Electron Spectroscopy For Chemical Analysis Spectra Research Articles

Ca2+ - substitution effect on the electronic structure of CaCu3Ti4O12 studied by electron spectroscopy for chemical analysis

A detailed electronic structure study of quadruple perovskite series, Ca1+xCu3-xTi4O12 (for x = 0.0, 0.1, 0.2, 0.5, 1.0), using electron spectroscopy for chemical analysis (ESCA) has been carriedout. The Ti2p ESCA spectra imply that Ti ions remain in the tetravalent state and show the presence of Ti clusters, TiO6 and TiO5. The Cu2p spectra indicate the dominance of the divalent state of Cu ions. The Ca2p spectra show that Ca atoms are divalent but spectral features are suggestive of the presence of Ca superficial atoms in the system which is possibly due to the precipitation of Ca atoms in the grain boundary regions. The Ca2p in conjunction with O1s spectra shows that there is a strong possibility of hybridization of Ca2p states with the O1s and/or the Cu3d orbitals. The remarkable shift in O1s spectra towards the lower energy side for the samples with x ≥ 0.5 is mainly due to the substitution of large cation Ca2+ (1.0 Å), for small cation Cu2+ (0.73 Å) in the series. That results in bond length enhancement and weakening of the bond strength. It is proposed that the shift of O1s peaks can also be partially caused by oxygen vacancies; nevertheless, more experiments are required to substantiate this.

ESCA and TOF‐SIMS Study on Oxidised and Reduced Polypyrrole‐Poly(Vinylsulfonic Acid, Sodium Salt) Films Synthesized on Ti Electrodes

We had previously reported on a surface analysis investigation of electrochemically synthesized, both oxidized and reduced, polypyrrole‐poly‐4‐styrenesulfonate free‐standing films (Sin et al., 2000). We apply the same techniques that we used earlier (Sin et al., 2000) to study polypyrrole‐poly(vinylsulfonic acid, sodium salt) (PPy‐PVS) free‐standing films. Electron Spectroscopy for Chemical Analysis (ESCA) and Time of Flight Secondary Ion Mass Spectrometry (TOF‐SIMS) were used in the surface morphology study of oxidized and reduced PPy‐PVS composite films. ESCA spectra seem to indicate that the CO and C–OH structures reduced to C–C bonds during the reduction process and also seem to reveal interesting charge transfer behavior, namely. NH+ and N–H bonds to imine group (N=C) at reduced PPy‐PVS free standing films. Furthermore, TOF‐SIMS ion mapping also provided some interesting surface distribution of elements on PPy‐PVS composite films. A comparison of surface conductivities between the two sides of both types of films was made,with conductivity measurements being carried out using the four‐point probe technique.

Effect of PET Melt Spinning on TiO2 Nanoparticle Aggregation and Friction Behavior of Fiber Surface

Poly(ethylene terephthalate) (PET) was incorporated with different amounts of TiO2 nanoparticle and then spun into fibers of different diameters. Surface properties of these modified fibers were investigated by friction force, scanning electron microscopy, energy dispersive X-ray analysis, and electron spectroscopy for chemical analysis (ESCA). TiO2 nanoparticles showed aggregation on the fiber surface. The number of aggregates increased as the amount of TiO2 nanoparticle increased and/or the diameter of spun fiber decreased. These were evidenced from SEM and also from an increased C(1s)/O(1s) ratio in the ESCA spectra. The aggregates of TiO2 nanoparticle on the fiber surface cause unevenness, leading to a decreased friction-contact area between surface of the sliding fiber and its encountered surface. Thus, the friction force that arose from the interface reduced. In addition, on the basis of different amounts of TiO2, a broad range of fiber frictions could be formed. This would provide promise to potent...

Photo polymerization of acrylamide onto calcium carbonate particle surfaces and filled nylon‐6

AbstractThe polymerization of acrylamide (AAM) onto calcium carbonate (CaCO3) particle surfaces induced by ultraviolet light and the properties of polyamide‐6 (PA6) filled with the surface‐treated CaCO3 were studied. Electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM), particle size distribution, impact strength and degree of polymerization measurements were determined. After AAM polymerization, a PAAM layer was formed on the CaCO3 surface. This layer tightly banded the CaCO3 particle and could not be washed away by acetone. A N1s peak was observed in the ESCA spectra of the treated CaCO3 particles. The average particle size of the treated CaCO3 increased compared to that of the original CaCO3. The interfacial interaction and impact strength of the treated CaCO3–filled PA6 were enhanced compared to those of the untreated CaCO3–filled PA6. Polym. Eng. Sci. 44:1277–1282, 2004. © 2004 Society of Plastics Engineers.

