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Showing papers on "Infrared spectroscopy published in 2010"


Journal ArticleDOI
TL;DR: The observation of a giant-infrared-absorption band in reduced graphene oxide is reported, arising from the coupling of electronic states to the asymmetric stretch mode of a yet-unreported structure, consisting of oxygen atoms aggregated at the edges of defects.
Abstract: Infrared absorption of atomic and molecular vibrations in solids can be affected by electronic contributions through non-adiabatic interactions, such as the Fano effect. Typically, the infrared-absorption lineshapes are modified, or infrared-forbidden modes are detectable as a modulation of the electronic absorption. In contrast to such known phenomena, we report here the observation of a giant-infrared-absorption band in reduced graphene oxide, arising from the coupling of electronic states to the asymmetric stretch mode of a yet-unreported structure, consisting of oxygen atoms aggregated at the edges of defects. Free electrons are induced by the displacement of the oxygen atoms, leading to a strong infrared absorption that is in phase with the phonon mode. This new phenomenon is only possible when all other oxygen-containing chemical species, including hydroxyl, carboxyl, epoxide and ketonic functional groups, are removed from the region adjacent to the edges, that is, clean graphene patches are present.

724 citations


Journal ArticleDOI
TL;DR: The high permanent porosity of 1 allows for rapid diffusion of oxygen through the open channels, leading to efficient and reversible quenching of the (3)MLCT phosphorescence, highlighting the opportunity of designing highly porous and luminescent coordination polymers for sensing other important analytes.
Abstract: Phosphorescent cyclometalated iridium tris(2-phenylpyridine) derivatives were designed and incorporated into coordination polymers as tricarboxylate bridging ligands. Three different crystalline coordination polymers were synthesized using a solvothermal technique and were characterized using a variety of methods, including single-crystal X-ray diffraction, PXRD, TGA, IR spectroscopy, gas adsorption measurements, and luminescence measurements. The coordination polymer built from Ir[3-(2-pyridyl)benzoate]3, 1, was found to be highly porous with a nitrogen BET surface area of 764 m2/g, whereas the coordination polymers built from Ir[4-(2-pyridyl)benzoate]3, 2 and 3, were nonporous. The 3MLCT phosphorescence of each of the three coordination polymers was quenched in the presence of O2. However, only 1 showed quick and reversible luminescence quenching by oxygen, whereas 2 and 3 exhibited gradual and irreversible luminescence quenching by oxygen. The high permanent porosity of 1 allows for rapid diffusion of ...

569 citations


Journal ArticleDOI
TL;DR: In this paper, the Fourier transform infrared (FTIR) spectroscopic characterization of natural kaolinite from north-eastern India has been performed at room temperature by using X-ray fluorescence (XRF), electron microprobe (EPMA) analyses and FTIR techniques.
Abstract: This study demonstrates the Fourier transform infrared (FTIR) spectroscopic characterization of natural kaolinite from north-eastern India. The compositional and structural studies were carried out at room temperature by using X-ray fluorescence (XRF), electron microprobe (EPMA) analyses and Fourier transform infrared (FTIR) spectroscopic techniques. The main peaks in the infrared spectra reflected Al-OH, Al-O and Si-O functional groups in the high frequency stretching and low frequency bending modes. Few peaks of infrared spectra inferred to the interference peaks for quartz as associated minerals. The present study demonstrates usefulness of the spectroscopic techniques in determining quality and crystalline nature of kaolinite from the Assam and Meghalaya, northeastern India.

534 citations


Journal ArticleDOI
TL;DR: This critical review describes the reactivity of heterogeneous catalysts from the point of view of four simple, but essential for Chemistry, molecules that are considered as probes or as reactants in combination with "in situ" controlled temperature and pressure Infrared spectroscopy.
Abstract: This critical review describes the reactivity of heterogeneous catalysts from the point of view of four simple, but essential for Chemistry, molecules (namely dihydrogen, carbon monoxide, nitrogen monoxide and ethylene) that are considered as probes or as reactants in combination with “in situ” controlled temperature and pressure Infrared spectroscopy. The fundamental properties of H2, CO, NO and C2H4 are shortly described in order to justify their different behaviour in respect of isolated sites in different environments, extended surfaces, clusters, crystalline or amorphous materials. The description is given by considering some “key studies” and trying to evidence similarities and differences among surfaces and probes (572 references).

