Showing papers on "Fourier transform infrared spectroscopy published in 2003"
TL;DR: In this article, a liquid-phase deposition (LPD) method was used on fused quartz by the liquid phase deposition method from a (NH4)2TiF6 aqueous solution upon addition of boric acid (H3BO3) and calcined at various temperatures.
Abstract: TiO2 thin films were prepared on fused quartz by the liquid-phase deposition (LPD) method from a (NH4)2TiF6 aqueous solution upon addition of boric acid (H3BO3) and calcined at various temperatures. The as-prepared films were characterized with thermogravimetry (TG), Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), UV−Visible spectrophotometry (UV−Vis), scanning electron microscopy (SEM), photoluminescence spectra (PL), and X-ray photoelectron spectroscopy (XPS), respectively. The photocatalytic activity of the samples was evaluated by photocatalytic decolorization of methyl orange aqueous solution. It was found that the as-prepared TiO2 thin films contained not only Ti and O elements, but also a small amount of F, N, and Si elements. The F and N came from the precursor solution, and the amount of F decreased with increasing calcination temperature. Two sources of Si were identified. One was from the SiF62- ions, which were formed by a reaction between the treatment solution and quartz ...
1,111 citations
TL;DR: Titanate nanotubes with monodisperse pore-size distribution were synthesized under hydrothermal conditions and the optimized synthesis (100-180°C, longer than 48 hours) was systematically studied in this paper.
Abstract: Titanate nanotubes were synthesized under hydrothermal conditions. The optimized synthesis (100–180 °C, longer than 48 h), thermal and hydrothermal stability, ion exchangeability and consequent magnetic and optical properties of the titanate nanotubes were systematically studied in this paper. First, nanotubes with monodisperse pore-size distribution were prepared. The formation mechanism of the titanate nanotubes was also studied. Second, the thermal and hydrothermal stability were characterized with Xray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR), and Raman spectroscopy. Results showed that sodium ions played a significant role in the stability of the frameworks. Third, the selective ion exchangeability was demonstrated with a series of ions. The ion substitution also enlarged the BET surface area of the titanate nanotubes to 240 m2 g−1. Combination of these two features implied that these nanotubes might be functionalized by substitution of different transitional-metal ions and consequently used for selective catalysis. Magnetism, photoluminescence, and UV/Vis spectra of the substituted titanate nanotubes revealed that the magnetic and optical properties of the nanotubes were modifiable.
892 citations
TL;DR: In this article, the intercalation of the cationic biopolymer chitosan in Na+−montmorillonite, providing compact and robust three-dimensional nanocomposites with interesting functional properties.
Abstract: The objective of this work is the intercalation of the cationic biopolymer chitosan in Na+−montmorillonite, providing compact and robust three-dimensional nanocomposites with interesting functional properties. CHN chemical analysis, X-ray diffraction, Fourier transform infrared spectroscopy, scanning transmission electron microscopy, energy-dispersion X-ray analysis, and thermal analysis have been employed in the characterization of the nanocomposites, confirming the adsorption in mono- or bilayers of chitosan chains depending on the relative amount of chitosan with respect to the cationic exchange capacity of the clay. The first chitosan layer is adsorbed through a cationic exchange procedure, while the second layer is adsorbed in the acetate salt form. Because the deintercalation of the biopolymer is very difficult, the −NH3+Ac- species belonging to the chitosan second layer act as anionic exchange sites and, in this way, such nanocomposites become suitable systems for the detection of anions. These mat...
609 citations
TL;DR: In this paper, the authors have shown that PECVD of tetramethylcyclotetrasiloxane (TMCTS) produces a highly crosslinked networked SiCOH film.