Formation of carbon-gold-sulfide conductive granular molecules by a cooperation process of plasma CVD and sputtering

Carbon-gold-sulfide (C-Au-S) films formed by cooperation process of plasma chemical vapor deposition (CVD) and sputtering were studied by x-ray diffraction, electron spectroscopy for chemical analysis (ESCA) and refractive index measurement before and after thermal treatment at $200\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ for 30 min. The x-ray diffraction patterns of gold cluster in the film were not observed. The chemical shifts of ESCA spectra for C, Au, and S atoms were 2.90, 2.40, and 0.95 eV, respectively, and were changed little after the thermal treatment. The atoms are expected to be ionic-bonded to the granular molecule. The refractive index was changed little by the thermal treatment compared to the carbon-gold (C-Au) film. The thermally stable conductive granular molecule of C-Au-S was confirmed experimentally.

Stability of radiopaque iodine-containing biomaterials

Stability tests have been performed on two typical iodine-containing radiopaque poly(methacrylate) copolymers. Material A is a terpolymer of methylmethacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA) and 2-[4-iodobenzoyl]-oxo-ethylmethacrylate (4-IEMA); material B is a copolymer of MMA and 4-IEMA. Cylindrical specimens of material A were implanted subcutaneously and intraperitoneally in Wistar rats. The implants were retrieved after 2 years. Histology showed that the material was well-tolerated. Detailed analysis of the surface of the implants by electron spectroscopy for chemical analysis (ESCA) revealed that the material remained stable. No differences could be detected between the ESCA spectra of the explants, and those of the control specimens, which were from the same synthetic batch and which were stored in dry form during the entire experimental period. Material B was also stable upon irradiation with X-rays in vitro, even at high doses, compared to the clinical situation. Exposure of material B to γ-radiation, however, was found to lead to structural degradation. This was evident from clear yellowing, and also from the ESCA spectra. The spectra revealed that material B deteriorates during γ-irradiation through rupture of C–C and/or C–O chemical bonds, not via C–I bond disruption. It can be concluded that iodine is tightly bound to these radiopaque biomaterials. This is important with regard to potential applications of these materials as implant biomaterials.

ENDOTHELIALIZATION OF OXYGENATOR MEMBRANES THROUGH GLOW DISCHARGE SURFACE TREATMENT

Purpose Thrombosis remains problematic for the use and development of extracorporeal membrane oxygenators. Blood-surface interactions such as platelet deposition and plasma weeping reduce the device effectiveness and patient support period. This study aims to investigate the potential to encourage endothelial cell (EC) attachment and growth on clinically utilized microporous hollow fibers (MHFs), as a step towards the development of an endothelialized artificial lung. Methods Fiber Surface Modification & EC Seeding: Polypropylene MHFs and siloxane-coated MHFs were modified using radio frequency glow discharge (RFGD). Ammonia gas was used as the reaction substrate as a means of attaching amine groups to MHF surfaces. Surface modification was verified by water contact angle and electron spectroscopy for chemical analysis (ESCA) (NESAC/BIO, Seattle, WA). Modified samples were incubated in aqueous solutions of the adhesion protein, fibronectin (Sigma-Aldrich, St. Louis, MO) for 30 min before seeding. Samples were then seeded on the inner walls of conical tubes containing 4.2±104 cells/ml and incubated on rollers for 24 hrs. Confluence & Growth Curve Evaluation: After EC seeding, samples were cultured in multi-well plates. Cell viability was evaluated with a mitochondrial assay (MTT) during a six day growth period. Micrographs were taken of MHF surfaces, and the absorbance levels of the MTT solutions, corresponding to cell viability, were read. Results ESCA spectra revealed decreased carbon and increased oxygen and nitrogen surface concentrations in RFGD modified samples. Modification was further demonstrated by decreased water contact angle. Micrographs and mitochondrial assay results showed that RFGD + fibronectin treated samples reached confluence within the 6 day growth period and exhibited improved adhesion and growth relative to untreated samples. Conclusion Surface characterization and EC adhesion and growth data indicate the feasibility of improving the cell culture potential for MHFs. Such modified and cultured fibers may be less prone to adverse surface-blood interactions and provide the biocompatible surface necessary for a chronic artificial lung.

