Auger amplitude

Fig. 11. Auger sputter profiles (Auger amplitude vs. ion-bombardment time) for unreduced (open points, dashed curves) and reduced (solid points and curves) Rh/(single crystal) Ti02 model catalysts. Curves for Ti and O have been shifted up for clarity. (After Ref. 27.)...

With a strong orthogonality condition imposed on the scattered electron orbital, fulfilling the killer condition Po) = 0 the Auger amplitude resulting from the Fermi golden rule expression (Eq. 3.37) takes the form... 

The surface reactions were investigated by a combination of AES and TPR studies, with authentic samples of the expected products being used to calibrate the signals from the two techniques. The Auger spectra were obtained with a single pass cylindrical mirror analyzer operated with a modulation amplitude of 4 eV the surface heating rate in the TPR studies was 2 K/s. 

As a first approximation, direct double photoionization will be neglected. This is often justified because the cross section for double photoionization in outer shells, and hence also the corresponding amplitude, is much smaller than the cross section for single photoionization in an inner shell. Therefore, the Auger decay has... 

Auger electron current as both are proportional to the number of excited atoms. The relative amount of an element on the surface can then be determined by simple measurement of the Auger peak height or area, followed by comparison with a standard. Clearly such a method is applicable only when all parameters are held constant, though methods exist that allow values for Auger currents to be obtained that ate independent of the modulation amplitude used... 

Now assume that P = af af and Q — a a. Following the same reasoning as above we see that m> = Al + 2> if 0> = V>isan N-electron state. The poles and residues yield energy differences and overlap amplitudes of Auger spectra, respectively. Two-electron propagators of the type afia a yy have in... 

This diagram represents ionization of a core electron via a shape resonance orbital. In the first step the core electron is excited to an orbital above the ionization threshold that has a large amplitude n the vicinity of the molecule. The second step represents separation of the electron from the molecule. The subsequent relaxation then is identical to the situation where the core electron is ionized directly. These channels, depicted in Table II, are Auger decay... 

The sulfation of ceria-only model catalysts was initially considered to develop a characteristic baseline of sulfur adsorption to reference the mixed oxide systems. Auger analysis of the systems prior to and after experimentation facilitated semi-quantitative analysis of sulfur adsorption on ceria. The Auger spectra were normalized with respect to the cerium A4AW transition (661 eV) and the amplitude of the sulfur ZMM transition (152 eV)... 

Figure 15.10. Amplitudes of the various Auger peaks from a nichrome film on a silicon substrate as a function of the amount of material sputter-etched from the film. From R. E. Weber, J. Crystal Growth, 17, 342 (1972), by permission of the author and the North Holland Publishing Company.

The probability amplitude for the radiationless transition of the Auger process then is... 

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