Abstract: Carbon doped oxide dielectrics comprised of Si, C, O, and H (SiCOH) have been prepared by plasma enhanced chemical vapor deposition (PECVD) from mixtures of tetramethylcyclotetrasiloxane (TMCTS) and an organic precursor. The films have been analyzed by determining their elemental composition and by Fourier transform infrared spectroscopy with deconvolution of the absorption peaks. The analysis has shown that PECVD of TMCTS produces a highly crosslinked networked SiCOH film. Dissociation of TMCTS appears to dominate the deposition chemistry as evidenced by the multitude of bonding environments and formation of linear chains and branches. Extensive crosslinking of TMCTS rings occurs through Si–Si, Si–CH2–Si, Si–O–Si, and Si–CH2–O–Si moieties. The films deposited from mixtures of TMCTS and organic precursor incorporate hydrocarbon fragments into the films. This incorporation occurs most probably through the reaction of the organic precursor and the Si–H bonds of TMCTS. Annealing the SiCOH films deposited fro...
600 citations
TL;DR: It is concluded that the Terahertz pulse spectroscopy method has a wide range of applications in pharmaceutical science including formulation, high throughput screening, and inspection in storage.
378 citations
TL;DR: In this article, a real-time analytical procedure is developed to study geopolymerization of amorphous aluminosilicates in real time using Fourier transform infrared (FTIR) spectroscopy.
Abstract: Geopolymerization is a general term to describe all the chemical processes that are involved in reacting aluminosilicates with aqueous alkaline solutions to produce a new class of inorganic binders called geopolymers. In the present work, a novel analytical procedure is developed to study geopolymerization of amorphous aluminosilicates in real time. This procedure involves first conducting a series of well-designed leaching experiments, within which an aluminosilicate is alkali-activated with aqueous alkaline solutions of varying alkalinities and soluble silicate dosages. The leached solutions are diluted and analyzed using inductively coupled plasma equipped with optical emission spectroscopy (ICP−OES), and the activated solid particles are separated, washed, desiccated, and analyzed by Fourier transform infrared (FTIR) spectroscopy. By comparing the results obtained from the ICP−OES and the FTIR analyses, a linear calibration curve can be constructed to correlate the extent of the alkali-activation of t...
375 citations
TL;DR: In this article, a simple sol-gel method was used to synthesize nanometer-scale SnO 2 particles, which were characterized by X-ray diffraction, Fourier transform infrared (FTIR), UV-Vis absorption and photoluminescence spectroscopy.
366 citations
TL;DR: The effect of oxidation on modification of single wall carbon nanotubes (SWCNTs) through successive purification steps has been studied in this paper, where the existence of functional groups in the raw SWCNT material and their modification and almost complete removal after the final annealing step was studied.
343 citations
TL;DR: The feasibility of heteropolyacid (HPA)/sulfonated poly(arylene ether sulfone) composite membranes for use in proton exchange membrane (PEM) fuel cells was investigated in this article.
342 citations
TL;DR: In this paper, the surface and pore structures of porous polyethersulfone (PES) membranes were viewed using scanning electron microscopy (SEM), revealing no surface damage and only a slight alteration in pore structure.
Abstract: Hydrophilic modification of porous polyethersulfone (PES) membranes was achieved by Ar-plasma treatment followed by graft copolymerization with acrylamide (AAm) in the vapor phase. Both surfaces of the modified membranes were found to be highly hydrophilic, the permanency of which depends on the grafting yield. The graft reaction was confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The grafting rate was dependent on plasma exposure time. The surface and pore structures of PES membranes were viewed using scanning electron microscopy (SEM), revealing no surface damage and only a slight alteration in pore structure. As a result of the incorporation of polar functionalities, the glass transition temperature (Tg) of both the Ar-plasma treated and AAm grafted membranes increased. A moderate change in the tensile strength of the modified membranes was also observed. Most importantly, the AAm grafting made the membrane surface less susceptible to adsorption o...
319 citations
TL;DR: In this paper, the chemical and mechanical characteristics of composites made up of HDPE (high-density polyethylene) and lignocellulosic fibers (in the presence or absence of a coupling agent) were analyzed by means of Fourier Transform Infrared Spectrophotometry (FTIR) and Scanning Electron Microscopy (SEM).
TL;DR: The structure of 1% Pt/CeO2 catalyst has been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), Xray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscope as discussed by the authors.