ESCA and TOF-SIMS study on oxidised and reduced polypyrrole-poly(4-styrenesulfonate) free-standing films synthesized on Ti electrodes

Thin films of polypyrrole, composited with poly(4-styrenesulfonate), formed electrochemically on titanium plate electrodes could be peeled off readily as free standing films, before and after reduction in the aqueous forming solution. Both surfaces (electrolyte side and electrode side) of such free standing films had been investigated using electron spectroscopy for chemical analysis (ESCA) and time of flight secondary ion mass spectrometry (TOF-SIMS). The morphologies for the electrolyte sides of both oxidized and reduced forms of such polypyrrole composite films were clearly different from those of the electrode sides, but little difference in surface conductivity between the two sides of each form was detectable using the four-point probe technique. ESCA spectra showed high sodium ion presence on the surfaces of the reduced form but not detectable on the surfaces of the oxidized form. Secondary electron images and ion maps of sampled areas on the films from the TOF-SIMS study revealed some interesting surface features.

Structure and morphology of isotactic polypropylene functionalized by electron beam irradiation

The structure and morphology of isotactic polypropylene (iPP), functionalized by electron beam irradiation at room temperature in air, are investigated by elementary analysis, FT-infrared (FTIR) spectroscopy, electron spectroscopy for chemical analysis (ESCA), polariscope, and static contact angle. Elementary analysis reveals that the element oxygen has been introduced onto iPP chains after electron beam irradiation. In addition, as shown from FTIR spectra, oxygen-containing groups, such as carbonyl, carboxyl, and ether groups, are introduced onto iPP molecular chains. The dependence of oxygenation extent (as measured by O1S/C1S value of ESCA spectra) on electron beam dose is obtained. Under polariscope, it can be observed that the dominant alpha phase appears to become more enhanced, and there is no crystalline phase transition. The static contact angle of iPP decreases with increasing dose. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 75–82, 2000

Structure and morphology of isotactic polypropylene functionalized by electron beam irradiation

The structure and morphology of isotactic polypropylene (iPP), functionalized by electron beam irradiation at room temperature in air, are investigated by elementary analysis, FT-infrared (FTIR) spectroscopy, electron spectroscopy for chemical analysis (ESCA), polariscope, and static contact angle. Elementary analysis reveals that the element oxygen has been introduced onto iPP chains after electron beam irradiation. In addition, as shown from FTIR spectra, oxygen-containing groups, such as carbonyl, carboxyl, and ether groups, are introduced onto iPP molecular chains. The dependence of oxygenation extent (as measured by O1S/C1S value of ESCA spectra) on electron beam dose is obtained. Under polariscope, it can be observed that the dominant alpha phase appears to become more enhanced, and there is no crystalline phase transition. The static contact angle of iPP decreases with increasing dose. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 75–82, 2000

Optimization of commercial zirconic acid based pretreatment on hot-dip galvanized and Galfan coated steel

Abstract The influence of a commercial zirconic acid based pretreatment has been investigated on hot-dip galvanized and Galfan coated steel. The studied pretreatment system includes two alkaline cleaning steps, an alkaline oxidation and a zirconic acid based after rinse. The optimum conditions for the after rinse were tested by varying the rinse parameters such as treatment time, temperature, solution concentration and pre- and postdrying of panels. The pretreated panels were characterized by using electron spectroscopy for chemical analysis (ESCA), glow discharge optical emission spectroscopy (GD-OES) and contact angle measurements. Pretreated panels were also clear coated and corrosion resistance of the coated panels was tested. The results show that, for the two lowest solution concentrations, time and temperature are the most important treatment parameters. They affect the amount of zirconium adsorbed in the conversion coating, but are less important for the highest solution concentration. The highest level of zirconium on the samples is obtained with the intermediate concentration, in combination with the longest treatment time and highest temperature. According to peak positions in the ESCA spectra, the Zr adsorbed is mainly in the form of ZrO2. GD-OES depth profiles show that the zirconic acid based pretreatment has reacted to different depths in the studied zinc coated steel strip materials. The trend in the corrosion resistance is similar for both substrates. According to contact angle measurements the initial pretreated surface is wetting and hydrophilic in nature. The pretreated surface was also found to age rapidly.

