Fourier Transform Infrared Absorption Research Articles

Interactions of the Anticancer Drug Tamoxifen with Lipid Membranes

Interactions of the hydrophobic anticancer drug tamoxifen (TAM) with lipid model membranes were studied using calcein-encapsulated vesicle leakage, attenuated total reflection Fourier transform infrared (FTIR) spectroscopy, small-angle neutron scattering (SANS), atomic force microscopy (AFM) based force spectroscopy, and all-atom molecular dynamics (MD) simulations. The addition of TAM enhances membrane permeability, inducing calcein to translocate from the interior to the exterior of lipid vesicles. A large decrease in the FTIR absorption band’s magnitude was observed in the hydrocarbon chain region, suggesting suppressed bond vibrational dynamics. Bilayer thickening was determined from SANS data. Force spectroscopy measurements indicate that the lipid bilayer area compressibility modulus KA is increased by a large amount after the incorporation of TAM. MD simulations show that TAM decreases the lipid area and increases chain order parameters. Moreover, orientational and positional analyses show that TAM exhibits a highly dynamic conformation within the lipid bilayer. Our detailed experimental and computational studies of TAM interacting with model lipid membranes shed new light on membrane modulation by TAM.

Spatio-temporal evolution of the dust particle size distribution in dusty argon rf plasmas

An imaging Mie scattering technique has been developed to measure the spatially resolved size distribution of dust particles in extended dust clouds. For large dust clouds of micrometre-sized plastic particles confined in an radio frequency (rf) discharge, a segmentation of the dust cloud into populations of different sizes is observed, even though the size differences are very small. The dust size dispersion inside a population is much smaller than the difference between the populations. Furthermore, the dust size is found to be constantly decreasing over time while the particles are confined in an inert argon plasma. The processes responsible for the shrinking of the dust in the plasma have been addressed by mass spectrometry, ex situ microscopy of the dust size, dust resonance measurements, in situ determination of the dust surface temperature and Fourier transform infrared absorption (FT-IR). It is concluded that both a reduction of dust size and its mass density due to outgassing of water and other volatile constituents as well as chemical etching by oxygen impurities are responsible for the observations.

Spectroscopic studies of SiOx films irradiated with high energy electrons

The effect of 20 MeV electron irradiation on the vibrational properties of homogeneous SiOx films and SiOx films containing amorphous or crystalline Si nanoparticles is studied. Layers with x = 1.15 and 1.3 and two different thicknesses, 200 nm and 1000 nm, were deposited on crystalline silicon substrates and annealed at 250 °C for stabilization. No nanoparticle growth occurs at this temperature. A part of the films were annealed in an inert atmosphere at 700 °C or 1000 °C for 60 min in order to grow amorphous (a-Si) or crystalline (nc-Si) silicon nanoparticles, respectively. Samples from all types of the films were irradiated with 20 MeV electrons at close to room temperature and a fluence of 2.4×1014 el.cm−2. The effect of the irradiation was investigated by means of Fourier Transform Infrared Absorption (FTIR) and Raman scattering spectroscopy. The FTIR results show no appreciable changes in the composition of the homogeneous SiOx films and the oxygen content in the matrix of a-Si- SiOx composite films. The electron irradiation causes an increase of the intensity of the light scattered from the pure silicon phase. The results obtained are discussed in terms of disorder decrease in the Si nanoparticles stimulated by MeV electron beam irradiation.

