Photoelectron Spectroscopy XPS, ESCA

A more typical set of XPS data taken with a laboratory-based instrument is shown in Fig. 7. Since there are only a limited number of suitable sources (the line width is important since it impacts the resolution achievable in the photoelectron spectrum and whether a particular chemical shift can be detected) in a laboratory setting, the depth resolution cannot be tuned continuously. The most common sources derive themselves from the A1 Ka line at 1486.7eV and the Mg Ko line at 1253.6 eV. Often, a combination of both of these anodes is found in a laboratory X-ray source 

---

X-ray photoelectron spectroscopy (XPS-ESCA) was used to analyse the chemical state of the catalyst surface. Two different activation temperatures were conpared, 400 (sanq)le 1) and 170°C (sample 2) for 1 hour under hydrogen flow. The san jles were investigated closer within the energy domain where Ni appears in the spectra (855-862 eV). Two peaks indicate nickel NiO and metallic Ni and that the NiO peak is much smaller for sanple 1 than for sanqrle 2. 

X-ray photoelectron spectroscopy (XPS, ESCA) in rapidly frozen solutions... 

X-ray photoelectron spectroscopy XPS (ESCA) Photon 1253.6 eV (MgKa) 1486.6 eV (AlKa)... 

Table 17.15 shows results obtained from the application of various bulk and surface analysis methods to lithium metal at rest or after cyclization experiments, as well as at noble metal and carbon electrodes after cathodic polarization. Several surface and elemental analysis methods are applied, including X-ray photoelectron spectroscopy (XPS, ESCA/XPS), energy dispersive analysis of X-rays (X-ray microanalysis, EDAX), Eourier transform infrared spectroscopy (ETIR), Auger electron spectroscopy (AES), ellipsometry (E), electro-modulated infrared reflectance spectroscopy (EMIRS), double modulation Fourier transform infrared spectroscopy (DMFTIR), subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS), gas chromatography (GC), IR spectroscopy. X-ray diffraction (XRD), and atomic force microscopy (AFM). 

In-line, continuous applications of atmospheric plasma technology are most prevalent in the surface cleaning of roll-to-roll foils. Specifically, the effects of oxygen plasma treatments on the composition and wettability of cold-rolled aluminum foil surfaces, for example, have been closely examined using measurements by X-ray photoelectron spectroscopy (XPS/ESCA) and contact angle. Common cleaning results indicate that oxygen plasma treatments will contribute two primary surface effects on the composition of cold-rolled aluminum. The first is the efficient removal of residual carbon particles. The second is an increase in the thickness of... 

Surface analyses, such as with X-ray photoelectron spectroscopy (XPS = ESCA), scanning electron microscopy (SEM), and dispersive X-ray analysis (EDX, WDX) are discussed in Section 17.7 because they are used routinely in characterizing vinyl composites. They are also useful in other connections, such as changes to vinyl surfaces from weathering or exposure to aggressive media. Fourier transform infrared (FTIR) analysis is also discussed in Section 17.7. 

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]. 

Other techniques in which incident photons excite the surface to produce detected electrons are also Hsted in Table 1. X-ray photoelectron Spectroscopy (xps), which is also known as electron spectroscopy for chemical analysis (esca), is based on the use of x-rays which stimulate atomic core level electron ejection for elemental composition information. Ultraviolet photoelectron spectroscopy (ups) is similar but uses ultraviolet photons instead of x-rays to probe atomic valence level electrons. Photons are used to stimulate desorption of ions in photon stimulated ion angular distribution (psd). Inverse photoemission (ip) occurs when electrons incident on a surface result in photon emission which is then detected. 

X-ray photoelectron spectroscopy (XPS) is currently the most widely used surface-analytical technique, and is therefore described here in more detail than any of the other techniques. At its inception hy Sieghahn and coworkers [2.1] it was called ESCA (electron spectroscopy for chemical analysis), hut the name ESCA is now considered too general, because many surface-electron spectroscopies exist, and the name given to each one must be precise. The name ESCA is, nevertheless, still used in many places, particularly in industrial laboratories and their publications. Briefly, the reasons for the popularity of XPS are the exceptional combination of compositional and chemical information that it provides, its ease of operation, and the ready availability of commercial equipment. 