Abstract: A 1% Pt/CeO2 catalyst prepared by the solution combustion method shows a higher catalytic activity for CO oxidation by O2 compared to Pt metal particles. At least six hydrogen atoms are taken up per Pt at −25 °C. The structure of 1% Pt/CeO2 catalyst has been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. Rietveld refinement shows that Pt ions are incorporated into the CeO2 matrix in the form of Ce1-xPtxO2-δ solid solution. A decrease in oxygen content in 1% Pt/CeO2 is seen in relation to pure CeO2. TEM studies show that Pt is dispersed as atoms or ions and only a small amount as Pt metal particles. The Pt(4f) core level region in XPS shows that Pt is present mostly in the Pt2+ ionic state on CeO2 surface. FTIR of 1% Pt/CeO2 shows a strongly adsorbed CO peak at 2082 cm-1 corresponding to oxidized Pt. These structural studies show that Pt ions in the catalyst are substituted for Ce4+...
TL;DR: In this article, a single step combustion process has been used for the synthesis of CuFe2O4 powder from cupric nitrate, ferric nitrates and urea, and detailed physical, electrical and structural characterization of the materials have been carried out for the specimens obtained on sintering at different temperatures up to 1000°C.
TL;DR: In this paper, a solution intercalation of polyethylene-grafted-maleic anhydride (PE-g-MA) into the galleries of organo-modified MgAl layered double hydroxide (OMgAl-LDH) under reflux in xylene was carried out by X-ray diffraction, Fourier transfer infrared (FTIR) spectroscopy, transmission electron microscopy, selected area electron diffraction (SAED), and differential thermal analysis.
Abstract: Exfoliated nanocomposites (PE-g-MA/MgAl-LDH) were synthesized by solution intercalation of polyethylene-grafted-maleic anhydride (PE-g-MA) into the galleries of organo-modified MgAl layered double hydroxide (OMgAl-LDH) under reflux in xylene. Their structural elucidation and thermal characterization were carried out by X-ray diffraction (XRD), Fourier transfer infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The molecular dispersion of OMgAl-LDH layers within the PE-g-MA matrix has been verified by the disappearance of d001 XRD diffraction peak of OMgAl-LDH and the observation of TEM image. The OMgAl-LDH layers of about 70-nm length or width show a disordered phase in PE-g-MA matrix. The SAED pattern demonstrates that the MgAl hydroxide sheets of about 0.48-nm thickness have a hexagonal crystal structure with a = 0.305 nm. TGA profiles of the PE-g-MA/MgAl-LDH nanocompo...
TL;DR: In this article, homopolymer films of Gellan and polyvinyl alcohol (PVA) and blended films were prepared by a solution casting method from a polymer solution in water of Gellian and PVA using glycerol as plasticizer, and they were studied for thermal characteristics by differential scanning calorimetry, for intermolecular interactions by Fourier transform infrared spectroscopy and for the mechanical properties of tear strength, tensile strength (TS) and percentage elongation (%E).
TL;DR: Using surface-enhanced Raman scattering (SERS) and Fourier transform infrared (FTIR) spectroscopy, this article showed that composites based on polyaniline (PANI) and single-walled carbon nanotubes (SWNTs) are different when they are prepared by two different methods.
Abstract: Using surface-enhanced Raman scattering (SERS) and Fourier transform infrared (FTIR) spectroscopy, we show that composites based on polyaniline (PANI) and single-walled carbon nanotubes (SWNTs) are different when they are prepared by two different methods: (1) by adding dispersed SWNTs to the polymer solutions and (2) by chemical polymerization of aniline in the presence of SWNTs. The difference originates from the irreversible chemical transformation of SWNTs in the polymerization medium. The synthesis medium used for the preparation of PANI transforms SWNTs into fragments of shorter length like closed-shell fullerenes. This explains the similarity of SERS and FTIR spectra of the composites PANI/SWNTs and PANI/C60 chemically prepared. All compounds exhibit an absorption band at 1144 cm-1 in their FTIR spectra, increasing with the carbon nanoparticules content, as a signature of a charge transfer between the constituents. Besides, the FTIR spectrum of the compounds obtained by adding SWNTs to the polymer...