Chemically modified reaction centers of photosystem II: Exchange of pheophytin a with 7-deformyl-7-hydroxymethyl-pheophytin b

The native pheophytin a (Pheo a) in isolated reaction centers of photosystem II (PSII RCs) has been chemically exchanged with extraneous 7-deformyl-7-hydroxymethyl-Pheo b (71-OH-Pheo b) which differs from Pheo a by the C-7 substituent (hydroxymethyl instead of methyl). The two pigments have similar reduction potentials in vitro [M. Meyer, Dissertation, Universität München, 1997], while their absorption spectra show small but distinct differences in the visible region. The resulting 71-OH-Pheo b-modified reaction center preparations were characterized by high-performance liquid chromatography, electronic absorption and light-induced Fourier transform infra red absorption difference spectroscopies, together with photoaccumulation of the reduced pheophytin electron acceptor and NaBH4-treatment. About 70% of the total Pheo a molecules are found to be replaced by 71-OH-Pheo b molecules in modified preparations, indicating that both the photochemically active (PheoD1) and inactive (PheoD2) binding sites were subjected to pigment exchange. The 71-OH-Pheo b molecule located at the PheoD1 site is able to functionally replace the native Pheo a, participating in primary charge separation as an electron acceptor. The Qx absorption band of this modified pheophytin molecule is localized at ~546nm; its Qy band is blue-shifted with respect to the absorption of other reaction center core pigments, being located at ~665nm. The Qy and Qx optical transitions of the 71-OH-Pheo b molecule exchanged into the PheoD2 site are identified at 677 and 543.5nm, respectively. The photochemically active double-modified PSII RCs additionally containing 7-deformyl-7-hydroxymethyl-131-deoxo-131-hydroxy-Pheo b at the PheoD2 site were obtained by treatment of the 71-OH-Pheo b-modified RCs with NaBH4.

Fabrication of SDBS intercalated-reduced graphene oxide/polypyrrole nanocomposites for supercapacitors

PPy (polypyrrole)/SDBS (sodium dodecyl benzenesulfonate) intercalated reduced graphene oxide (rGO) nanocomposites (PPy/GSR) were prepared via in situ oxidative polymerization of pyrrole on the SDBS interposed graphene. FE-SEM (field emission scanning microscopy), TEM (transmitting electron microscopy), UV–vis (ultraviolet and visible) absorption spectroscopy, FT-IR (Fourier transform infrared) spectroscopy, XRD (X-ray diffraction) analyzer and TGA (thermogravimetric analysis) instrument were used to characterize the morphology and structure of the samples. The results showed the disordered GSR (SDBS organo modified-rGO) disappeared and rGO existed in the form of individual graphene sheet or stacked layers in PPy matrix. The rGO serves as a support material for nano-sized PPy particles. In addition, CV (cyclic voltammetry), GCD (galvanostatic charge-discharge) and EIS (electrochemical impedance spectroscopy) techniques were used to measure the electrochemical properties with a three-electrode cell measurement. The specific capacitance of the PPy/GSR nanocomposite achieved 277F/g for the PPy/GSR 9:1 sample.

Fourier Transform Infrared Spectral Analysis of Degenerative Human Intervertebral Discs