Electron Spectroscopy for Chemical Analysis (ESCA) or X-Ray Photoelectron Spectroscopy (XPS)... 

Table 8 shows results obtained from the application of various bulk and surface analysis methods to lithium metal at rest or after cyclization experiments, as well as at inert and carbon electrodes after cathodic polarization. The analytical methods include elemental analysis, X-ray photoelectron spectroscopy (XPS or ESCA), energy-dispersive analysis of X-rays (X-ray mi-... 

X-ray photoelectron spectroscopy (XPS) electron spectroscopy for chemical analysis (ESCA) X-rays electrons 5nm yes quantitative 10 pm (scanning) >10 pm surface composition... 

Other techniques utilize various types of radiation for the investigation of polymer surfaces (Fig. 2). X-ray photoelectron spectroscopy (XPS) has been known in surface analysis for approximately 23 years and is widely applied for the analysis of the chemical composition of polymer surfaces. It is more commonly referred to as electron spectroscopy for chemical analysis (ESCA) [22]. It is a very widespread technique for surface analysis since a wide range of information can be obtained. The surface is exposed to monochromatic X-rays from e.g. a rotating anode generator or a synchrotron source and the energy spectrum of electrons emitted... 

X-ray photoelectron spectroscopy (XPS), which is synonymous with ESCA (Electron Spectroscopy for Chemical Analysis), is one of the most powerful surface science techniques as it allows not only for qualitative and quantitative analysis of surfaces (more precisely of the top 3-5 monolayers at a surface) but also provides additional information on the chemical environment of species via the observed core level electron shifts. The basic principle is shown schematically in Fig. 5.34. 

Surface composition and morphology of copolymeric systems and blends are usually studied by contact angle (wettability) and surface tension measurements and more recently by x-ray photoelectron spectroscopy (XPS or ESCA). Other techniques that are also used include surface sensitive FT-IR (e.g., Attenuated Total Reflectance, ATR, and Diffuse Reflectance, DR) and EDAX. Due to the nature of each of these techniques, they provide information on varying surface thicknesses, ranging from 5 to 50 A (contact angle and ESCA) to 20,000-30,000 A (ATR-IR and EDAX). Therefore, they can be used together to complement each other in studying the depth profiles of polymer surfaces. 

The films were characterized using x-ray powder diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The photoelectron spectroscopy utilized a Vacuum Generators ESCA Lab II system with Mg(Ka) radiation. Binding energies (BE) were measured with respect to the surface C(ls) peak (284.5 eV) which was always present In these films. Scanning electron microscopy was done with a JEOL JSM-35C system. 

We shall concern ourselves here with the use of an X-ray probe as a surface analysis technique in X-ray photoelectron spectroscopy (XPS) also known as Electron Spectroscopy for Chemical Analysis (ESCA). High energy photons constitute the XPS probe, which are less damaging than an electron probe, therefore XPS is the favoured technique for the analysis of the surface chemistry of radiation sensitive materials. The X-ray probe has the disadvantage that, unlike an electron beam, it cannot be focussed to permit high spatial resolution imaging of the surface. 

The work of Siegbahn s group who, in the 1950s, improved the energy resolution of electron spectrometers and combined it with X-ray sources. This led to a technique called electron spectroscopy for chemical analysis (ESCA), nowadays more commonly referred to as X-ray photoelectron spectroscopy (XPS) [6]. Siegbahn received the Nobel Prize for his work in 1981. Commercial instruments have been available since the early seventies. 

As representative techniques of the second group, we discuss two methods x-ray photoelectron spectroscopy (XPS), sometimes referred to as electron spectroscopy for chemical analysis (ESCA) and Auger electron spectroscopy (AES). The main principle of the first method (XPS) is the excitation of electrons in an atom or molecule by x-rays. The resulting electrons carry energy away according to the formula... 

Photoelectron spectroscopy involves detection and analysis of the photoelectrons produced by interaction of radiation with a solid. This radiation may be X-rays (for X-ray photoelectron spectroscopy, XPS or ESCA) or ultraviolet radiation (UPS) it causes the removal of a single core or valence electron, respectively. The kinetic energy, Ek, of these electrons is given by the following equation ... 

---