TL;DR: In this paper, several metal soaps were synthesized and their X-ray diffraction pattern and Fourier transform infrared (FTIR) pattern was analyzed to characterize more fully the metal soap found in paint films or on metal surfaces.
Abstract: To characterize more fully the metal soaps found in paint films or on metal surfaces, several metal soaps were synthesized and their X-ray diffraction pattern and Fourier transform infrared (FTIR) ...
15 Apr 2003
TL;DR: The FTIR and XPS results suggest that the adsorption of copper ions to the HPANF is attributed to the imine groups on the surface of theHPANF.
Abstract: Polyacrylonitrile fiber (PANF) was hydrolyzed in a solution of sodium hydroxide and the hydrolyzed polyacrylonitrile fiber (HPANF) was used as an adsorbent to remove copper ions from aqueous solution. Scanning electron microscopy (SEM) showed that the hydrolysis process made the surface of HPANF rougher than that of PANF. Fourier transform infrared (FTIR) spectroscopy revealed that the HPANF contained conjugated imine (CN) sequences. Batch adsorption results indicated that the HPANF was very effective in adsorbing copper, and the adsorption equilibrium could be reached within 10–20 min. Atomic force microscopy (AFM) showed that some aggregates formed on the surface of the HPANF after copper ion adsorption and the average surface roughness (Ra) value of the HPANF changed from 0.363 to 3.763 nm due to copper adsorption. FTIR analysis indicated that copper adsorption caused a decrease of the light adsorption intensity of the imine (CN) groups at 1573 and 1406 cm−1 wavenumbers, and X-ray photoelectron spectroscopy (XPS) showed that the binding energy (BE) of some of the nitrogen atoms in the HPANF increased to a greater value due to copper adsorption. The FTIR and XPS results suggest that the adsorption of copper ions to the HPANF is attributed to the imine groups on the surface of the HPANF.
TL;DR: In this paper, the authors reported the immobilization of poly(sodium 4-styrenesulfonate), poly((ar-vinylbenzyl) trimethylammonium chloride), poly(N,N-dimethylacrylamide), and poly(3-[2-(N-methylacrylido)-ethyldimethyl ammonio]propane sulfonate-b-N, N-dimethylamide) onto gold films.
Abstract: Reversible addition−fragmentation chain transfer (RAFT) is a versatile, controlled free radical polymerization technique that operates via a degenerative transfer mechanism in which a thiocarbonylthio compound acts as a chain transfer agent. The subsequent reduction of the dithioester end groups to thiols allows the preparation of (co)polymer-modified gold surfaces. Herein we report the immobilization of poly(sodium 4-styrenesulfonate), poly((ar-vinylbenzyl) trimethylammonium chloride), poly(N,N-dimethylacrylamide), and poly(3-[2-(N-methylacrylamido)-ethyldimethyl ammonio]propane sulfonate-b-N,N-dimethylacrylamide) onto gold films. The presence of the immobilized (co)polymers was confirmed by atomic force microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, and surface contact angle measurements. The gold film modified with the block copolymer demonstrated stimuli-responsive behavior as evidenced by its water contact angle being similar to that of poly(N,N-dimethylacrylamide) ...
TL;DR: In this article, a self-assembling process using cetyltrimethylammonium bromide as an organic template and tetraethyl orthosilicate as the silica source has been used to synthesize mesoporous thin films.
Abstract: Silica mesoporous thin films have been synthesized with a self-assembling process using cetyltrimethylammonium bromide as an organic template and tetraethyl orthosilicate as the silica source. Mesoporous films with Pm3n cubic phase have been obtained and the films have been thermally treated in air with a progressive heating schedule from as-deposited up to 1000 °C. The evolution of silica network has been studied with transmission Fourier transformed infrared (FTIR) spectroscopy. The presence of cyclic species in the precursor solution has been shown by 29Si nuclear magnetic resonance (NMR) experiments. FTIR spectra of as-deposited films have shown that some of these cyclic species are retained in the structure after film deposition, but at temperatures larger than 350 °C they have been no longer observed. In the 1000−1300 cm-1 region, several overlapped absorption bands have been detected. In particular, the LO3−TO3 pair, the cyclic species absorption bands and the LO4−TO4 pair have been resolved. These...
