Secondary emission adsorption

Correlations between surface species and emitted secondary ions are based on characterization of the surface adlayer by adsorption and thermal desorption measurements. It is shown that the secondary ion ratios RuC+/Ru+ and R CTVRuJ can be quantitatively related to the amount of nondesorbable surface carbon formed by the dissociative adsorption of ethylene. In addition, emitted hydrocarbon-containing secondary ions can be directly related to hydrocarbon species on the surface, thus allowing a relatively detailed analysis of the hydrocarbon species present. The latter results are consistent with ejection mechanisms involving intact emission and simple fragmentation of parent hydrocarbon species. 

In the forming of these polar bonds, electrons of the metals are withdrawn from the metal. The binding of electrons can be shown by the increase of the secondary electron emission (86,87), and conductivity measurements (88,89) and measurements of contact resistances (90,91) show that conduction electrons have been occupied by these bonds. The physical adsorption of a gas on a metallic surface, on the other hand, causes a slight increase of the conductivity of the metal (92,93). 

Fine structure experiments are often carried out with synchrotron sources, since the initial electron state is better defined for photoemission than for electron excitation. When core-hole decay is detected by Auger or secondary electron emission, the technique is surface sensitive. Core-hole decay can also be detected by fluorescence, or by adsorption of the incident photon beam. These methods are not intrinsically surface sensitive, but they are useful when the source atoms are exclusively located at the surface. 

The importance of surface and chemical analysis techniques in electronics corrosion testing cannot be overstated. These powerful tools contribute to solving problems and elucidating corrosion mechanisms in simple and complex systems. Chemical analysis techniques include infrared (IR), ultraviolet (UV), and RAMAN spectroscopy X-ray diffraction atomic adsorption emission and mass spectroscopy gas and liquid chromatography and optical and transmission electron microscopy. Surface analytical techniques include electron spectroscopy for chemical analysis (ESCA), Auger, secondary ion mass spectroscopy (SIMS), and ion scattering spectroscopy (ISS). These important techniques used in conjunction with corrosion tests are described in another section of this manual. 

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