Introduction Intervertebral disc (IVD) structure changes throughout life ultimately resulting in disc degeneration and back pain. Most of the IVD extracellular matrix alterations are related this degeneration. Fourier transform infrared (FTIR) spectroscopy has been shown to be a powerful tool in the study of molecular changes associated with matrix structure (collagen denaturation, cross-links, proteoglycans [PGs], and calcification). FTIR analysis is based on monitoring vibrations that originate from molecular components in tissues. Accordingly, evaluation of changes in molecular structure, concentration, and spatial distribution of the tissue components can be performed by direct analysis of spectral maps. Once the spectral maps are calculated, the spatial quantitative and qualitative information on the composition and organization of the tissue compounds can be obtained. FTIR has been successfully utilized in bone and cartilage research in the differentiation between normal and diseased tissues. Our study aims to investigate spatial changes in human IVD composition and microstructural organization in relation to increasing grades of degeneration. Materials and Methods Sample Preparation Human IVDs were obtained from donor lumbar spines of Thompson grades 2 to 5 through organ donations within 24 hours after death. Two IVDs per grade of degeneration were used for FTIR procedure. All tissues were fixed in Accustain (Sigma-Aldrich, St. Louis, Missouri, United States), paraffin embedded and sectioned into 20-mm-thick sagittal sections. Consecutive slices were assessed for chemical properties. FTIR Spectra Acquisition Human IVD sections were placed on barium fluoride infrared transparent windows and infrared absorbance spectra were acquired using a classical FTIR spectrometer FTS 7000 series’ (DGILAB) coupled to UMA 600 microscope. For FTIR spectra acquisition, the system was used in point mode (aperture of 250 ×250 µm) with a 4.0/cm resolution and using 128 scans in transmittance mode, and spectra acquisitions were performed under complete N2 purge of the analytical system. Four repeated scans were performed on the spectral region of approximately 900 to 2,000/cm in each sample in the annulus fibrosus (AF) and nucleus pulposus (NP) regions. Analysis of FTIR Absorption Spectrum of IVD Spectral data were analyzed using Wire 3.0 software. All spectra were baselined and the absorbance of the collagen (COL), elastin, and PG were monitored in the 1,690 to 1,660; 1,595 to 1,500; and 1,140 to 985/cm spectral regions. A univariate analysis was used to evaluate the collagen maturity as the ratio of the integrated area under the amide subpeaks (1,660:1,690/cm). Results The elastin and COL content associated with the stretching vibrations of carbonyl (C=O), C-N, and N-H in the amide II spectral region (1,595-1,500/cm) indicated a significant decrease according to degeneration grade (in AF, from 29.73 ± 0.83 in grade 2 to 20.19 ± 0.65 in grade 5, and in NP from 24.92 ± 0.71 in grade 2 to 8.76 ± 0.56 in grade 5). A significant decrease was also found for the PG content, which is reflected by the stretching vibrations of C-O, C-OH, and as C-C in the carbohydrate chemical group. PG content significantly decreased from 7.95 ± 0.89 in grade 2 to 2.77 ± 0.11 in grade 5 ( p < 0.05) in AF, and from 9.2 ± 1.02 in grade 2 to 5.67 ± 0.72 in grade 5 ( p < 0.03) in NP. Moreover, the ratio of the integrated area of the amide subpeaks (1,660:1690/cm) accompanying collagen maturity, doubled in value with increasing degeneration grades. Conclusion Our studies indicate that FTIR spectral imaging, coupled with univariate data processing techniques, can be used to image the spatial distribution of matrix constituents in human discs with different grades of degeneration. It can therefore provide unique quantitative information on how human disc degeneration can affect the functional state of the disc. Disclosure of Interest None declared

Reactive species output of a plasma jet with a shielding gas device—combination of FTIR absorption spectroscopy and gas phase modelling

In this work, a simple modelling approach combined with absorption spectroscopy of long living species generated by a cold atmospheric plasma jet yields insight into relevant gas phase chemistry. The reactive species output of the plasma jet is controlled using a shielding gas device. The shielding gas is varied using mixtures of oxygen and nitrogen at various humidity levels. Through the combination of Fourier transform infrared (FTIR) spectroscopy, computational fluid dynamics (CFD) simulations and zero dimensional kinetic modelling of the gas phase chemistry, insight into the underlying reaction mechanisms is gained. While the FTIR measurements yield absolute densities of ozone and nitrogen dioxide in the far field of the jet, the kinetic simulations give additional information on reaction pathways. The simulation is fitted to the experimentally obtained data, using the CFD simulations of the experimental setup to estimate the correct evaluation time for the kinetic simulation. It is shown that the ozone production of the plasma jet continuously rises with the oxygen content in the shielding gas, while it significantly drops as humidity is increased. The production of nitrogen dioxide reaches its maximum at about 30% oxygen content in the shielding gas. The underlying mechanisms are discussed based on the simulation results.