Surface chemical interaction of fibrous asbestos with biocells: An ESCA study

High-resolution X-ray Photoelectron Spectroscopy (XPS), also known as ESCA (Electron Spectroscopy for Chemical Analysis), has been used to monitor the surface chemistry of silicate minerals exposed to living cells. We have followed the chemical changes in the silicates induced by changes in elemental composition (reflected in the Si Al and Si Mg ratios) and structure. Changes in bond strength which occur in the process were monitored via the line shifts in the ESCA spectra. As it is likely that differences in surface chemistry affect the interactions of silicates with cellular systems, we have embarked on a systematic study of well-characterized silicates exposed to murine tumour Ehrlich cells under controlled conditions. ESCA identifies changes in the surface chemistry of asbestos caused by interactions with cells, while atomic absorption spectrometry (AAS) monitors silicate-induced changes in the cell iron content. There is a significant increase in iron concentration in the cells and in the Si Mg ratio on the surface of asbestos after contact with the cells. The complex C(1s) and Si(2p) ESCA spectral features and the presence of trace elements in freeze-dried cell-asbestos mixtures indicate the presence of chemical interactions of asbestos with the cells. We believe that such studies may eventually help in the identification of pathogenic mechanisms involving mineral dusts.

Soft chemical synthesis and characterization of lithium nickel oxide electrode materials

Soft chemistry was used to prepare ordered nanophase Li0.6NiO2 electrode materials by completing the oxidation of Ni2+ to Ni3+ and/or Ni4+ species with H2O2 oxidant during solution reactions at 50–60 °C and evaporation at 105–150 °C rather than during sintering. Both elemental analysis and electron spectroscopy for chemical analysis (ESCA) results indicate that oxidation was completed. The deconvoluted ESCA spectra of nickel ions exhibited a semi-quantitative ratio of Ni4+∶Ni3+=60∶40 which presented no significant change with increase of sintering time. After sintering for up to 11 h at 700°C, ordered Li0.61Ni0.96O2.0 ceramics were formed (R3m, a0=0.2837 nm, c0=1.417 nm). Distribution of the crystallite size was in the range of 80–200 nm. As sintering times were increased, the crystallite shapes exhibited a more distinct morphology, and the ordering degree of the cations was enhanced, while the conductivity was sharply enhanced up to 2.0×10−1 Ω−1 cm−1 at 30 °C. Compared to conventional ceramic and solution methods, the ordered nanophase Li0.61 Ni0.96O2.0 ceramics was obtained at 700 °C with shorter sintering times (≈ 11 h).

Surface modification of polyolefine by UV light/ozone treatment

The surface modification of polyethylene (PE) and polypropylene (PP) was investigated by UV light/ozone (UVO) treatment. The surface oxygenation was determined by electron spectroscopy for chemical analysis (ESCA). As shown from ESCA spectra, after UVO treatment, oxygen-containing functional groups, such as carbonyl, carboxyl, and ether groups, were produced in the sample surface. The dependence of oxygenation extent (as measured by O1s/C1s value of ESCA spectra) on different experimental conditions, such as irradiation time, temperature, and O2 flow rate, was obtained. It was shown that after UVO treatment at suitable conditions the surface properties of polyolefine samples, such as hydrophilicity, adhesion property, and dyeability, were improved remarkably. Furthermore, UVO treatment in short time does not have notable effect on the ageing property. It was concluded that UVO treatment is a promising technique to modify polyolefine surface properties. © 1996 John Wiley & Sons, Inc.

ESCAによるSiO<SUB>2</SUB>/Si内の電子トラップ，正孔トラップの検出

Since very small amounts of defects or impurities influence Si MOS (Metal-Oxide-Semiconductor) device characteristics, it is usually difficult to detect them in the SiO2/Si structures used for these devices by ordinary surface characterization. We therefore tried to resolve this problem with a different approach. In an effort to detect electron and hole traps in SiO2/Si samples, the electric current that flows from the sample to the ground was measured as a function of the X-ray irradiation time during ESCA (Electron Spectroscopy for Chemical Analysis) measurements. The transient of this current was found to be due to electric charges supplied to the Si side of the SiO2/Si interface. The number of these charges increases as the electric charges of the opposite sign become trapped at oxide traps in the SiO2. This transient was found to be the sum of the exponential functions of the X-ray irradiation time with different time constants. Various types of traps can be distinguished by these time constants and the sign of the current. Our first experiment showed that traps whose concentration is of the order of 1014 m−2 can be detected by this method, whereas they cannot be easily detected with such sensitivity in an ESCA spectra because the ESCA detection limit is of the order of 1016 m−2. This new method was used to compare two different kinds of thermally oxidized silicon, namely, that oxidized in O2/N2 and that oxidized in pyrogenic steam. The present method is expected to be useful in the process development of MOS devices using ultra-thin SiO2 films.