386 citations


Journal ArticleDOI
01 Oct 2010-ACS Nano
TL;DR: IR spectroscopy, XPS analysis, and DFT calculations all confirm that the water molecules play a significant role interacting with basal plane etch holes through passivation, via evolution of CO(2) leading to the formation of ketone and ester carbonyl groups.
Abstract: A detailed in situ infrared spectroscopy analysis of single layer and multilayered graphene oxide (GO) thin films reveals that the normalized infrared absorption in the carbonyl region is substantially higher in multilayered GO upon mild annealing. These results highlight the fact that the reduction chemistry of multilayered GO is dramatically different from the single layer GO due to the presence of water molecules confined in the ∼1 nm spacing between sheets. IR spectroscopy, XPS analysis, and DFT calculations all confirm that the water molecules play a significant role interacting with basal plane etch holes through passivation, via evolution of CO2 leading to the formation of ketone and ester carbonyl groups. Displacement of water from intersheet spacing with alcohol significantly changes the chemistry of carbonyl formation with temperature.

356 citations


Journal ArticleDOI
TL;DR: Fourier transform spectroscopy in the mid-infrared (FT-IR) is being recognized as a powerful tool for analyzing chemical composition of food, with special concern to molecular architecture of food proteins.
Abstract: Fourier transform spectroscopy in the mid-infrared (400–5,000 cm−1) (FT-IR) is being recognized as a powerful tool for analyzing chemical composition of food, with special concern to molecular architecture of food proteins. Unlike other spectroscopic techniques, it provides high-quality spectra with very small amount of protein, in various environments irrespective of the molecular mass. The fraction of peptide bonds in α-helical, β-pleated sheet, turns and aperiodic conformations can be accurately estimated by analysis of the amide I band (1,600–1,700 cm−1) in the mid-IR region. In addition, FT-IR measurement of secondary structure highlights the mechanism of protein aggregation and stability, making this technique of strategic importance in the food proteomic field. Examples of applications of FT-IR spectroscopy in the study of structural features of food proteins critical of nutritional and technological performance are discussed.

334 citations


Journal ArticleDOI
19 Jan 2010-Langmuir
TL;DR: This work rationalizes the different reaction paths and optimize the reaction conditions to obtain as pure as possible succinimidyl ester-terminated surfaces and maps the surface composition after activation was constructed by systematically varying the solution composition.
Abstract: Infrared spectroscopy is used to investigate the transformation of carboxyl-terminated alkyl chains immobilized on a surface into succinimidyl ester-terminated chains by reaction with an aqueous solution of N-ethyl-N'-(3-(dimethylamino)propyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The acid chains are covalently grafted at the surface of hydrogenated porous silicon whose large specific surface area allows for assessing the activation yield in a semiquantitative way by infrared (IR) spectroscopy and detecting trace amounts of surface products and/or reaction products of small IR cross section. In this way, we rationalize the different reaction paths and optimize the reaction conditions to obtain as pure as possible succinimidyl ester-terminated surfaces. A diagram mapping the surface composition after activation was constructed by systematically varying the solution composition. Results are accounted for by NHS surface adsorption and a kinetic competition between the various EDC-induced surface reactions.

