Fourier Transform Infrared Measurements Research Articles

Magnetic and structural properties of RE doped Co-ferrite (REåNd, Eu, and Gd) nano-particles synthesized by co-precipitation

Cobalt ferrite nano-particles, Co0.9RE0.1Fe2O4, with three different rare earth ions (Nd, Eu, and Gd) were prepared by the chemical co-precipitation method. X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), Fourier Transform Infrared (FTIR), and Vibrating Sample Magnetometry were carried out to study the structural and magnetic properties, respectively. The XRD results revealed that the crystal size is about 22nm for Gd–Co ferrite, which is close to the particle sizes observed from TEM images (20nm). The FTIR measurements between 350 and 4000cm−1 confirmed the intrinsic cation vibrations of the spinel structure. The results showed that the RE ions increase both vibrational frequencies and bond strength. The magnetic results showed that the highest magnetic coercivity and the loop area correspond to the Gd–Co ferrite, making it suitable for hyperthermia treatment. Also, the Curie point was decreased by the RE ions and had its lowest value for Nd–Co ferrite (336°C).

${\rm He}\hbox{-}{\rm H}_{2}{\rm O}_{2}$ Plasma Jet Irradiation of Tissue Surfaces: Study of Dominant Pathways For Plasma Chemical Tissue Removal

Surface tissue-removal mechanisms, resulting from atmospheric He-H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> plasma jet fluxes impinging on tissue surfaces, were investigated. We employed primarily optical emission for cataloging relative concentrations of reactive plasma radicals versus plasma-jet conditions. The reactive radicals were then correlated with measured tissue-removal rates, under varying experimental conditions to determine the dominant role of OH radicals in the tissue removal. Fourier transform infrared (FTIR) molecular spectroscopy was employed to track molecular bond alterations at tissue surfaces, following the plasma irradiation of tissue surfaces. We studied three types of samples: 1) volatilized tissue fragments, filtered out of the effluent; 2) remaining solid-phase tissue samples in the incision region; and 3) nonprocessed contiguous tissue-surface regions. All surface bondings were compared and contrasted by FTIR analysis. In parallel, both the pure electro surgery (ES) with no added plasma radical fluxes and plasma-assisted ES were used as a dual baseline. This three-part study provides evidence that OH radicals drive the observed changes on tissue surfaces both within, and in bordering tissue regions in a He-H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> atmospheric plasma jet. Moreover, plasma-assisted ES as compared to pure ES reduces buildup of tissue char on the ES device electrodes, which is a practical advantage in ES surgery. FTIR measurement of the surgical margins (surrounding the removed tissue) is possible in pure plasma-jet tissue removal, via measuring changes in amide A bonds, which are indicators of the level of thermal damage to surrounding tissue, and may be a possible control means to achieve minimum collateral damage.

A novel direct coupling of simultaneous thermal analysis (STA) and Fourier transform-infrared (FT-IR) spectroscopy

Evolved gas analysis (EGA) from thermal analyzers such as thermogravimetry (TG) or simultaneous thermal analysis (STA) which refers to simultaneous TG–DSC is well established since it greatly enhances the value of TG or TG–DSC results. The sensitive and selective FT-IR technique is in particular useful for the analysis of organic molecules but also for infrared active permanent gases evolved during most decomposition processes. The coupling interface between thermal analyzers and FT-IR spectrometers usually consists of heated adapters and a flexible, heated transfer line. In this work, a novel direct coupling of an STA instrument and an FT-IR spectrometer without a transfer line is presented. A very small FT-IR spectrometer is directly mounted on top of the STA furnace leading to a compact and fully integrated STA–FT-IR coupling system. The possibilities and the value of simultaneous STA–FT-IR measurements are demonstrated for organic, biomass, and ceramic samples in the temperature range between room temperature and about 1,500 °C. Various samples from the field of inorganics and organics—especially polymers—were furthermore measured showing the advantages of the direct STA–FT-IR coupling compared to state-of-the-art STA–FT-IR coupling using a heated transfer line: we found that the time delay caused by the volume of the transfer line itself is rather negligible whereas a significantly better correlation between gas detection and TG results was observed in case of some highly condensable decomposition gases. Aspects of quantification of evolved gases are furthermore discussed as well as the known nonlinearity of FT-IR detection at higher gas concentrations.

