ARXPS

PD (covers a variety of other acronyms, like ARPEFS, ARXPD, ARXPS, ARUPS, NPD, OPD, PED) yes 88 7.9... 

Recent developments have allowed for more detailed studies of polymer surface morphology by ESCA. Angle-resolved ESCA (ARXPS) allows for providing chemical compositions from shallower depths. By varying the angle of incidence different depths can be probed, and procedures have been developed to arrive at three-dimensional reconstruction of the surface. An example is shown in Figure 2, where a PVC/PMMA polymer blend has been analysed using such an approach [9]. 

A general term for structure - sensitive photoemission techniques, including ARPEFS, ARXPS, ARUPS, and ARXPD. 

Similar to ARXPS and ARPEFS. The angular variation in the photoemission intensity is measured at a fixed energy above the excitation threshold to provide structural information. 

Electrons photoemitted from atomic core levels are detected as a function of energy. The shifts of core-level energies give information on the chemical environment of the atoms (see ARXPS, ARXPD). 

According to ARXPS, Fe(II) is located in the outer parts of the anodic oxide and remains trapped up to very positive potentials, especially in alkaline, but also weakly acidic electrolytes. Similar to the situation of Fe/Al alloys, its oxidation is prevented due to the poor conductivity of a large Si02 content at the metal surface, i.e. in the inner parts of the film [79]. Fe(II) oxidation requires electronic conductivity from the outer parts of the passive layer to the metal surface. 

ARXPS Angle-Resolved X-ray Photoemission Spectroscopy The diffraction of electrons photoemitted from core-levels gives structural information on the surface. 

The most promising techniques for obtaining detailed surface structural information about molecular adsorbates rely on electron diffraction in one way or another. These include LEED,/27,28,29/ IV-HREELS,/30/ EAPFS,/31/ SEELFS,/32,33/ EXELFS,/34,35/ ARUPS, ARXPS, ARPEFS,/36,37,38/ PE-SEXAFS, SEXAFS, EXAFS, and NEXAFS (XANES). These and other techniques have been discussed above in part 2, and were summarized in Table I. Among these techniques, LEED has been the most productive. 

This yields sensitivity to the surface within a photo-electron mean free path length of the photoexcited atom, which can be chosen with chemical selectivity. Compared to ARUPS, ARXPS is a more convenient approach for the extraction of structural information, since core-level excitations are more easily described than valence-level excitations. Angle-resolved detection is normally used to obtain the most complete structural information, which is interpreted in a procedure very similar to that of LEED with full simulation of the electron emission intensity as a function of energy or angle. 

If we limit ourselves to observed LEED patterns, we find that over the years about 2000 ordered structures have been reported./202/ Among these, perhaps 180 have been structurally solved by various techniques of surface crystallography. Intensity analyses of low-energy electron diffraction have contributed about 150 of these. The remaining 30 structures were obtained primarily with ion scattering (MEIS, HEIS), SEXAFS or photoelectron diffraction (NPD, ARXPS). 

Figure 7. Experimental principles of Angular Resolved X-ray Photoelectron Spectroscopy (ARXPS). Reproduced with permission from Ref. 37. Copyright 1985 Research and Development.

Figure 8. ARXPS spectra of silicon 2p region of silicon with a native oxide showing multiple oxidation states. A)6 s 10 ...

Two different stages for silver deposition on platinum can be described one at 1.1 V vs. RHE responding to a silver-platinum alloy electrodissolution (overlapped with the oxygen electroadsorption at free platinum sites) and the other at 0.65 V due to the silver oxidation (from the onset of the bulk deposition process) deposited on the former surface alloy [88,89]. The former process splits into two peaks when the potentiostatic ageing is performed. The spectroscopic techniques such as XPS and ARXPS (angle resolved x-ray photoelectron spectroscopy) were used to determine the chemical composition of the silver films on the platinum in an acid solution [92], The technique was not able to discern between the presence of silver oxides and sulfates, only an energy shift of the clean silver 3d5/2 band at a upd level of —0.5 eV was detected. 

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