Auger electron nomenclature

The notation of Auger transitions uses the X-ray level nomenclature of Table 3.1. For example, KL L2 stands for a transition in which the initial core hole in the K-shell is filled from the L -shell, while the Auger electron is emitted from the L2-shell. Valence levels are indicated by V as in the carbon KVV transition. 

In principle, the same energy analyzer may be used for both XPS and AES and, consequently, the two techniques are often found in the same analytical instrument. The sources of the primary radiation for the two methods are a soft X-ray tube and an electron gun. The nomenclature employed to describe photoelectrons and Auger electrons is different XPS electrons are described by the appropriate quantum numbers, i.e. Is, 2p3/2, 3d5/2, 4f7/2, while Auger electrons are identified by the X-ray notation (shell name), i.e., K, L, M, N, and so on (Watts, 1990). 

The photopcaks are generally identified by referring to the quantum levels involved (Is, 2s, 2p3/2, etc.) whilst for the Auger electrons the spectroscopic nomenclature is used (K, L, M. etc.) to identify the levels involved. 

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. 

Figure 2.2 Demonstration of the two equivalent nomenclatures used for the description of inner-shell levels and X-ray transitions (also Auger transitions, see below). The vertical direction is regarded as the energy axis (but is not to scale here). On the left-hand side is given the notation which is frequently used in inner-shell spectroscopy, on the right-hand side the corresponding single-orbital quantum numbers with n, t and j being, respectively, the principal quantum number, the orbital angular momentum and the total angular momentum which includes the spin of the electron. Also shown are the main X-ray transitions with their spectroscopic notation (for a more complete plot which includes...

Nomenclature of an Auger transition is of the type Xj-YjZ, where Xj labels the first electron vacancy, Yj and Z,, the two vacancies created in the Auger process Y and Z may belong to different series. As an example K-L L2 means the initial hole is in the K shell, the two holes in the final state are in and Lg (or K-L Lg 3 when Lg and L3 are not separated). Transition energies and probabilities depend on the type of coupling between the two electrons involved in the process (see [5]). 

The Auger effect is characterized by an upper level valence electron relaxation into the vacant core-level state (after the initial photoionization), followed by an ejection of another electron in the valence level. In the nomenclature of the Auger effect, for example, for the KL1L23 transition in Fig. 2, the first shell corresponds to the core level in which the initial vacancy was created (K) either via photoemission from XPS or electron impact bombardment from an electron beam, the second... 

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