Interactions of a cationic surfactant – (benzyloxymethyl) dodecyldimethylammonium chloride with model biomembrane systems

Phospholipids are the main components of biological membranes. The aim of the present study was to determine the influence of a cationic surfactant on phospholipid structure and dynamics. Fourier transform infrared (FTIR) and dielectric relaxation (DRS) spectroscopies as well as small-angle X-ray scattering (SAXS) with synchrotron radiation have been used to analyse the structure of fully hydrated 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) in the presence of a quaternary ammonium surfactant: (benzyloxymethyl) dodecyldimethylammoniumchloride (BzMDDAC). The presence of the surfactant caused changes in the temperature of the DMPC phase transition, as revealed using FTIR and DRS measurements. This change results from the disappearance of the multilamellar phase of DMPC and the formation of the unilamellar (most likely bicellar) phase, as indicated by the SAXS results.

Detection of Distinct α-Helical Rearrangements of Cyclobutane Pyrimidine Dimer Photolyase upon Substrate Binding by Fourier Transform Infrared Spectroscopy

Photolyases (PHRs) utilize near-ultraviolet (UV)-blue light to specifically repair the major photoproducts (PPs) of UV-induced damaged DNA. The cyclobutane pyrimidine dimer PHR (CPD-PHR) from Escherichia coli binds flavin adenine dinucleotide (FAD) as a cofactor and 5,10-methenyltetrahydrofolate as a light-harvesting pigment and specifically repairs CPD lesions. By comparison, a second photolyase known as (6-4) PHR, present in a range of higher organisms, uniquely repairs (6-4) PPs. To understand the repair mechanism and the substrate specificity that distinguish CPD-PHR from (6-4) PHR, we applied Fourier transform infrared (FTIR) spectroscopy to bacterial CPD-PHR in the presence or absence of a well-defined DNA substrate, as we have studied previously for vertebrate (6-4) PHR. PHRs show light-induced reduction of FAD, and photorepair by CPD-PHR involves the transfer of an electron from the photoexcited reduced FAD to the damaged DNA for cleaving the dimers to maintain the DNA's integrity. Here, we measured and analyzed difference FTIR spectra for the photoactivation and DNA photorepair processes of CPD-PHR. We identified light-dependent signals only in the presence of substrate. The signals, presumably arising from a protonated carboxylic acid or the DNA substrate, implicate conformational rearrangements of the protein and substrate during the repair process. Deuterium exchange FTIR measurements of CPD-PHR highlight potential differences in the photoactivation and photorepair mechanisms in comparison to those of (6-4) PHR. Although CPD-PHR and (6-4) PHR appear to exhibit similar overall structures, our studies indicate that distinct conformational rearrangements, especially in the α-helices, are initiated within these enzymes upon binding of their respective DNA substrates.

Mechanism of Low-Temperature CO Oxidation on Pt/Fe-Containing Alumina Catalysts Pretreated with Water

In a previous article (Catal. Commun. 2012, 17, 194), we reported that Pt/Fe-containing alumina catalysts pretreated with water could catalyze CO oxidation even below room temperature. To clarify the effect of the water pretreatment and the reaction mechanism of the novel catalytic system, in situ Fourier transform infrared (FT-IR), and X-ray absorption fine structure (XAFS) measurements during CO oxidation were conducted. From FT-IR measurements, it was revealed that the Pt surface of the catalyst was covered with CO and that the adsorbed CO molecules did not desorb easily, as in the case of conventional Pt/Al2O3 catalyst. Pt LIII XAFS results also suggested the presence of CO on the Pt surface during CO oxidation. Thresholds of Fe K X-ray absorption near-edge structure shifted with the change between oxidative (0.5% O2/He) and reductive (1% CO/He) atmospheres, indicating that the Fe redox change Fe2+ ↔ Fe3+ can participate in the reaction. From the degree of the shifts and average Pt diameters derived from high-angle annular dark-field scanning transmission electron microscopy and metal dispersion measurements, it was concluded that PtNP/FeOx boundaries were efficiently formed upon the water pretreatment. The enhanced reactivity of the water-pretreated catalyst can be attributed to the increased number of boundaries and Pt diameter.