X-Ray Diffraction and Vibrational Spectroscopic Characteristics of Hydroxylclinohumite from Ruby-Bearing Marbles (Luc Yen District, Vietnam)

A honey-yellow hydroxylclinohumite from ruby-bearing marbles of the Luc Yen district in northern Vietnam was characterized by electron microprobe (EPMA), single-crystal X-ray diffraction (XRD), micro-Raman, and Fourier-transform infrared (FTIR) spectroscopy. The studied crystals correspond to nearly ideal clinohumite with the structural formula 4[Mg2SiO4]·[(Mg,Fe,Ti)(OH,F)2] and roughly equal F and OH proportions. Crystal structure analysis showed Ti substitution for Mg only at the Mg3 site. A Fourier-difference map revealed one hydrogen site associated with ninth oxygen atom. The calculated O–H bond distance was shorter than that in other natural clinohumites. FTIR revealed bands corresponding to combination of OH-stretching with Mg–OH and/or Fe–OH bending modes, combinations of OH−and Fe–OH vibrations, combination of fundamental bands of the Si–OH bonding, combination of OH−and Si–OH vibrations, and first (2νOH) and the second (3νOH) overtones of the OH-stretching vibration mode. Two groups of OH-stretching vibration and FTIR absorption bands at 3390–3420 cm−1and 3560–3580 cm−1show reversible temperature-dependent shift. The low-frequency bands absent in pure synthetic hydroxylclinohumites are assigned to OH-planar defects caused by Ti-for-Mg substitution.

Spectroscopic investigation of synergetic bioactivity behavior of some ternary borate glasses containing fluoride anions

Ternary borate glasses containing LiF, ZnF2, NaF or CaF2 were prepared by full replacement of silica by borate in patented Hench′s bioglass. Prepared samples were examined for their corrosion behavior with the expected final formation of fluoroapatite after immersion in SBF (simulated body fluid). Characterization of the glasses was carried by FTIR (Fourier transform infrared) absorption spectra before and after immersion. DAT (deconvolution analysis technique) was used to identify the formation of fluoroxyapatite from FTIR data after immersion in SBF. X-ray diffraction analyses were done for all samples to identify the crystalline phases that were formed after immersion in SBF and also to determine the degree of crystallinity for each sample. Also, scanning electron microscopic (SEM) investigations were carried out to examine the morphological changes of the surfaces upon immersion and the effects of different individual fluoride additives. The solubility testing for glassy samples was performed and the changes in the pH of the leaching solution were measured and evaluated.The overall combined spectral and solubility data were compared to evaluate the suitability of the prepared glassy samples to be used as bone bonding materials.

Atrazine Molecular Imprinted Polymers: Comparative Analysis by Far-Infrared and Ultraviolet Induced Polymerization

Atrazine molecular imprinted polymers (MIPs) were comparatively synthesized using identical polymer formulation by far-infrared (FIR) radiation and ultraviolet (UV)-induced polymerization, respectively. Equilibrium binding experiments were carried out with the prepared MIPs; the results showed that MIPuv possessed specific binding to atrazine compared with their MIPFIR radiation counterparts. Scatchard plot’s of both MIPs indicated that the affinities of the binding sites in MIPs are heterogeneous and can be approximated by two dissociation-constants corresponding to the high-and low-affinity binding sites. Moreover, several common pesticides including atrazine, cyromazine, metamitron, simazine, ametryn, terbutryn were tested to determine their specificity, similar imprinting factor (IF) and different selectivity index (SI) for both MIPs. Physical characterization of the polymers revealed that the different polymerization methods led to slight differences in polymer structures and performance by scanning electron microscope (SEM), Fourier transform infrared absorption (FT-IR), and mercury analyzer (MA). Finally, both MIPs were used as selective sorbents for solid phase extraction (SPE) of atrazine from lake water, followed by high performance liquid chromatography (HPLC) analysis. Compared with commercial C18 SPE sorbent (86.4%–94.8%), higher recoveries of atrazine in spiked lake water were obtained in the range of 90.1%–97.1% and 94.4%–101.9%, for both MIPs, respectively.

