Electronic characterization techniques photoelectron spectroscopy

Ffirai and Toshima have published several reports on the synthesis of transition-metal nanoparticles by alcoholic reduction of metal salts in the presence of a polymer such as polyvinylalcohol (PVA) or polyvinylpyrrolidone (PVP). This simple and reproducible process can be applied for the preparation of monometallic [32, 33] or bimetallic [34—39] nanoparticles. In this series of articles, the nanoparticles are characterized by different techniques such as transmission electronic microscopy (TEM), UV-visible spectroscopy, electron diffraction (EDX), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) or extended X-ray absorption fine structure (EXAFS, bimetallic systems). The great majority of the particles have a uniform size between 1 and 3 nm. These nanomaterials are efficient catalysts for olefin or diene hydrogenation under mild conditions (30°C, Ph2 = 1 bar)- In the case of bimetallic catalysts, the catalytic activity was seen to depend on their metal composition, and this may also have an influence on the selectivity of the partial hydrogenation of dienes. 

Let us take 1978 as the starting point. Massoth [51] then published an extensive review of what was known about the structure of HDS catalysts. Characterization was essentially based on techniques such as X-ray diffraction, electron microscopy, photoelectron spectroscopy, electron spin resonance and magnetic methods. Massoth was rather unhappy with the state of affairs in 1978. He was struck by the ...diversity and apparent contradictions of results and interpretations... It almost seems as though everyone is working with a different catalyst . 

The elemental composition, oxidation state, and coordination environment of species on surfaces can be determined by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) techniques. Both techniques have a penetration depth of 5-20 atomic layers. Especially XPS is commonly used in characterization of electrocatalysts. One common example is the identification and quantification of surface functional groups such as nitrogen species found on carbon-based catalysts.26-29 Secondary Ion Mass spectrometry (SIMS) and Ion Scattering Spectroscopy are alternatives which are more surface sensitive. They can provide information about the surface composition as well as the chemical bonding information from molecular clusters and have been used in characterization of cathode electrodes.30,31 They can also be used for depth profiling purposes. The quantification of the information, however, is rather difficult.32... 

In the last century, many microstructural characterization techniques have been developed, such as electron microscopy, atomic tunneling microscopy, photoelectron spectroscopy, Raman spectroscopy, etc. The structure of the OLED-based displays is such that many pixels are arranged orderly in the x-y plane. The size and number of pixels determine the resolution and size of the display. Along the z-axis, several layers are stacked on each other. These layers... 

The main techniques employed for the characterization of clusters include UV/vis optical absorption, luminescence, mass spectrometry, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR). Single crystal X-ray diffraction (XRD) has been used to determine the structures of a few clusters [17-19]. 

Other spectroscopic techniques used to characterize iron oxides are photoelectron (PS), X-ray absorption (XAS), nuclear magnetic resonance (NMR) (Broz et ah, 1987), Auger (AES) (Seo et ah, 1975 Kamrath et ah, 1990 Seioghe et ah 1999), electron loss (EELS)), secondary ion mass (SIMS) and electron spin resonance (ESR) spectroscopy (Gehring et ah, 1990, Gehring Hofmeister, 1994) (see Tab. 7.8). Most of these tech-... 

We begin with the most routine characterization methods—electrochemical methods. We then discuss various instrumental methods of analysis. Such instrumental methods can be divided into two groups ex situ methods and in situ methods. In situ means that the film on the electrode surface can be analyzed while the film is emersed in an electrolyte solution and while electrochemical reactions are occurring on/in the film. Ex situ means that the film-coated electrode must be removed from the electrolyte solution before the analysis. This is because most ex situ methods are ultra-high-vacuum techniques. Examples include x-ray photoelectron spectroscopy [37], secondary-ion mass spectrometry [38,39], and scanning or transmission electron microscopies [40]. Because ex situ methods are now part of the classical electrochemical literature, we review only in situ methods here. 

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