Evaluation for the Mixing Performance of a Microreactor with Inline Measurement

We have evaluated the mixing performance of a microreactor with inline ultraviolet (UV) and Fourier transform-infrared (FT-IR) measurement. We performed the well-known Villermaux–Dushman reaction with inline and o ine UV measurements. Absorbance was continuously reproduced at each ow rate with inline measurement. The di erence between the inline and o ine measurement results was within ±5% at faster ow rates than 2 mL/min. However, the di erence between the inline and o ine measurement results at 1 mL/min occurred because the sample changed until the start of o ine measurement. It is shown that “real-time” monitoring and more accurate analyses were performed with this inline measurement system. We have also performed the methanol–ethanol mixing process with inline FT-IR measurement. The absolute slope of absorbance peak height with changing from methanol to a mixing solution became larger as the ow rate increased, while it hardly changed at faster ow rates than 10 mL/min (1.0×10−5 m3/min).This suggests that the mixing performance improved as the ow rate increased, while the mixing performance was saturated at faster ow rates. The tendency in the mixing performance was in good agreement with that obtained from the Villermaux–Dushman reaction. Therefore, it has been con rmed that the mixing performance of microreactors could be appropriately evaluated with inline UV or FT-IR measurement.

Proton infiltration of phosphosilicate glass-electrolytes for intermediate temperature fuel cell

ABSTRACTA fast proton conducting glass with proton transport number tH = 1 was successfully prepared by using conventional melting method. In-situ FTIR (Fourier transform infrared) measurements under hydrogen atmosphere, temperature of 300°C and applying 1 V between Pt electrodes were carried out in order to monitor the proton concentration. The electrode reaction on Pt in these conditions is similar to that under intermediate-temperature fuel cell operation. It was found from the in-situ FTIR measurements that the absorbance around 2900 cm-1 increases clearly after applying 1 V, whereas no significant change was observed around 3400 cm-1. Proton infiltration into the glass is discussed based on the in-situ FTIR and impedance results.

Conformation aspect in the α-amylase induced agglomeration of citrate-stabilized gold nanoparticles

In this article we report the effect of a chemical denaturant on the agglomeration behaviour of a citrate stabilized Au NP–protein composite. We have used α-amylase as a model protein and urea as the chemical denaturant. The agglomeration behaviour has been studied by UV-Visible and Fourier transform infrared (FTIR) spectroscopy, circular dichroism (CD), dynamic light scattering (DLS) based particle size analyses, fluorescence studies, zeta potential measurements and transmission electron microscopy (TEM). Our studies indicate that when α-amylase was added to a cit–Au NP dispersion, agglomerated structures were formed whose sizes increased with time. On the other hand, when urea was also added, the agglomerated structures did not grow further indicating that the agglomeration process was arrested. In addition, urea was found to permeate to the surface of Au NPs in the agglomerated units, as seen by changes in the UV-Vis spectra, zeta potential measurements, FTIR and fluorescence measurements. Results of CD and FTIR studies are indicative of the α-helix of the protein being stabilized in the cit–Au NP induced conformational changes of α-amylase leading to its agglomeration. The activity of the proteins present in the agglomerated structures was still retained. Interestingly, addition of chemically denatured protein (urea treated α-amylase) to the cit–Au NP–protein composite did not result in further agglomeration of the composite. The observations reported herein indicate that the interaction between the cit–Au NP and the protein leading to agglomeration is dependent on the conformation of the protein, and that while native protein was involved in the agglomeration process, denatured protein was not involved in agglomeration process. Urea induced unfolding of the free proteins as well as the presence of ions in the medium stopped or stalled the growth of the agglomerated structures.