TL;DR: The thermal stability of Cr1−xAlxN thin films with 0≤x≤0.63 has been investigated by isochronal (15 min) heating in air at various temperatures up to 1173 K.
Abstract: The thermal stability against oxidation of Cr1−xAlxN films with 0≤x≤0.63 has been investigated by isochronal (15 min) heating in air at various temperatures up to 1173 K. Cr1−xAlxN thin films were deposited by reactive magnetron sputtering from Cr and Al targets in a mixed Ar/N2 atmosphere at a substrate temperature of 573 K. All the films crystallize in the pseudo binary, rocksalt-type cubic structure, showing a (111) preferential orientation. Oxidation proceeds by de-nitridation and the formation of a pseudo binary, mixed, Cr/Al oxide with the corundum structure. The degree of film oxidation was evaluated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Rutherford backscattering spectroscopy (RBS). The substitution of Cr atoms by Al atoms leads to two oxidation behaviors. Cr1−xAlxN films with low Al content (x 0.2) are more resistant to high temperatures compared to pure CrN. Films with the highest Al content (x=0.63) are stable up to 1173 K due to the formation of an amorphous, aluminum-rich oxide which blocks oxygen diffusion and prevents further film oxidation.
TL;DR: Transmission electron microscopy (TEM) in conjunction with the bulk techniques has allowed a more thorough assessment of the apatites, and has enabled the constituents in these closely related apatite powders to be identified.
Abstract: Powders of hydroxyapatite (HA), partially fluoride-substituted hydroxyapatite (fHA), and fluorapatite (FA) were synthesized in house using optimum methods to achieve relatively pure powders. These powders were assessed by the commonly used bulk techniques of X-ray diffraction (XRD), Fourier transform infra-red (FTIR) and FT-Raman spectroscopies, inductively coupled plasma atomic emission spectroscopy (ICP-AES), and F-selective electrode. In addition, the current study has employed transmission electron microscopy (TEM), involving morphological observation, electron diffraction and energy-dispersive X-ray spectrometry (EDX), as an effective analytical technique to evaluate the powders at a microscopic level. The HA and fHA particles were elongated platelets about 20 x 60 nm in size, while FA particles were over twice this size. Calcination of the HA and fHA powders at 1000 degrees C for 1 h resulted in increased grain size and crystallinity. The calcined fHA material appeared to possess a crystal structure intermediate between HA and FA, as evidenced by the (3 0 0) peak shift in XRD, as well as by the position of the hydroxyl bands in the FTIR spectra. This result was consistent with electron diffraction of individual particles. Small levels of impurities in some of the powders were identified by EDX and electron diffraction, and the carbonate content was detected by FTIR. The use of TEM in conjunction with the bulk techniques has allowed a more thorough assessment of the apatites, and has enabled the constituents in these closely related apatite powders to be identified.
TL;DR: While insulin aggregation under ambient pressure is fast and quantitative, pressure as low as 300 bar is sufficient to prevent the aggregation completely, as high-pressure FTIR spectroscopy revealed.
Abstract: Pressure perturbation calorimetry (PPC), differential scanning calorimetry (DSC), and time-resolved Fourier transform infrared spectroscopy (FTIR) have been employed to investigate aggregation of bovine insulin at pH 1.9. The aggregation process exhibits two distinguished phases. In the first phase, an intermediate molten globule-like conformational state is transiently formed, reflected by loose tertiary contacts and a robust H/D-exchange. This is followed by unfolding of the native secondary structure. The unfolding of insulin is fast, endothermic, partly reversible, and accompanied by a volume expansion of approximately 0.2%. The second phase consists of actual aggregation: an exothermic irreversible process revealing typical features of nucleation-controlled kinetics. The volumetric changes associated with the second phase are small. The concentration-dependence of DSC scans does not support a monomer intermediate model. While insulin aggregation under ambient pressure is fast and quantitative, press...
