L-subshells

The dominant non-radiative branches for the filling of the created ls-hole in neon are the K-LL Auger transitions. As can be seen in Fig. 2.5 there are different ways for the two holes to be distributed in the final state in the L-subshells L L2 3, and the corresponding Auger transitions can be grouped into K-L,L,... 

S. Reusch, H. Genz, W. Low, A. Richer, A method to determine L-subshell ionization cross sections for medium and heavy elements, Z. Phys. D 3 (1986) 379. 

Thus, an important development has occurred because of the + / rule. The fourth shell has started filling before the third shell has been completed. This is the origin of the transition series elements. Thus, titanium, atomic number 22, has two electrons in its l subshell, two electrons in its 2s subshell, six electrons in its 2p subshell, two electrons in its 3s subshell, six electrons in its 3p subshell, two electrons in its 4s subshell, and its last two electrons in the 3d subshell. 

The analysis can also be carried out using the standard computer code. However, the procedure for analysis is the same as described earlier. PIXEF (for PIXE-fit) the Livermore PIXE spectrum analysis package has been developed by Antolak and Bench (1994). This software initially computes an approximation to the background continuum, subtracts from the raw spectral data and the resulting X-ray peaks are then fitted to either Gaussian or Hy > ermet distributions. The energy dependent ionization cross-sections for each element s K-shell or L-subshell are procured from the analytical functional fit, while the subshell and total photoelectric cross-sections are determined directly from the Dirac-Hartree-Slater calculations of Scofield. Schematic of a typical PIXE spectrum is as shown in Fig. 1.16. 

The fluorescence yield values (tu ) of the L-subshell and the Coster-Kronig transition probabilities (/y) are listed by Krause (1979). The relative radiative transition probabilities Fij) of the ith subshell contributing to the jth peak can be taken from Cohen (1990). The ionization cross-sections can be theoretically calculated using the ECPSSR theory (see Sect. 1.11.3 for different theories on ion-atom collision). 

The ionization cross sections of the individual L subshells may provide a sensitive test for details of the ionization process as has been demonstrated for ion impact ionization. The binding energies of the three L subshells are comparable, but the corresponding wave functions differ significantly. Photoionization occurs dominantly by electric dipole transitions (A/ = 1), so that only a few final states are occupied. For ionization of the individual... 

In a recent photoionization measurement of Au L-subshell cross sections in the regime of the L edges agreement between experiment and theory was found within 2%, which is less than the expected experimental uncertainty (Figure 10). The experimental uncertainty partly arises from the use of a solid Au sample the absorption spectrum of solid Au exhibits fine structure oscillations which have not been taken into account in the data evaluation. The energy dependences of the Ly- and L2-subshell cross sections as predicted by theory are rather similar. For the Ly cross section the experimental slope is in agreement with theory, whereas there is indication that for the L2 cross section the experimental slope differs from the theoretical prediction. A possible explanation for the observed deviation is... 

Table 3. Compilation of Radiative (w), Auger (a), and Coster-Kronig (/) Decay Rates for L-Subshell Vacancies in 79AU or goHg" ...

Fluorescence yields adopted by Krause [5] are reported below. The same reference also provides sets of Auger yields (ax values) for K and L shells and Coster-Kronig yields (f values) for L subshells. Our tables do not refer to papers which deal with mean fluorescence yields for L or M shells as defined for instance in [6] which also gave some experimental L-subshell yields and f values (previous to 1966). See also [8] and other papers in the Proceedings of Int. Conf. on Inner-Shell Ion. Phenomena and Future Applications, April 17-22, 1972 . 

Table 2/50 gives also a (nonexhaustive) complementary list of references for the various L subshells of the heavy elements. Values for Os M subshells in Table 2/50 were calculated from theoretical transition rates in [T10]. 

There are many papers dealing with the intensity of X-ray spectral lines for the atomic numbers concerned here. We cannot give all the references. Some provide experimental values, mostly intensity ratios of emissions due to transitions towards a previously ionized K shell or L subshell they usually compare the experimental results to calculated values of emission rates or radiative transition probabilities. In fact the distinction is not always clearly made between transition probability Pab which is proportional to the number of photons emitted during the transition a - b and the intensity lab which is proportional... 

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