Optical Absorption, Photoluminescence, and Raman Scattering Studies on Si Nanowire Arrays Formed in Ag2SO4−HF−H2O Solution

Vertically well-aligned Si nanowire (SiNW) arrays were synthesized by catalytic etching in a newly developed etchant system Ag2SO4−HF−H2O. The structural and optical properties of the synthesized SiNW arrays were investigated by scanning electron microscopy observation, Fourier-transform infrared (FTIR) spectroscopy analysis, near-IR−UV transmittance, Raman scattering, and photoluminescence (PL) measurements. The FTIR and transmittance measurements revealed that the SiNW arrays show about two or three orders lower optical transmittances in the far-IR−UV region than those for the single-crystalline Si substrate. The Raman intensities and spectral features were also found to be clearly different from those for the bulk single-crystalline Si. Such Raman scattering data were analyzed using a modified Lorentzian model with introducing an exponential asymmetry factor. Results were in satisfactory agreement with the experimental spectra. The SiNWs formed in the conventional AgNO3 solutions emitted lights in the red spectral region; however, no PL emission was observed from the Ag2SO4-synthesized SiNW array. This fact suggests that the Ag2SO4-synthesized nanowire sidewalls should be much smoother than the conventional AgNO3-synthesized ones.

Secondary structure of proteins analyzed ex vivo in vascular wall in diabetic animals using FT-IR spectroscopy

In recent years many methods for ex vivo tissue analysis or diagnosis of diseases have been applied, including infrared absorption spectroscopy. Fourier-transform infrared (FT-IR) absorption microspectroscopy allows the simultaneous monitoring of the content of various chemical compounds in tissues with both high selectivity and resolution. Imaging of tissue samples in very short time can be performed using a spectrometer equipped with a Focal Plane Array (FPA) detector. Additionally, a detection of minor components or subtle changes associated with the functional status of a tissue sample is possible when advanced methods of data analysis, such as chemometric techniques, are applied. Monitoring of secondary structures of proteins has already proved to be useful in the analysis of animal tissues in disease states. The aim of this work was to build a mathematical model based on FT-IR measurements for the prediction of alterations in the content of secondary structures of proteins analyzed by FT-IR in the vascular wall of diabetic animals. For that purpose a spectral database of proteins of known crystallography and secondary structures was assembled. Thirty-seven proteins were measured by means of two FT-IR techniques: transflection and Attenuated Total Reflectance (ATR). The obtained model was tested on cross-sections of rat tail, for which the content of proteins and their secondary structures was well characterized. Then, the model was applied for the detection of possible alterations in the secondary structures of proteins in the vascular wall of diabetic rats and mice. The obtained results suggest a prominent increase in E- and S-structures and a decrease in the content of H-structures in the vascular wall from diabetic mice and rats. FT-IR-based studies of secondary structures of proteins may be a novel approach to study complex processes ongoing in the vascular wall. The obtained results are satisfactory; however, the existing limitations of the method are also discussed.

Detection of fungal infection in Lolium perenne by Fourier transform infrared spectroscopy

Aims The goal of the study was to apply Fourier transform infrared (FTIR) spectroscopy followed be chemometrical data treatment for the differentiation of fungi-infected perennial ryegrass (Lolium perenne) from non-infected grass. Methods FTIR was used to rapidly discriminate between leaves of perennial ryegrass (Lolium perenne) infected by a fungal endophyte (Epichloe; asexual forms: Neotyphodium) and uninfected leaves. Besides drying and grinding of the sampled leaves, no other preparation steps were needed. FTIR measurements were performed in the attenuated total reflection (ATR) mode. Aliquots of powdered leaf samples were placed on a ZnSe crystal and the spectra collected followed by chemometrical analysis (multidimensional factor analysis, hierarchical cluster analysis). Important Findings ATR-FTIR allowed a rapid detection of fungal infections in the plant material and proved to be a fast and reliable tool for the differentiation of the plant biomass without the need of time-consuming sample preparation.