TL;DR: In this paper, a benzene-thermal reaction between C3N3Cl3 and NaNH2 at 180-220 °C for 8-12 h was reported to yield well-crystallized graphitic carbon nitride nanocrystallites.
TL;DR: In this paper, nano-crystalline BaFe 12 O 19 powders have been prepared at a relatively low calcination temperature by a gel combustion technique using citric acid as a fuel/reductant and nitrates as oxidants.
TL;DR: The phase transfer of silver nanoparticles synthesized in an aqueous medium into hexane containing the cationic surfactant octadecylamine (ODA) is demonstrated, rendering the nanoparticles sufficiently hydrophobic and dispersible in the organic phase.
TL;DR: In this paper, the stability of the β form of polyvinylidene fluoride (PVDF)/clay nanocomposites was ascertained from thermal annealing performed at 125 and 185°C.
Abstract: Polymorphism in poly(vinylidene fluoride) (PVDF)/clay nanocomposites was studied. Poly(vinylidene fluoride)/clay nanocomposites were prepared with melt intercalation. The samples were characterized with X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy. The nanocomposite exhibited the β form. Thermal annealing performed at 125 and 185°C showed that the β form of PVDF was stable. The stability of the β form of PVDF was ascertained from these studies. The β form of PVDF in the nanocomposites could be due to crystallization in the constrained phase. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2036–2040, 2003
TL;DR: In this paper, the photocatalytic activity of sol−gel-derived TiO2 thin films by a simple treatment with trifluoroacetic acid (TFA) was investigated.
Abstract: Enhancement of the photocatalytic activity of sol−gel-derived TiO2 thin films by a simple treatment with trifluoroacetic acid (TFA) was investigated. The thin films were characterized with N2 adsorption, Fourier transform infrared spectroscopy, UV−visible spectroscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, X-ray diffraction, atomic force microscopy, and differential thermal analysis/thermogravimetry analysis. The photocatalytic activity of the thin films was evaluated by the photocatalytic decomposition of acetone in air. The results show that TFA is chemisorbed on the surface of the TiO2 films as a trifluoroacetate complex. The photocatalytic activity of modified TiO2 thin films is higher than that of unmodified TiO2 thin films, and the modified film treated at 250 °C shows the highest activity. This is ascribed to the fact that the TFA complex bound on the surface of TiO2 acts as an electron scavenger and, thus, reduces the recombination of photogenerated electrons and holes....
TL;DR: In this article, a multilayer ultrathin film composed of exfoliated nanosheets of manganese oxide and poly(diallyldimethylammonium) (PDDA) ions have been fabricated onto various substrates via electrostatic self-assembly technique.
Abstract: Multilayer ultrathin films composed of exfoliated nanosheets of manganese oxide and poly(diallyldimethylammonium) (PDDA) ions have been fabricated onto various substrates via electrostatic self-assembly technique. Dense monolayer coverage of the substrate surface by the nanosheets was confirmed by atomic force microscopy. UV−vis absorption spectroscopy provided evidence for subsequent growth of multilayer film, exhibiting progressive enhancement of optical absorption due to manganese oxide nanosheets. Evolution of a Bragg peak in the layer-by-layer deposition process also supported the growth of a nanostructured film of PDDA/MnO2 nanosheets with a repeating periodicity of ca. 0.9 nm. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy revealed the inorganic−organic hybrid nature of the obtained multilayer assemblies. Calcination of the films at temperatures above 500 °C removed the polycations, yielding an ultrathin film of manganese oxide Mn2O3. Cyclic voltammogram measurements r...
TL;DR: In this article, a series of WO4 tetrahedron on the surface of trimetallic catalysts was studied and their catalytic performance for the oxidative coupling of methane (OCM) was evaluated in a continuous flow microreactor.