Samples X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy (XPS), also called electron spectroscopy for chemical analysis (ESCA), is described in section Bl.25,2.1. The most connnonly employed x-rays are the Mg Ka (1253.6 eV) and the A1 Ka (1486.6 eV) lines, which are produced from a standard x-ray tube. Peaks are seen in XPS spectra that correspond to the bound core-level electrons in the material. The intensity of each peak is proportional to the abundance of the emitting atoms in the near-surface region, while the precise binding energy of each peak depends on the chemical oxidation state and local enviromnent of the emitting atoms. The Perkin-Elmer XPS handbook contains sample spectra of each element and bindmg energies for certain compounds [58]. 

A catalyst supported on y-AFO was prepared from Re2Pt(CO)i2l (Fig. 70) and characterized by IR. X-ray photoelectron spectroscopy (XPS), and TPR. The chemi.sorbed cluster was treated with H2 at about 150 C resulting in fragmentation and formation of rhenium subcarbonyls at 400 C the sample was completely decarbonylated. A catalyst prepared from a mixture of Re3(//-H)3(CO)i2l and PtMe2(// -cod)] and treated under equivalent conditions showed the rhenium to... 

Suhtnicion nickel powders luive been synthesized successfully from aqueous NiCh at various tempmatuTKi and times with ethanol-water solvent by using the conventional and ultrasonic chemical reduction method. The reductive condition was prepared by flie dissolution of hydrazine hydrate into basic solution. The samples synthesized in various conditions weae claractsiz by the m ins of an X-ray diffractometry (XRD), a scanning electron microscopy (SEM), a thermo-gravimetry (TG) and an X-ray photoelectron spectroscopy (XPS). It was found that the samples obtained by the ultrasonic method were more smoothly spherical in shape, smaller in size and narrower in particle size distribution, compared to the conventional one. 

Lewera A, Inukai J, Zhou WP, Cao D, Duong HT, Alonso-Vante N, Wieckowski A (2007) Chalcogenide oxygen reduction reaction catalysis X-ray photoelectron spectroscopy with Ru, Ru/Se and Ru/S samples emersed from aqueous media. Electrochim Acta 52 5759-5765... 

X-ray Photoelectron Spectroscopy analysis of the samples was performed with a Surface Science Instruments spectrometer (SSI 100) with a resolution (FWHM Au 4f7/2) of 1.0 eV. The X-ray beam was a monochromatised AlKa radiation (1486.6 eV). A charge neutraliser (flood gun) was adjusted at an energy of 6 eV. As the Cls spectra of these compounds were very complex, the binding energies were referenced to the binding energy of Ols, considered experimentally to be at 531.8 eV [8). 

For probing the nature of the acid sites by X-ray photoelectron spectroscopy (XFS), the samples were evacuated before gaseous pyridine was adsorbed. Excess pyridine was desorbed at 1S0°C, and then samples were pressed onto a sample stub imder Nj and loaded into the SCIENTA ESCA-300 instrument without exposure to air. Sample charging was minimized by using a Qood gun while acquiring the experimental data. 

X-ray photoelectron spectroscopy (XPS) is based on the photoelectric effect. When a sample is irradiated with monochromatic X-rays, such as the K lines of Mg (1253.6eV) or Al (1486.6 eV), core-level electrons from the inner shells of atoms in the sample will be ejected from the sample to the surrounding vacuum. The kinetic energy, Er, of the emitted photoelectron is given by... 

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. 

Figure 10.15. X-ray photoelectron spectroscopy measurements on prereduced Pd/LaCo03 into Pd0/CoO c/La2O3 after successive exposures under reaction conditions 0.15vol.% NO, 0.5vol.% H2 and 3 vol.% 02. Photopeaks Pd 3d and N Is recorded on the calcined sample in air at 400°C (a) after reduction in H2 at 500°C (b) after exposure under reaction conditions at 25°C (c) at 200°C for 30 min (d) at 300°C for 30 min (e) at 300°C for 2h (f) at 500°C for 30min (g) and at 500°C for 2h (h) (reproduced with permission from Ref. [117]).

A part, consisting of a carbon fiber composite tube, was initially adhered to the inside of a short titanium coupling by a silica-filled epoxy. The bond failed and a fluorinated mold release was believed to be the cause of the failure and was the purpose for this investigation. A sample of the epoxy (Sample A) and the part (Sample B) were submitted for X-ray photoelectron spectroscopy (XPS) to analyze for the presence of both fluorine and silicon. 

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