FTIR time-series of biomass burning products (HCN, C&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;H&amp;lt;sub&amp;gt;6&amp;lt;/sub&amp;gt;, C&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;, CH&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;OH, and HCOOH) at Reunion Island (21° S, 55° E) and comparisons with model data

Abstract. Reunion Island (21° S, 55° E), situated in the Indian Ocean at about 800 km east of Madagascar, is appropriately located to monitor the outflow of biomass burning pollution from Southern Africa and Madagascar, in the case of short-lived compounds, and from other Southern Hemispheric landmasses such as South America, in the case of longer-lived species. Ground-based Fourier transform infrared (FTIR) solar absorption observations are sensitive to a large number of biomass burning products. We present in this work the FTIR retrieval strategies, suitable for very humid sites such as Reunion Island, for hydrogen cyanide (HCN), ethane (C2H6), acetylene (C2H2), methanol (CH3OH), and formic acid (HCOOH). We provide their total columns time-series obtained from the measurements during August–October 2004, May–October 2007, and May 2009–December 2010. We show that biomass burning explains a large part of the observed seasonal and interannual variability of the chemical species. The correlations between the daily mean total columns of each of the species and those of CO, also measured with our FTIR spectrometer at Reunion Island, are very good from August to November (R &amp;amp;geq; 0.86). This allows us to derive, for that period, the following enhancement ratios with respect to CO: 0.0047, 0.0078, 0.0020, 0.012, and 0.0046 for HCN, C2H6, C2H2, CH3OH, and HCOOH, respectively. The HCN ground-based data are compared to the chemical transport model GEOS-Chem, while the data for the other species are compared to the IMAGESv2 model. We show that using the HCN/CO ratio derived from our measurements (0.0047) in GEOS-Chem reduces the underestimation of the modeled HCN columns compared with the FTIR measurements. The comparisons between IMAGESv2 and the long-lived species C2H6 and C2H2 indicate that the biomass burning emissions used in the model (from the GFED3 inventory) are probably underestimated in the late September–October period for all years of measurements, and especially in 2004. The comparisons with the short-lived species, CH3OH and HCOOH, with lifetimes of around 5 days, suggest that the emission underestimation in late September–October 2004, occurs more specifically in the Southeastern Africa-Madagascar region. The very good correlation of CH3OH and HCOOH with CO suggests that, despite the dominance of the biogenic source of these compounds on the global scale, biomass burning is their major source at Reunion Island between August and November.

Evaluation of a setting reaction pathway in the novel composite TiHA–CSD bone cement by FT-Raman and FT-IR spectroscopy

The aim of this study was to determine a setting reaction pathway in a novel, surgically handy implant material, based on calcium sulfate hemihydrate (CSH) and titanium doped hydroxyapatite (TiHA). The previous studies confirmed superior biological properties of TiHA in comparison to the undoped hydroxyapatite (HA) what makes it highly attractive for future medical applications. In this study the three types of titanium modified HA powders: untreated, calcined at 800°C, sintered at 1250°C and CSH were used to produce bone cements. The Fourier Transform-InfraRed (FT-IR) spectroscopy and Raman spectroscopy were applied to evaluate processes taking place during the setting of the studied materials. Our results undoubtedly confirmed that the reaction pathways and the phase compositions differed significantly for set cements and were dependent on the initial heat treatment of TiHA powder. Final materials were multiphase composites consisting of calcium sulfate dihydrate, bassanite, tricalcium phosphate, hydroxyapatite and calcium titanate (perovskite). The FT-IR and Scanning Electron Microscopy (SEM) measurements performed after the incubation of the cement samples in the simulated body fluid (SBF), indicate on high bioactive potential of the obtained bone cements.

