XPS analyses

XPS analysis was carried out on the TFC-S membranes with a calcite deposit, calcium-humate floes, and on clean membranes, calcium-humate precipitates, and pure HA. No calcium was found on the clean membrane. The identification of peaks is difficult, due to the complexity of the structure of humic acid and the similarity to the membrane (carboxylic groups). Jucker and Clark (1994) suggested the presence of a Ca-humic bond in their measurements at 349.8 eV. This result was confirmed with the calcium-humate complex sample of this study (349.6 eV). On the membranes the chemical shift is different, possibly indicating the presence of a calcite precipitate (346.7 eV) and a calcium-humate complex, but the peaks cannot be resolved due to the small amount of calcium present. 

---

Sensitive materials, such as metal salts or organometallic compounds, may decompose during XPS analysis, particularly when a standard x-ray source is used. Apart from the x-rays themselves, heat and electrons from the source may cause damage to the samples. In such cases, a monoclnomated x-ray source can offer a... 

This approach is the most useful for routine quantitative xps analysis. 

A principal disadvantage of conventional XPS was lack of spatial resolution the spectral information came from an analyzed area of several square millimeters and was, therefore, an average of the compositional and chemical analysis of that area. Many technological samples are, on the other hand, inhomogeneous on a scale much smaller than that of conventional XPS analysis, and obtaining chemical information on the same scale as the inhomogeneities would be very desirable. 

Step 3. The set of fracture properties G(t) are related to the interfaee structure H(t) through suitable deformation mechanisms deduced from the micromechanics of fracture. This is the most difficult part of the problem but the analysis of the fracture process in situ can lead to valuable information on the microscopic deformation mechanisms. SEM, optical and XPS analysis of the fractured interface usually determine the mode of fracture (cohesive, adhesive or mixed) and details of the fracture micromechanics. However, considerable modeling may be required with entanglement and chain fracture mechanisms to realize useful solutions since most of the important events occur within the deformation zone before new fracture surfaces are created. We then obtain a solution to the problem. 

Ge(IV). The observation of Ge(IV) in the XPS analysis is most probably the result of chemical attack by ambient oxygen. Such an attack has also been reported for Ge on Au made by Physical Vapor Deposition [68]. 

The surface analyses of the Co/MgO catalyst for the steam reforming of naphthalene as a model compound of biomass tar were performed by TEM-EDS and XPS measurements. From TEM-EDS analysis, it was found that Co was supported on MgO not as particles but covering its surface in the case of 12 wt.% Co/MgO calcined at 873 K followed by reduction. XPS analysis results showed the existence of cobalt oxide on reduced catalyst, indicating that the reduction of Co/MgO by H2 was incomplete. In the steam reforming of naphthalene, film-like carbon and pyrolytic carbon were found to be deposited on the surface of catalyst by means of TPO and TEM-EDS analyses. 

The electrochemical behavior of single-crystal (100) lead telluride, PbTe, has been studied in acetate buffer pH 4.9 or HCIO4 (pH 1.1) and KOH (pH 12.9) solutions by potentiodynamic techniques with an RRDE setup and compared to the properties of pure Pb and Te [203]. Preferential oxidation, reduction, growth, and dissolution processes were investigated. The composition of surface products was examined by XPS analysis. It was concluded that the use of electrochemical processes on PbTe for forming well-passivating or insulating surface layers is rather limited. 

XPS Analysis. The ultrahigh vacuum (OHV) catalyst treatment-surface analysis system employed to characterize and treat the cobalt catalysts has been described previously ( 1, 2 The catalyst treatment and data analysis procedures have also been described (JJ. Briefly, the samples were treated in quartz reactors and then transferred under UHV into a modified Hewlett-Packard 5950A BSCA spectrometer for emalysis. Peak areas were normalized with theoretical cross-sections (Z) to obtain relative atomic compositions. 

PtRu nanoparticles can be prepared by w/o reverse micro-emulsions of water/Triton X-lOO/propanol-2/cyclo-hexane [105]. The bimetallic nanoparticles were characterized by XPS and other techniques. The XPS analysis revealed the presence of Pt and Ru metal as well as some oxide of ruthenium. Hills et al. [169] studied preparation of Pt/Ru bimetallic nanoparticles via a seeded reductive condensation of one metal precursor onto pre-supported nanoparticles of a second metal. XPS and other analytical data indicated that the preparation method provided fully alloyed bimetallic nanoparticles instead of core/shell structure. AgAu and AuCu bimetallic nanoparticles of various compositions with diameters ca. 3 nm, prepared in chloroform, exhibited characteristic XPS spectra of alloy structures [84]. 

EQCM Analyses It was suggested by XPS analysis that the nonprecious metals were leached out from the alloy surface during CVs in acidic electrolyte solution. Therefore, we used an EQCM to measure the mass change at the electrode. The resolution and stability of our 10 MHz EQCM was +0.1 Hz, i.e., +0.44ngcm without any signal averaging. 

X-ray photoelectron spectroscopy is frequently applied in the fields of catalysis and polymer technology. It has poor spatial resolution, and is generally limited to homogenous samples. Radiation sensitive materials are more appropriate for XPS analysis, as the X-ray beam is less damaging to the specimen surface than the electron beam used in AES, partly due to the lower flux densities that are used. 

The corrosion of stainless steel in 0.1 mol-1 NaCl solutions at open circuit potential was studied in detail by Bruesch et al. [106] using XPS in combination with a controlled sample transfer system [38]. It was verified by XPS analysis that the passivating film contains chromium oxide. The position and the height of the Cr concentration maximum depends critically on the bulk chromium content of the steel. Significant variations in the electrode passivation properties were observed at a Cr concentration of 12%, while the film behaviour was found to be rather independent of the other components like Mo, Ni, Cu. From the fact that the film structures and... 

For the amounts of Fe below x=l, the sheath-like structures form mostly (Fig. 2d). This proceeds likely so when the Fe amount is low enough, the catalyst does not get to deeper layers of onions and pyrrole polymerises already in outer layers, which hinders the access of further monomer molecules to the onions inside. Use of still smaller amounts of the Fe catalyst results in formation of carbon (e.g., OCM-.NO.25) consisting of both foam- and sheath-like structures (Fig. 2c). The XPS analysis reveals that 0.43 wt.% Si and 0.5 wt.% Fe remain in the surface layer of OCM-.NO.25. This sample as well as CMK-3N1.25 and CMK-3N2.00 do not bum up totally (Table 1, Fig. 3). 

---