KLL transition

At this point of the discussion, we would like just to mention the different behaviour of the modified Auger parameter between the two growth modes the evaporated films exhibit a singularity for both Al and Si KLL transitions around Al thicknesses 10-20 A while the sputtered films show this singularity only for a j with a monotonous increase of the a., parameter. We have no present explanation for these observations, But we want to present them as an experimental evidence for differences in long range electronic properties of these interfaces. 

Well-ordered AI2O3 films have been prepared using an A1 deposition rate of 0.5 MLE.min (equivalent monolayer, calibrated on an Mo(llO) substrate using AES and TPD), at a background O2 pressure of 7 x 10 Torr, and an Mo(llO) substrate temperature at 300 K [58]. Following deposition, the films were annealed to 1200 K in O2 to improve the film order. Figure 1 shows representative AES spectra of alumina films at two different thicknesses [58]. An AES spectrum of a 2.0-nm film has a predominant Al (LVV) transition at 45 eV and an O (KLL) transition at 500 eV. The absence of a peak at 68 eV, characteristic of Al°, indicates that the film is fully oxidized. Features attributable to the Mo(llO) substrate can be seen in the 100-250-eV region. The thickness of the oxide films was calculated from the attenuation of the AES intensity ratio of the Al (LVV) feature relative to the Mo(MNN) feature. 

FIGURE 10. Sputter depth profile of an oxidized aluminum sample, (a) Peak-to-peak heights of the O and Al KLL transitions (Figure 9) as a function of sputter time, (b) Composition as determined by Eq. (5) using the peak-to-peak heights of (a), (c) Composition as determined by Eq. (5) but fitting the spectra to sums of the aluminum oxide and metal line shapes. Note the apparent decrease in the Al concentration and the increase in the O concentration at the interface of (b). 

XPS and XAES spectra were recorded under two conditions (a) at constant takeoff angle <]> of 90° (normal emission), using the Bremsstrahlung component of unmonochromatized Al Kq radiation to excite the Auger Si KLL transition ... 

Auger electron) from the atom. This is a radiationless process leading to double ionization. A transition of an electron from an L shell to a K shell vacancy, accompanied by the ejection of an L shell electron, is represented as a KLL transition. The energy of the ejected electron in KLL transition is Auger- LL Here is the energy of the atom... 

Table 2. Comparison of theoretical relative and total absolute KLL transition rates of neon with experiment. The relative rates are normalized to the KL.2 2 rate, the total...

In X-ray notation the Auger transition shown in Fig. 2.1 would therefore be labeled KL2L3. In this coupling scheme, six Auger transitions would be possible in the KLL series. Obviously, many other series are possible (e. g., KLM, LMM, MNN). These are discussed more fully in Sect. 2.2, dealing with AES. 

The nomenclature used in AES has also been mentioned in Sect. 2.1.1. The Auger transition in which initial ionization occurs in level X, followed by the filling of X by an electron from Y and ejection of an electron from Z, would therefore be labeled XYZ. In this rather restricted scheme, one would thus find in the KLL series the six possible transitions KLiLi, KL1L2, KL1L3, KL2L2, KL2L3, and KL3L3. Other combinations could be written for other series such as the LMM, MNN, etc. 

Advantages of silicon x-radiation include the access of aluminum and magnesium core level (Is) lines and the corresponding (KLL) Auger transitions for chemical state identification and improved quantitation, because these lines are at least 10 times more intense than the corresponding (2p) or (2s) lines. The construction of an off-axis reactor has produced a simple, versatile and inexpensive system easily adapted to any vacuum system. The role of AES and SAM in catalyst research will also be highlighted by examples. 

The Roentgen luminescence (i.e., the emission of an X-ray quantum) is significant only for elements with Z > 20. The ratio of the Auger effect probability to that of Roentgen luminescence is WA/Wx = 106/Z4. 43 In Table II we present the values of the probabilities WA and VYX together with the fluorescence yield for the KLL Auger transition for a number of... 

Table 6.2 Comparison of the branching ratios of the KK-KLL Auger transitions in doubly core-ionized Ne...

CsCl at 200°C for 14 days, is shown in Figure 4. Before this spectrum was collected, the cube was sputtered with Ar ions to remove surface contamination. Two Cs MNN transitions arise at 554 and 566 eV (6) and the larger 0 KLL peak is at 506 eV. Superimposed on Figure 4 is a spectrum of natural pollucite, recorded under the same instrument conditions and corrected for a -4 eV positional difference observed in each of the three peaks. The same charging shift was observed in the Si peaks (not shown in Figure 4), which were found at 76 eV (cube) and 72 eV (natural pollucite). Transitions from four elements, Al, Si, 0, and Cs, were observed in both spectra. Potassium was not detected in either spectrum. 

SOLID-STATE AND CHEMICAL EFFECTS ON KLL AUGER SPECTRA (DIAGRAM TRANSITIONS) OF 3d TRANSITION METALS EXPERIMENTS AND MODELS OF INTERPRETATION... 

A striking feature of the core Auger spectra is the multiplet structure of the diagram lines. Looking at the case of, for example, KLL Auger transitions in the... 

Figure 14.2 Multiplet energies in KLL Auger spectra of some 3d transition metals, calculated using configuration B for metal clusters, in comparison with experimental data published earlier. Reproduced with permission from Ref. [5].

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