powder). The dashed lines indicate established vibrational modes[26]. ...
The accurate ab-initio modelling of prototypical and well-representative photo-active interfaces for candidate dye-sensitised solar cells is a challenging problem. To this end, using ab-initio molecular-dynamics (AIMD) simulation based on Density Functional Theory (DFT), the effects of explicit solvation by iodide-based, I−[bmim]+ room-temperature ionic liquids (RTILs) have been assessed on modelling a N719-chromophore sensitising dye adsorbed onto an anatase-titania (101) surface. In particular, the vibrational spectra for this model photo-active interface were calculated by means of Fourier transformed mass-weighted velocity autocorrelation functions. These were compared with experiment and against each other to gain an understanding of how using iodine-based RTILs as the electrolytic hole acceptor alters the dynamical properties of the widely-used N719 dye. The effect of Perdew-Burke-Ernzerhof (PBE) and Becke-Lee-Yang-Parr (BLYP) functionals on the vibrational spectra were assessed. PBE generally performed best in producing spectra which matched the typically expected experimental frequency modes.
... The signal at 1028 cm −1 corresponds to the ring stretching band of the bipyridin rings. The signals at 1267 cm −1 , 1477 cm −1 , 1543 cm −1 and 1610 cm −1 refer to (C N) and (C C) vibrations on the bipyridin rings [16,17]. Clearly, the signal intensities are very low in the inner region of the laser-fabricated surface structure where the large pore is located. ...
Photothermal processing of nanoporous gold with a microfocused continuous-wave laser at λ = 532. nm provides a facile means in order engineer the pore and ligament size of nanoporous gold. In this report we take advantage of this approach in order to investigate the size-dependence of enhancement effects in surface-enhanced Raman spectroscopy (SERS). Surface structures with laterally varying pore sizes from 25. nm to ≥200. nm are characterized using scanning electron microscopy and then functionalized with N719, a commercial ruthenium complex, which is widely used in dye-sensitized solar cells. Raman spectroscopy reveals the characteristic spectral features of N719. Peak intensities strongly depend on the pore size. Highest intensities are observed on the native support, i.e. on nanoporous gold with pore sizes around 25. nm. These results demonstrate the particular perspectives of laser-fabricated nanoporous gold structures in fundamental SERS studies. In particular, it is emphasized that laser-engineered porous gold substrates represent a very well defined platform in order to study size-dependent effects with high reproducibility and precision and resolve conflicting results in previous studies.
... De manera que es posible obtener un espectro del coeficiente de absorción, α como función de la energía incidente, utilizando la ley de Lambert-Beer que relaciona linealmente este parámetro con la absorbancia A, descrita por la relación [64] : ...
El trabajo presenta la caracterización morfológica (rugosidad y topografía), estructural (densidad y tamaño promedio de nanocristales dentro de la matriz amorfa) y óptica (brecha óptica prohibida, Eg ) de muestras de películas delgadas de pm-Si:H depositadas por PECVD usando SiH2Cl2 como gas precursor de Si, cada una a distinta dilución de hidrógeno (DH) y a dos presiones distintas de trabajo.
Se realizó un análisis químico a cada muestra (composición atómica por XPS y densidad y tipos de enlaces por FTIR) para discutir e interpretar las diferencias observadas en las caracterizaciones debidas a las distintas condiciones de crecimiento.
Posteriormente las muestras se sometieron a una prolongada exposición de radiación
equivalente a la del sol para de esta forma medir las variaciones en la fotoconductividad. También se realizaron mediciones de conductividad en obscuridad en diferentes tiempos para obtener las diferencias en sus propiedades electrónicas (una estimación del producto movilidad-tiempo de vida y de la longitud de difusión de los portadores minoritarios) y con ello se determinó el grado de pasivación y estabilidad de cada estructura en base a la composición y comportamiento químico.
... This peak is assigned to Ru−O, which might have resulted from the interaction of the N719 dye with oxalate ions present at the OA-TiO 2 surface. 23 Furthermore, the relative amount of bound N719 dye molecules on the TiO 2 surface has been estimated by the relative intensity of the peak at free carboxylic acid (CO, 1723 cm −1 ) and carboxylate groups (COO − , 1373 cm −1 ). 24,25 Because the carbonyl group peak at 1719 cm −1 for the OA-TiO 2 electrode has contributions from the dye as well as oxalic acid, it is difficult to determine quantitatively the amount of N719 dye on the OA-TiO 2 surface. ...