Electrical, optical and structural investigation of plasma-enhanced chemical-vapor-deposited amorphous silicon oxynitride films for solar cell applications

Hydrogenated amorphous silicon oxynitride (a-SiOxNy:H) films, which are deposited by the plasma decomposition of silane and nitrous oxide at low temperatures (Tdep<300°C), are investigated in order to evaluate the potential of these films for photovoltaic applications. In this work both, intrinsic and doped a-SiOxNy:H films are investigated in terms of their electrical, optical and structural properties using Fourier-transform infra-red (FTIR) and secondary-ion mass-spectroscopy (SIMS), as well as high-resolution transmission electron microscopy (HRTEM), photo-conductance decay (PCD), spectral ellipsometry and temperature-dependent conductivity measurements. The plasma deposition parameters are optimized in terms of effective minority carrier lifetime, dark conductivity and low absorbance (i.e. high optical band gap). The optical band gap of the a-SiOxNy:H films can be widened up to 2.2eV compared to a-Si:H due to the incorporation of oxygen and nitrogen into the amorphous network. Not only the optical band gap but also the passivation quality and the dark conductivity of the films are well correlated with the oxygen and nitrogen concentration, which are monitored by means of SIMS measurements. When applying an a-SiOxNy:H film with an optical band gap of 2.0eV, a very high effective minority carrier lifetime of 2.5ms is measured. In case of doped films, conductivities up to σdark=4.5×10−3S/cm for the n-type doping and σdark=3.9×10−4S/cm for the p-type doping are achieved. Combining the intrinsic and doped a-SiOxNy:H films to heteroemitter stacks on a crystalline Si base, a very high implied open circuit voltage of up to 733mV is demonstrated. FTIR and HRTEM measurements reveal a homogenous distribution of Si–Si and Si–O–Si bonds in the a-SiOxNy:H films.

Photodegradation of thermally modified wood

Natural wood, being biological material, undergoes rapid degradation by ultraviolet (UV) radiations and other environmental factors under outdoor exposure. In order to protect wood from such degradation, the chemical structure of wood is altered by chemical modification or heat treatment. In the present study, heat treated specimens of rubberwood (Hevea brasiliensis) were exposed to xenon light source in a weather-o-meter for different periods up to 300h. Photostability of modified and unmodified wood was evaluated in terms of colour and chemical changes. Light coloured untreated wood became dark upon UV irradiation whereas, dark colour of heat treated wood lightened on UV exposure. CIE lightness parameter (L*) decreased for untreated wood whereas its value increased for heat treated wood upon irradiation. Other colour coordinates a* and b* increased with exposure duration for both untreated and heat treated wood. The overall colour change (ΔE*) increased for both untreated and heat treated wood. The Fourier Transform Infrared (FTIR) spectroscopic studies revealed severe lignin degradation of heat treated wood due to UV light exposure. Colour changes and FTIR measurements indicate that thermal modification of wood was ineffective in restricting light induced colour changes and photodegradation of wood polymers.

The roles of hydrogen in the diamond/amorphous carbon phase transitions of oxygen ion implanted ultrananocrystalline diamond films at different annealing temperatures

We report that the diffusion and desorption of hydrogen (H) play a key role in the diamond/amorphous carbon phase transitions of O+-implanted UNCD films at different annealing temperatures (Ta) by using high resolution transmission electronic microscopy (HRTEM), vis-uv Raman, and Fourier transform infrared (FTIR) spectroscopy measurements. The results of HRTEM and uv Raman spectroscopy measurements show that with Ta increasing from 500 to 900 °C, the amorphous carbon in grain boundaries (GBs) transits to diamond phase. Visible Raman spectroscopy measurements show that the amount of H bonded to trans-polyacetylene (TPA) chains in GBs reduces with Ta increasing to 900 °C, while that of H terminating to the surfaces of diamond grains increases confirmed by FTIR measurements. It reveals that H diffuses from GBs to the surfaces of diamond grains. In this process, the active H extracts H which terminates the diamond surface, leaving a reactive surface site. This gives a chance for the neighbored amorphous carbon clusters to attach to the surface site, so that diamond grains become larger. After 1000 °C annealing, the amount of diamond phase dramatically decreases and diamond transits to amorphous carbon by HRTEM and uv Raman spectroscopy. It is observed that the amount of H bonded to TPA chains in GBs and that of H terminating to the surfaces of diamond grains dramatically decreases from visible Raman spectroscopy and FTIR measurements. It is revealed that H is desorbed from both surfaces of diamond grains and GBs, which forces diamond grains to collapse to amorphous carbon.