320 citations


Journal ArticleDOI
TL;DR: In this paper, a combined methodology comprising variable-temperature infrared spectroscopy and ab initio periodic DFT-D calculations using the CRYSTAL code was used to investigate the adsorption of carbon monoxide, dinitrogen, and carbon dioxide on the porous metal-organic framework Mg-MOF-74.
Abstract: Adsorption of carbon monoxide, dinitrogen, and carbon dioxide on the porous metal−organic framework Mg-MOF-74 was investigated by means of a combined methodology comprising variable-temperature infrared spectroscopy and ab initio periodic DFT-D calculations using the CRYSTAL code. Both CO and N2 were found to form nearly linear (Mg2+···CO and Mg2+···NN) adsorption complexes, in contrast with CO2, which forms an angular Mg2+···OCO complex. From IR spectra recorded at a variable-temperature, the standard adsorption enthalpy (ΔH0) was found to be −29, −21, and −47 kJ mol−1 for CO, N2, and CO2, respectively. Calculated values of ΔH0, including an empirical correction for dispersion forces, resulted to be in a reasonably good agreement with those experimentally obtained. Calculations also showed the very significant role played by dispersion forces, which account for about one-half of the adsorption enthalpy for each of the three adsorbates, CO, N2, and CO2. The results are discussed in the broader context of ...

303 citations


Journal ArticleDOI
TL;DR: A series of CdSe quantum dot-sensitized TiO2 heterostructures have been synthesized, characterized, and tested for the photocatalytic reduction of CO2 in the presence of H2O.
Abstract: A series of CdSe quantum dot (QD)-sensitized TiO2 heterostructures have been synthesized, characterized, and tested for the photocatalytic reduction of CO2 in the presence of H2O. Our results show that these heterostructured materials are capable of catalyzing the photoreduction of CO2 using visible light illumination (λ > 420 nm) only. The effect of removing surfactant caps from the CdSe QDs by annealing and using a hydrazine chemical treatment have also been investigated. The photocatalytic reduction process is followed using infrared spectroscopy to probe the gas-phase reactants and gas chromatography to detect the products. Gas chromatographic analysis shows that the primary reaction product is CH4, with CH3OH, H2, and CO observed as secondary products. Typical yields of the gas-phase products after visible light illumination (λ > 420 nm) were 48 ppm g−1 h−1 of CH4, 3.3 ppm g−1 h−1 of CH3OH (vapor), and trace amounts of CO and H2.

303 citations


Journal ArticleDOI
28 Sep 2010-Langmuir
TL;DR: Results show that the assembled RGO possesses good friction reduction and antiwear ability, properties ascribed to its intrinsic structure, that is, the covalent bonding to the substrate and self-lubricating property of RGO.
Abstract: Reduced graphene oxide (RGO) sheets were covalently assembled onto silicon wafers via a multistep route based on the chemical adsorption and thermal reduction of graphene oxide (GO). The formation and microstructure of RGO were analyzed by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, Raman spectroscopy, and water contact angle (WCA) measurements. Characterization by atomic force microscopy (AFM) was performed to evaluate the morphology and microtribological behaviors of the samples. Macrotribological performance was tested on a ball-on-plate tribometer. Results show that the assembled RGO possesses good friction reduction and antiwear ability, properties ascribed to its intrinsic structure, that is, the covalent bonding to the substrate and self-lubricating property of RGO.