The anchoring mechanism of N719 dye molecules on oxalic acid treated TiO2 (OA-TiO2) electrodes has been investigated using extended X-ray absorption fine structure (EXAFS) measurements, Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy, and X-ray photoelectron spectroscopy (XPS). The FTIR spectroscopy of OA-TiO2 electrodes revealed that the oxalic acid dissociates at the TiO2 surface and binds through bidentate chelating and/or bidentate bridging. Analyses of EXAFS, FTIR, UV–vis, and XPS measurements of N719 dye loaded onto OA-TiO2 revealed that the binding of N719 molecules takes place via interaction between the Ru atom of the dye and O– of bidentate bridged oxalate ions at the TiO2 surface. This mechanism is quite different from the binding of N719 onto untreated TiO2 (WO-TiO2) surface, where −COOH and SCN groups of the dye directly bind to the TiO2 surface. The analyses of UV–vis data show that the amount of N719 dye loading onto OA-TiO2 surface is much higher than that onto the native TiO2 surface. In addition, the incident photon-to-current conversion efficiency (IPCE) measurements show that the presence of oxalate ions between the dye and TiO2 surface favors efficient electron transfer and therefore improvement in device efficiency. The dye-sensitized solar cells fabricated using N719 dye sensitized onto OA-TiO2 showed an efficiency of 4.6%, which is significantly higher than that based on a WO-TiO2 electrode (3.2%).
... Fig. 1 shows FTIR spectra of both samples with peak at 1655 cm −1 characteristics of amide carbonyl stretch vibration attributed to PVP and shifts to 1650 cm −1 due to stretching of (C C) of Bipy. The (C N) appears at 1455 and 1325 cm −1 for Bipy and 1381 and 1327 cm −1 for PVP [15,13]. The peaks in both cases were slightly shifted but due to Bipy transmittance intensity at those regions were greatly reduced. ...
The fine tuning of localized surface plasmon resonance (LSPR) of Ag-NP film containing 2,2-bipyridine (bipy), self-assemble at room temperature when solution cast from dispersions on the glass substrate is described. The suspension of Ag colloid was prepared via polyol reduction stabilization using microwave radiations. SEM, EDS study reveals that NPs are uniform in size and reduced to metallic Ag. The cooperative SPR (approx. at 418 nm) of 2D assembly has been depressed due to 2,2-bipyridine ligand structured around Ag-NPs showing red shift (456 nm). The cooperative resonance can be controlled by varying impingement time of microwave power on film. As the impingement time increased cooperative resonance begins blue shift due to increase in the cooperative interaction between Ag-NPs via decomposition of bipyridine. The cooperative resonance of 2D assembly that is at 418 nm was regained after complete removal of 2,2-bipyridine at higher temperatures thus showing tunable LSPR properties of Ag-Bipy nanostructure. Opposite type of behavior that is strong damping were seen in case of Ag-NPs in solution phase. Temperature dependent viscosity characteristics suggest that Plasmon damping can be attributed to decrease in viscosity of Ag-NP solution.
... Fig. 1 shows FTIR spectra of both samples with peak at 1655 cm −1 characteristics of amide carbonyl stretch vibration attributed to PVP and shifts to 1650 cm −1 due to stretching of (C C) of Bipy. The (C N) appears at 1455 and 1325 cm −1 for Bipy and 1381 and 1327 cm −1 for PVP [15,13]. The peaks in both cases were slightly shifted but due to Bipy transmittance intensity at those regions were greatly reduced. ...
The fine tuning of localized surface plasmon resonance (LSPR) of Ag-NP film containing 2,2′-bipyridine (bipy), self-assemble at room temperature when solution cast from dispersions on the glass substrate is described. The suspension of Ag colloid was prepared via polyol reduction stabilization using microwave radiations. SEM, EDS study reveals that NPs are uniform in size and reduced to metallic Ag. The cooperative SPR (approx. at 418nm) of 2D assembly has been depressed due to 2,2′-bipyridine ligand structured around Ag-NPs showing red shift (456nm). The cooperative resonance can be controlled by varying impingement time of microwave power on film. As the impingement time increased co-operative resonance begins blue shift due to increase in the cooperative interaction between Ag-NPs via decomposition of bipyridine. The co-operative resonance of 2D assembly that is at 418nm was regained after complete removal of 2,2′-bipyridine at higher temperatures thus showing tunable LSPR properties of Ag-Bipy nanostructure. Opposite type of behavior that is strong damping were seen in case of Ag-NPs in solution phase. Temperature dependent viscosity characteristics suggest that Plasmon damping can be attributed to decrease in viscosity of Ag-NP solution.
MoO3/TiO2 composite nanopowders are synthesized using mechanochemical synthesis technique and are characterized by PXRD, SEM with EDS, FT-IR, Raman and TGA/DTA. The average crystalline sizes, lattice strain and phase structures are evaluated from XRD. The vibrational and Raman mode are revealed by FTIR and Raman spectra. The morphological studies were performed by SEM with EDS spectra. The fundamental modes and other functional groups were analyzed by FT-IR. TGA/DTA analysis revealed that the nanopowders are stable up to 780oC with a negligible weight loss. Hence the synthesized oxide nanocomposite may be used as a solid lubricant at elevated temperatures.