IR and Raman Spectra Properties of Bi<sub>2</sub>O<sub>3</sub>-ZnO-B<sub>2</sub>O<sub>3</sub>-BaO Quaternary Glass System

Among new low-melting-point glasses, bismuth ate glass is deemed to have the most potential as an environmentally friendly replacement for polluting Pb-containing glasses. Current studies of boro-bismuthate glasses focus on the structural influence of the additional oxide in the context of low-melting-point electronic sealing applications. In this study, the structure of quaternary Bi2O3- ZnO-B2O3-BaO glasses was investigated spectroscopic ally, with Fourier-transform-infrared (FT-IR) and Raman spectra recorded for glasses with different main oxide contents. Signals in the FT-IR are mainly observed around 500 cm﹣1, 720 cm﹣1, 840 cm﹣1, 980 - 1080 cm﹣1, and 1200 - 1500 cm﹣1, while the Raman scattering peaks are located at 130 cm﹣1, 390 cm﹣1, 575 cm﹣1, 920 cm﹣1, and 1250 cm﹣1. The glasses are mainly structured around [BO3] units and the numbers of [BiO6] and [BiO3] units increase with the Bi2O3 content increasing. Concurrently, the FT-IR absorption peaks associated with [BO4] units shift to lower wave numbers, indicating a loosening of the glass structure. However, as the B2O3 content is increased, the numbers of [BO3] and [BO4] units increase, while those of [BiO3] and [BiO6] units decrease, highlighting a densification of the glass structure. ZnO acts as a network modifier in these glasses.

Hydroxyapatite and Collagen Combination-Coated Dental Implants Display Better Bone Formation in the Peri-Implant Area Than the Same Combination Plus Bone Morphogenetic Protein-2–Coated Implants, Hydroxyapatite Only Coated Implants, and Uncoated Implants

The objective of this study was to compare peri-implant bone formation among uncoated (UC), hydroxyapatite (HA), collagen plus HA (CH), and collagen, HA, plus bone morphogenetic protein-2 (BMP-2) implant groups. Implants in the UC group had acid-etched surfaces. The surface coating was applied using the aerosol deposition method. The coated surfaces were examined by scanning electron microscopy, x-ray diffraction (XRD), and Fourier-transformed infrared absorption analysis. Subsequently, 6 implants from each group (total, 24 implants) were installed in the tibias of rabbits. The animals were sacrificed at 6 weeks after implant installation. Peri-implant bone formation and bone-to-implant contact (BIC) were measured in histologic sections. Significant differences among groups were evaluated using analysis of variance. Based on the measured XRD patterns, there was a characteristic HA phase (International Centre for Diffraction Data [ICDD], 086-0740) coated on the titanium (ICDD, 089-3725). Subsequent coating processes for collagen and BMP-2 did not display additional diffraction peaks, but maintained the diffraction patterns of the HA-coated titanium. The presence of collagen was verified by infrared absorption analysis. When comparing these modifications with UC surfaces, only the CH coating displayed significantly greater peri-implant bone formation and BIC (P = .003 and P < .001, respectively). Adding BMP-2 to the implant surface did not produce any advantage compared with the CH coating. In this study, the CH group displayed significantly greater new bone formation and BIC than the other groups. There was no significant difference among the other groups.

Transesterification of Palm Oil Catalyzed by Fresh Water Bivalve Mollusk (Margaritifera falcata) Shell as Heterogeneous Catalyst

A heterogeneous catalyst has been derived from a waste material of fresh water bivalve mollusk (i.e., Margaritifera falcata outer shell) for the transesterification of palm oil. The shell was washed, crushed, ground, and calcined at 850 °C to derive active CaO catalyst. The catalyst was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), and differential thermal analysis/thermogravimetric (DT/TG) analysis. The DT/TG analysis showed the decomposition of calcium carbonate present in the shell at 780 °C. The XRD peaks for calcined shell were observed at 2θ = 32.22°, 53.53°, and 64.03° characteristics of CaO and showed high crystallinity. The textural structure of shell can be observed from the SEM images indicated that the structure of shell changed with calcination temperature. The FTIR absorption bands of the calcined shell were observed at 1471, 1090, and 874 cm–1, which are attributed...