296 citations


Journal ArticleDOI
TL;DR: This protocol describes sample preparation, the application of IR spectroscopy tools, and computational analysis for the identification of class clustering as well as class-specific chemical entities in intact cells.
Abstract: Infrared (IR) spectroscopy of intact cells results in a fingerprint of their biochemistry in the form of an IR spectrum; this has given rise to the new field of biospectroscopy. This protocol describes sample preparation (a tissue section or cytology specimen), the application of IR spectroscopy tools, and computational analysis. Experimental considerations include optimization of specimen preparation, objective acquisition of a sufficient number of spectra, linking of the derived spectra with tissue architecture or cell type, and computational analysis. The preparation of multiple specimens (up to 50) takes 8 h; the interrogation of a tissue section can take up to 6 h (∼100 spectra); and cytology analysis (n = 50, 10 spectra per specimen) takes 14 h. IR spectroscopy generates complex data sets and analyses are best when initially based on a multivariate approach (principal component analysis with or without linear discriminant analysis). This results in the identification of class clustering as well as class-specific chemical entities.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated long-term chemical aging of model biogenic secondary organic aerosol (SOA) prepared from the ozonolysis of terpenes using electrospray ionization mass spectrometry (ESI-MS), UV-visible spectroscopy, Fourier transform infrared (FTIR), NMR, and three-dimensional fluorescence.
Abstract: [1] This study investigated long-term chemical aging of model biogenic secondary organic aerosol (SOA) prepared from the ozonolysis of terpenes. Techniques including electrospray ionization mass spectrometry (ESI-MS), UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, NMR, and three-dimensional fluorescence were used to probe the changes in chemical composition of SOA collected by impaction on substrates and also of aqueous extracts of SOA. The addition of ammonium ions or amino acids to limonene SOA reproducibly produced orange-colored species that strongly absorbed visible radiation and fluoresced at UV and visible wavelengths. Simultaneous addition of H2SO4 to the SOA aqueous extracts inhibited this color transformation. These observations suggest the existence of aging processes leading to heavily conjugated molecules containing organic nitrogen. The presence of nitrogen in the chromophores was confirmed by the dependence of the absorption and fluorescence spectra on the amino acids added. In contrast to the strong change in the absorption and fluorescence spectra, there was no significant change in the ESI-MS, FTIR, and NMR spectra, suggesting that the chromophores were minor species in the aged SOA. Aqueous extracts of aged limonene + NH4+ SOA were characterized by an effective base-e absorption coefficient of ∼3 L g−1 cm−1 at 500 nm. Assuming particulate matter concentrations typical of polluted rural air gives an upper limit of 0.2 M m−1 for the aerosol absorption coefficient due to the aged limonene oxidation products. Biogenic SOA can therefore become weakly absorbing if they undergo aging in the presence of NH4+-containing aerosol.

Journal ArticleDOI
TL;DR: This tutorial review describes recent progress in using Attenuated Total Reflection spectroscopy for studying heterogeneous catalysts in water and illustrates that ATR-IR holds great promise in the field of liquid phase heterogeneous catalysis.
Abstract: IR spectroscopy has been an important tool for studying detailed interactions of reactants and reaction-intermediates with catalyst surfaces. Studying reactions in water is, however, far from trivial, due to the excessive absorption of infrared light by water. One way to deal with this is the use of Attenuated Total Reflection spectroscopy (ATR-IR) minimizing the path length of infrared light through the water. Moreover, ATR-IR allows for a direct comparison of reactions in gas and water on the same sample, which bridges the gap between separate catalyst investigations in gas and liquid phase. This tutorial review describes recent progress in using ATR-IR for studying heterogeneous catalysts in water. An overview is given of the important aspects to be taken into account when using ATR-IR to study heterogeneous catalysts in liquid phase, like the procedure to prepare stable catalyst layers on the internal reflection element. As a case study, CO adsorption and oxidation on noble metal catalysts is investigated with ATR-IR in gas and water. The results show a large effect of water and pH on the adsorption and oxidation of CO on Pt/Al(2)O(3) and Pd/Al(2)O(3). From the results it is concluded that water affects the metal particle potential as well as the adsorbed CO molecule directly, resulting in higher oxidation rates in water compared to gas phase. Moreover, also pH influences the metal particle potential with a clear effect on the observed oxidation rates. Finally, the future outlook illustrates that ATR-IR spectroscopy holds great promise in the field of liquid phase heterogeneous catalysis.

Journal ArticleDOI
TL;DR: The solid-state route provides nearly pure Ag(9) clusters, and nanoparticle contamination was insignificant for routine studies, and the cluster showed luminescence with a quantum yield of 8 × 10−3 at 5 °C.
Abstract: A silver cluster having the composition Ag9(H2MSA)7 (H2MSA = mercaptosuccinic acid) was synthesized in macroscopic quantities using a solid-state route. The clusters were purified by PAGE and characterized by UV−vis, FTIR, luminescence, and NMR spectroscopy, TEM, XPS, XRD, TG, SEM/EDAX, elemental analysis, and ESI MS. The solid-state route provides nearly pure Ag9 clusters, and nanoparticle contamination was insignificant for routine studies. Formation of various clusters was observed by modifying the conditions. The effect of ligands on the synthesis was checked. The cluster decomposed slowly in water, and the decomposition followed first-order kinetics. However, it could be stabilized in solvent mixtures and in the solid state. Such materials may be important in cluster research because of their characteristic absorption profiles, which are similar to those of Au25 and Au38. The cluster showed luminescence with a quantum yield of 8 × 10−3 at 5 °C.