Controlled modification of poly(hydroxybutyrate) surfaces by a perfluorohexane plasma: ESCA and contact angle studies

AbstractPoly(hydroxybutyrate) films and inorganic glass slides were treated by cold plasma. The composition of the gas mixture of perfluorohexane and hydrogen was varied to obtain controlled surface coatings of different hydrophobicities. The analysis by weight variation, scanning electron microscopy (SEM), electron spectroscopy for chemical analysis (ESCA), and contact angle measurements were used to evaluate the influence of the flow rate, composition, and the plasma power on the surface structure after the plasma deposition. High‐resolution ESCA spectra were used to determine quantitatively the amount of different fluorine‐containing species present in the plasma‐deposited layers. Molecular structures and surface energies of deposited layers on polymer substrates were compared with those on inorganic substrates. In both cases a strong correlation was found between the surface free energy and the fluorine/carbon ratio as well as the oxygen/carbon ratio. Furthermore, samples with high carbon/fluorine ratios showed a high content of CF2 and CF3 groups. © 1993 John Wiley & Sons, Inc.

Experimental Evidence for Anion Selective Behavior of Ion Beam Sputtered Film of Alkali Metal‐Free Phosphate Glass Deposited on MOS‐Diode

Selective adsorption of an anionic species on an alkali metal‐free lead phosphate glass membrane on a metal oxide semiconductor (MOS) diode was studied using capacitance‐voltage curves and electron spectroscopy for chemical analysis (ESCA) measurements. The phosphate glass‐coated MOS diode shows a linear relationship between the anion concentration and the relative capacitance change. The oxygen binding energy in the phosphate glass as determined by ESCA spectra shows two types of peaks 23.85 and 26.56 eV. It can be concluded that the anionic species can adsorb preferably on the lower surface anionic site and that the anion selective characteristics originate from the MOS diode surface.

Kalman filter quantitative resolution of shifted ESCA spectra after optimal alignment by simulated annealing

The quantitative separation of overlapped responses accomplished by the Kalman filter algorithm is deteriorated by the errors in the model due to shifts of the component peaks. This is particularly true for spectral resolution in Electron Spectroscopy for Chemical Analysis (ESCA). A computational approach for the quantitative resolution of overlapping ESCA spectra when there is loss of collinearity between the pure component peaks and the mixture peak, has been developed. The procedure makes itera tive use of the Kalman filter for resolving the mixture spectrum with the component spectra aligned according to some values of the position parameters, and of the simulated annealing algorithm to find the optimal alignment. The performance of simulated annealing in pursuing this task, has been compared with those of simplex and steepest descent, by analyzing a set of overlapped synthetic spectra and some ESCA spectra of powder mixtures of lead compounds.

Structural changes in rubber during milling

AbstractProcessing operations such as milling, change the chemical structure of rubber. Infrared (IR) spectroscopy and electron spectroscopy for chemical analysis (ESCA) have been used to detect the formation of functional groups during the milling of natural rubber (NR), epoxidised natural rubber (ENR), styrene butadiene rubber (SBR), neoprene (CR), and acrylic rubber (AR). The concentration of carbonyl () groups as detected by IR spectroscopy increases with the time of milling for all the rubbers. The concentration of hydroxyl groups (OH) in NR and ENR also increases during milling. ESCA spectra of the rubbers before and after milling reveal that the peaks are broader for milled rubber, and that the concentration of oxygen is also greater. In the case of ENR, however, the concentration of epoxide rings decreases and that of furan rings increases with the time of milling.

Investigation of the Surfaces of Fluorine Contatining Acrylic Polymers by Critical Surface Tension of Wetting(.GAMMA.c) and ESCA.

Surfaces of poly (fluoroalkyl methacrylate)s and poly (fluoroalkyl α-fluoroacrylate) s were investigated by measuring critical surface tension of wetting (γc). Thin layers of polymer films were obtained by the solvent casting method. The concentration of fluorine in the films was determind by Electron Spectroscopy for Chemical Analysis (ESCA). We observed a good relationship between the concentration of fluorine determined by ESCA spectra and γc of the thin polymer film.i. e., the more of the F1s ESCA signal, the less γc of the polymer film. It was concluded that the structure of either main chain and side chain fluoroalkyl group or the alkyl chain length of polymers affect the values of γc of the polymer films.