A functional approach toward xerogel immobilization for encapsulation biocompatibility of Rhizobium toward biosensor

Sol-gel derived silica has tremendous applications as a biocompatible scaffold for the immobilization of cells. The use of xerogel as a matrix in the blueprint of biosensors is an appealing proposition due to several inimitable characteristics of xerogels, primarily because of their high porous nature, amendable pore size, and exceptionally large internal surface area. Morphological (X-Ray Diffraction and Thermogravimmetric Analysis) and optical (Fourier Transform Infrared and UV-Vis absorption) studies of the silica matrices with entrapped Rhizobial (Rz) structure of the biomaterial has been made. Temporal and concentration dependent studies were conducted for impregnated samples; it showed that the response time for the new biosensor for determining the concentration of Rz is less than 20 min. In this work, first time a novel avenue to create a generic approach for the fabrication of biosensor has been created.

Novel silicon surface passivation by porous silicon combined with an ultrathin Al2O3 film

We report on a dual passivation approach of monocrystalline-silicon (c-Si), which combines porous silicon (PS) treatment and pulsed laser deposition (PLD) of Al2O3 ultrathin layer. Al2O3 ultrathin films were deposited, under an oxygen background pressure of 10 mTorr. In this work we demonstrate that the dual treatment Al2O3/PS provide excellent passivation quality of c-Si surfaces. Surface passivation and reflectivity properties are investigated before and after heat treatment at 700 °C. The level of surface passivation is quantified using photoconductance and Fourier-transform infra-red absorption techniques. X-ray diffraction analysis suggested that the heat treatment leads to an average crystallite size decrease which help the diffusion of the Al2O3 NPs along the wafer surface. As a result, the effective minority carrier lifetime increases from 2 to 7 μs. Our results demonstrate that this dual treatment not only provides strong passivation of the c-Si substrate but decreases also the total surface reflectivity at 500 nm (from 28 % for untreated c-Si samples to ∼7 % for Al2O3/PS treated ones).

Effect of TiO2 doping and gamma ray irradiation on the properties of SrO–B2O3 glasses

Glasses from the binary strontium borate system of the basic composition 45%SrO–55%B2O3 together with samples containing different concentrations of TiO2 (2–10%) replacing equivalent SrO were prepared. The prepared samples were characterized by means of combined Fourier transform infrared absorption (FTIR) and UV-visible optical absorption spectroscopic measurements before and after subjecting the glasses to gamma irradiation with doses up to 8Mrad. XRD diffraction patterns have indicated the amorphous nature of the prepared glasses over the entire compositional range. Binary undoped strontium borate glass exhibits strong UV absorption bands which are attributed to the presence of unavoidable trace iron impurities (mainly Fe3+ ions) while the TiO2 containing glasses reveal an additional UV band which can be related to the presence of titanium ions mostly as tetravalent Ti4+ ions in this host strontium borate glass.FTIR spectra of the prepared glasses show the appearance of both triangular and tetrahedral borate units in their specific wavenumbers with the first groups in higher ratio. Minor changes have been identified in the intensity or position of the borate IR vibrational bands upon the increase of TiO2 within the glass content. The resolution of a distinct IR peak at 420cm−1 can be related to the presence of B―O or Ti―O―Ti bonding upon the increase of TiO2 content.

Control of composition and crystallinity in hydroxyapatite films deposited by electron cyclotron resonance plasma sputtering

Hydroxyapatite (HAp) films were deposited by electron cyclotron resonance plasma sputtering under a simultaneous flow of H2O vapor gas. Crystallization during sputter-deposition at elevated temperatures and solid-phase crystallization of amorphous films were compared in terms of film properties. When HAp films were deposited with Ar sputtering gas at temperatures above 460°C, CaO byproducts precipitated with HAp crystallites. Using Xe instead of Ar resolved the compositional problem, yielding a single HAp phase. Preferentially c-axis-oriented HAp films were obtained at substrate temperatures between 460 and 500°C and H2O pressures higher than 1×10−2Pa. The absorption signal of the asymmetric stretching mode of the PO43− unit (ν3) in the Fourier-transform infrared absorption (FT-IR) spectra was the narrowest for films as-crystallized during deposition with Xe, but widest for solid-phase crystallized films. While the symmetric stretching mode of PO43− (ν1) is theoretically IR-inactive, this signal emerged in the FT-IR spectra of solid-phase crystallized films, but was absent for as-crystallized films, indicating superior crystallinity for the latter. The Raman scattering signal corresponding to ν1 PO43− sensitively reflected this crystallinity. The surface hardness of as-crystallized films evaluated by a pencil hardness test was higher than that of solid-phase crystallized films.