Journal ArticleDOI
TL;DR: The main degradation mechanism is suggested to be hydrolysis of the siloxane bonds (Si−O−Si) as opposed to dealumination, which dominates under steaming conditions as discussed by the authors.
Abstract: Zeolites Y and ZSM-5 with varying Si/Al ratios are treated in liquid water at 150 and 200 °C under autogenic pressure to assess their hydrothermal stability. The changes in the structure are characterized by atomic absorption spectroscopy, X-ray diffraction, scanning electron microscopy, argon physisorption, 27Al and 29Si MAS NMR spectroscopy, temperature-programmed desorption of ammonia, and pyridine adsorption followed by IR spectroscopy. During treatment in hot water, zeolite Y with a Si/Al ratio of 14 or higher is transformed into an amorphous material, and the rate of this degradation increases with increasing Si/Al ratio. In contrast, ZSM-5 is not modified under the same conditions. The main degradation mechanism is suggested to be hydrolysis of the siloxane bonds (Si−O−Si) as opposed to dealumination, which dominates under steaming conditions. In the resulting amorphous phase, Al remains tetrahedrally coordinated, but the micropore volume and concentration of accessible acid sites is reduced dramat...

Journal ArticleDOI
TL;DR: This work presents a first implementation of optical-frequency-comb-based rapid trace gas detection in the molecular fingerprint region in the mid-infrared and achieves part-per-billion detection limits in 30 seconds of integration time for several important molecules.
Abstract: We present a first implementation of optical-frequency-comb-based rapid trace gas detection in the molecular fingerprint region in the mid-infrared Near-real-time acquisition of broadband absorption spectra with 00056 cm(-1) maximum resolution is demonstrated using a frequency comb Fourier transform spectrometer which operates in the 2100-to-3700-cm(-1) spectral region We achieve part-per-billion detection limits in 30 seconds of integration time for several important molecules including methane, ethane, isoprene, and nitrous oxide Our system enables precise concentration measurements even in gas mixtures that exhibit continuous absorption bands, and it allows detection of molecules at levels below the noise floor via simultaneous analysis of multiple spectral features

Journal ArticleDOI
TL;DR: It is shown that an unexpected dialkyl ketone is formed during the synthesis process via a decarboxylative coupling route and provides oxidative conditions which are responsible for the oxidation of the InP core surface and has a significant impact on the photoluminescence properties of the as-synthesized QDs.
Abstract: Advanced 1H, 13C, and 31P solution and solid-state NMR studies combined with IR spectroscopy were used to probe, at the molecular scale, the composition and the surface chemistry of indium phosphide (InP) quantum dots (QDs) prepared via a non-coordinating solvent strategy. This nanomaterial can be described as a core−multishell object: an InP core, with a zinc blende bulk structure, is surrounded first by a partially oxidized surface shell, which is itself surrounded by an organic coating. This organic passivating layer is composed, in the first coordination sphere, of tightly bound palmitate ligands which display two different bonding modes. A second coordination sphere includes an unexpected dialkyl ketone and residual long-chain non-coordinating solvents (ODE and its isomers) which interact through weak intermolecular bonds with the alkyl chains of the carboxylate ligands. We show that this ketone is formed during the synthesis process via a decarboxylative coupling route and provides oxidative conditi...

Journal ArticleDOI
TL;DR: In this paper, a modified titration (Boehm's) process was used to quantify functional groups formed on the surface of oxidized multiwalled carbon nanotubes (MWCNTs).