Calorimetric, FTIR and 1H NMR measurements in combination with DFT calculations for monitoring solid‐state changes of dynamics of sibutramine hydrochloride

Two forms of sibutramine hydrochloride, monohydrate and anhydrous, have been investigated by calorimetric methods, Fourier transform infrared (FTIR) absorption and (1) H nuclear magnetic resonance (NMR) measurements as well as by density functional theory (DFT) of vibrational frequencies and infrared intensities, calculations of steric hindrances and Monte Carlo simulations. The results of FTIR spectra combined with DFT calculations permitted identification of the bands corresponding to the dynamics and vibrations of water molecules. NMR study and Monte Carlo simulations revealed the occurrence of reorientation jumps of the methyl groups in sibutramine cation and also revealed that the reorientation of isopropyl group is possible only in sibutramine monohydrate hydrochloride. The hydration of sibutramine hydrochloride causes a change in the conformation of sibutramine cation.

Photodegradation of an azo dye with reusable SrF2–TiO2 under UV light and influence of operational parameters

SrF2 loaded TiO2 (SrF2–TiO2), prepared by sol–gel method, was characterized by Fourier transform infrared (FT-IR) spectra, scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), diffuse reflectance spectra (DRS), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), atomic force microscopy (AFM) and BET surface area measurements. TEM images reveal that the sizes of SrF2–TiO2 particles are in the range of 3–20nm. Presence of metal halide (SrF2) in the catalyst was confirmed by FT-IR, XRD, XPS and CV measurements. SrF2 loading increases the absorption of UV and visible light. AFM images show a cavity which increases the surface area and photocatalytic activity of the catalyst. 3wt% SrF2 loaded TiO2 was found to be more photoactive than bare TiO2 in Reactive Yellow 84 (RY 84) dye degradation. The effects of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photomineralization by SrF2–TiO2 have been analyzed. The optimum pH and catalyst amount for efficient removal of dye are found to be 5 and 4gL−1, respectively. The intermediates identified by GC–MS analysis during photodegradation, are 2-amino-4-[(4-amino-6-chloro-1,3,5-triazin-2-yl)amino]phenol (1), 6-chloro-N-phenyl-1,3,5-triazin-2,4-diamine (2), 2,4-diaminophenol (3) and 1,3,5-triazin-2,4-diamine (4) based on their molecular ion and mass spectrometric fragmentation peaks. The mineralization of RY 84 has also been confirmed by CV and chemical oxygen demand (COD) measurements. Mechanism of dye degradation by SrF2–TiO2 is proposed on the basis of hole trapping property of SrF2. The catalyst was found to be stable and reusable.

Understanding the VOC sorption processes on fluoro alkyl substituted phthalocyanines using ATR FT-IR spectroscopy and QCM measurements

Abstract In this work the sorption of volatile organic compounds (VOCs) by phthalocyanines is studied and modelled using in situ attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy and gas sensor data. A series of fluoropropoxyphthalocyanines (Pcs) either in the metal free form or as nickel and cobalt complexes were synthesised and coated on quartz crystal microbalance and ZnSe ATR substrates as thin films with the jet spray technique. The VOCs for the gas exposure experiments were selected according to their physico-chemical properties such as acidity, basicity, polarity etc. The influence of the humidity on the interaction mechanism and the sensor signal was also investigated. The in detail analysis of the ATR FT-IR measurements revealed that the analytes interact mainly with the centre of the Pcs (a metal ion or N H group), the aromatic CH group of the Pc core, and the substituent group. The aromatic C H groups of the Pc core were identified as active centres for the first time and were found to play an active role in the sensing mechanism and determine the sensitivity of the sensors. They may interact with a π system of an analyte via H π bonding or with OH groups via hydrogen bonds.