Physical–chemical characterization of titanium dioxide layers sensitized with the natural dyes carmine and morin

The titanium dioxide (TiO2)-based layers sensitized with carmine and morin dyes were prepared using commercial P25 TiO2 powder as starting material. The influence of natural colorants as natural photosensitizers on TiO2 photoactivity was discussed from the point of view of UV–VIS and Fourier transform infra-red (FTIR) spectroscopy, fluorescence analysis, microscopy, X-ray diffraction and nitrogen adsorption-desorption isotherms determination. A shift to visible region of the sensitized TiO2 layers is observed. The decrease of sensitized TiO2 band gap improves its photoactivity in the visible domain. The fluorescence quenching of TiO2 sensitized with carmine is correlated with better adsorption of the dye molecules to the TiO2 surface and with electron injection process, also. The FTIR absorption spectra of samples proved the presence of dye molecules on TiO2 nanoparticles surface. Thus, the investigated sensitized TiO2-based layers could have potential in photoelectrochemical applications.

Influence of Substituent Type and Position on the Adsorption Mechanism of Phenylboronic Acids: Infrared, Raman, and Surface-Enhanced Raman Spectroscopy Studies

This paper shows systematic spectroscopic studies using Fourier-transform infrared absorption (FT-IR), Fourier-transform Raman (FT-Raman), and surface-enhanced Raman (SERS) in an aqueous silver sol of fluoro and formyl analogues of phenylboronic acids: 2-fluorophenylboronic acid (2-F-PhB(OH)2), 3-fluorophenylboronic acid (3-F-PhB(OH)2), 4-fluorophenylboronic acid (4-F-PhB(OH)2), 2-formylphenylboronic acid (2-CHO-PhB(OH)2), 3-formylphenylboronic acid (3-CHO-PhB(OH)2), and 4-formylphenylboronic acid (4-CHO-PhB(OH)2). To produce an extensive table of vibrational spectra, density functional theory (DFT) calculations with the B3LYP method at the 6-311++G(d,p) level of theory were performed for the ground state geometry of the most stable species, dimers in cis-trans conformation. On the basis of the SERS spectral profile, the adsorption modes of the phenylboronic acid isomers were proposed. The type of substituent and its position in the phenyl ring have a strong influence on the geometry of isomers on the silver nanoparticle's surface. This effect was especially evident in the case of 4-CH-PhB(OH)2, for which dearomatization of the phenyl ring took place upon adsorption.

Magnetic dilution effect of nano-crystalline NiFe2O4 synthesized via sucrose-assisted combustion route

Sucrose assisted combustion route was utilized to synthesize nano-crystalline Cr-substituted nickel ferrites, NiFe2−xCrxO4 (x=0.0–1.0). The synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) techniques to investigate the effect of Cr-substitution on the structural and magnetic properties of the entire system. Single-phase formation was checked using XRD and a proper cation distribution was estimated depending on the related structural parameters. FT-IR absorption bands were found to be in the expected range, which fortifies the spinel formation. The change in the structural properties by the addition of Cr3+ ions was discussed from the view point of ionic radii of the entire ions. TEM revealed the agglomeration nature of the synthesized powders. The magnetic properties were strongly affected by Cr-substitution. The decrease in the saturation magnetization and coercivity with increasing Cr-content was attributed to magnetic moments and magneto-crystalline anisotropy of the entire ions, respectively.