Journal ArticleDOI
TL;DR: Investigation of molecular interactions between water and EMIES showed that the hydrogen bond involving the -SO(3) group in the ethyl sulfate anion (ES) was enhanced, while those involving the aromatic C-H groups of 1-ethyl-3-methylimidazolium cation (EMI) were weakened in the presence of water.
Abstract: 1-Ethyl-3-methylimidazolium ethyl sulfate (EMIES) is a novel ionic liquid with potential industrial applications. Attenuated total reflectance infrared spectroscopy, 1H NMR spectroscopy, and quantum chemical calculations were employed to investigate the molecular interactions between water and EMIES. The infrared spectra were analyzed by two methods: excess spectroscopy and two-dimensional correlation spectroscopy. This showed that the hydrogen bond involving the −SO3 group in the ethyl sulfate anion (ES) was enhanced, while those involving the aromatic C−H groups of 1-ethyl-3-methylimidazolium cation (EMI) were weakened in the presence of water. During the process of increasing water concentration, the hydrogen bonding interaction between H2O and SO is prior to that between H2O and the C−H group on the imidazolium ring. At low concentrations, water interacts selectively with −SO3 in the ethyl sulfate anion, while, at high concentrations (mole fraction of water equal or greater than 0.6), it can also form...

Journal ArticleDOI
TL;DR: In this article, the photocatalytic activity of the prepared ZnO nanoparticles has been investigated for the degradation of ciprofloxacin drug under UV light irradiation in aqueous solutions of different pH values.

Journal ArticleDOI
Tao Yuan1, Xing Yu1, Rui Cai1, Yingke Zhou1, Zongping Shao1 
TL;DR: Pristine and carbon-coated Li 4 Ti 5 O 12 oxide electrodes are synthesized by a cellulose-assisted combustion technique with sucrose as organic carbon source and their low-temperature electrochemical performance as anodes for lithium-ion batteries are investigated as mentioned in this paper.

Journal ArticleDOI
TL;DR: Experimental results indicated that samarium doping inhibited the growth of crystalline size and the transformation from anatase to rutile phase and the degradation of salicylic acid under visible light irradiation.

Journal ArticleDOI
TL;DR: In this paper, stable aqueous suspensions of graphene (G) nanosheets with high concentration (0.6−2 mg/mL) were prepared through chemical reduction of exfoliated graphite oxide (EGO) with the aid of sodium lignosulfonate (SLS), sodium carboxymethyl cellulose (SCMC), and pyrene-containing hydroxypropyl cellulose(HPC-Py).
Abstract: Stable aqueous suspensions of graphene (G) nanosheets with high concentration (0.6−2 mg/mL) were prepared through chemical reduction of exfoliated graphite oxide (EGO) with the aid of sodium lignosulfonate (SLS), sodium carboxymethyl cellulose (SCMC), and pyrene-containing hydroxypropyl cellulose (HPC-Py). The noncovalently functionalized graphene nanosheets with a 3.3 ± 1.4 nm average thickness were characterized with use of UV−vis spectroscopy, fluorescence spectroscopy, atomic force microscopy, attenuated total reflectance micro-Fourier transform infrared spectroscopy, and Raman spectroscopy.

Journal ArticleDOI
TL;DR: The experimental results in combination with density functional theory calculations provide compelling evidence for the formation of crystalline, double-layer sheet silica weakly bound to a metal substrate.
Abstract: Thin SiO₂ films were grown on a Ru(0001) single crystal and studied by photoelectron spectroscopy, infrared spectroscopy and scanning probe microscopy. The experimental results in combination with density functional theory calculations provide compelling evidence for the formation of crystalline, double-layer sheet silica weakly bound to a metal substrate.

Journal ArticleDOI
Zhi-You Zhou1, Qiang Wang1, Jian-Long Lin1, Na Tian1, Shi-Gang Sun1 
TL;DR: In this paper, a polycrystalline Pd disk electrode in alkaline media was studied by in situ Fourier transform infrared (FTIR) reflection spectroscopy, which revealed that most of ethanol was incompletely oxidized to acetate.

Journal ArticleDOI
29 Apr 2010-Langmuir
TL;DR: It is proposed the binding of the N719 dye to TiO(2) to occur through two neighboring carboxylic acid/carboxylate groups via a combination of bidentate-bridging and H-bonding involving a donating group from the N 719 (and/or Ti-OH) units and acceptor from the Ti- OH (and-or N-719) groups.
Abstract: Vibrational spectroscopic studies of N719 dye-adsorbed TiO2 films have been carried out by using SERRS, ATR-FTIR, and confocal Raman imaging. The high wavenumber region (3000−4000 cm−1) of dye adsorbed TiO2 is analyzed via Raman and IR spectroscopy to investigate the role of surface hydroxyl groups in the anchoring mode. As a complementary technique, confocal Raman imaging is employed to study the distribution features of key dye groups (COO-, bipyridine, and C═O) on the anatase surface. Sensitized TiO2 films made from two different nanocrystalline anatase powders are investigated: a commercial one (Dyesol) and our synthetic variety produced through aqueous synthesis. It is proposed the binding of the N719 dye to TiO2 to occur through two neighboring carboxylic acid/carboxylate groups via a combination of bidentate-bridging and H-bonding involving a donating group from the N719 (and/or Ti-OH) units and acceptor from the Ti-OH (and/or N719) groups. The Raman imaging distribution of COO−sym on TiO2 was used...

Journal ArticleDOI
TL;DR: Mn 3 O 4 thin films have been prepared by novel chemical successive ionic layer adsorption and reaction (SILAR) method by means of X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), field emission scanning electron microscopy (FESEM), wettability test and optical absorption studies as mentioned in this paper.

Journal ArticleDOI
TL;DR: A comparison of the adsorption of water, methanol, and ethanol polar vapors by the flexible porous chromium(III) terephthalate MIL-53(Cr) was investigated by complementary techniques including adsorptive gravimetry, ex situ X-ray powder diffraction, microcalorimetric, thermal analysis, IR spectroscopy, and molecular modeling.
Abstract: A comparison of the adsorption of water, methanol, and ethanol polar vapors by the flexible porous chromium(III) terephthalate MIL-53(Cr) was investigated by complementary techniques including adsorption gravimetry, ex situ X-ray powder diffraction, microcalorimetry, thermal analysis, IR spectroscopy, and molecular modeling. The breathing steps observed during adsorption strongly depend on the nature of the vapor. With water, a significant contraction of the framework is observed. For the alcohols, the initial contraction is followed by an expansion of the framework. A combination of IR analysis, X-ray diffraction, and computer modeling leads to the molecular localization of the guest molecules and to the identification of the specific guest−guest and host−guest interactions. The enthalpies of adsorption, measured by microcalorimetry, show that the strength of the interactions decreases from ethanol to water. Differential scanning calorimetry experiments on an EtOH/H2O mixture suggest a selective adsorpti...

Journal ArticleDOI
TL;DR: In this article, the structural transformation of nanostructured NiFe2O4 using x-ray diffraction (XRD), Mossbauer and magnetization measurements, and Fourier transform infrared (FTIR) and micro-Raman spectroscopy was investigated.
Abstract: Single crystalline nickel ferrite (NiFe2O4) which has an inverse spinel structure is reported to exhibit a mixed spinel structure when its grain size is reduced to nanometer range. It is known that structural transformations in the nanosize regime are not akin to those of bulk crystals. Additionally, magnetic properties like superparamagnetism and contribution to it by surface layers are critically influenced by the synthesis route of the samples. In this article, we present an investigation on the structural transformation of nanostructured NiFe2O4 using x-ray diffraction (XRD), Mossbauer and magnetization measurements, and Fourier transform infrared (FTIR) and micro-Raman spectroscopy. Nanostructured NiFe2O4 samples were synthesized by a coprecipitation technique followed by thermal processing. Four samples having average grain sizes 13, 20, 26, and 51 nm were synthesized. XRD results confirmed the samples to be nanostructured NiFe2O4 and gave evidence for the mixed spinel structure of the samples of lo...

Journal ArticleDOI
TL;DR: In this paper, a series of CuO/CexZr1−xO2 catalysts with different copper loadings and Ce/Zr molar ratios were evaluated to evaluate the correlation of their structural characteristics with catalytic performance.