Core ionization energies

Saethre and coworkers101 reported the Cls and halogen np core ionization energies of haloethanes and haloethenes. The effects observed were ... 

The shifts of core ionization energies in bulk samples such as these just presented are typically interpreted in terms only of the molecular changes that influence the shifts. However, solid-state effects could also contribute to the experimental trends, particularly for molecules that have very strong intramolecular interactions in the solid phase. A recent papef has addressed the possibility that the shifts that have been observed in the bulk phase XPS of porphyrins... 

FIGURE 24. Correlation between core ionization energy and proton affinity for arsenic and phosphorus compounds. Reprinted with permission from Reference 90. Copyright (1979) American Chemical Society... 

SHELL EFFECTS AND HOMOTHETIC EXPRESSIONS FOR ELECTRON RELAXATION AND OTHER CORRECTIONS TO 2p-CORE IONIZATION ENERGIES AND SPIN-ORBIT SPLITTING FOR ATOMS FROM Cl TO Ba... 

In this paper, we shall present a procedure for evaluating electron relaxation, inner-core correlation, and Breit, qed, and nuc corrections to 2p-core ionization energies and spin-orbit splitting in molecular systems, from tabulated results on atoms from Cl to Ba, excluding transition elements. 

In Table 1 we have gathered measured values of 2p-core ionization energies and spin-orbit splitting of atoms from A1 through Ba [25]. 

However, the second-order finite differences involve, in their computation, four values around each considered point, which may therefore be affected by their anomalies. Due to the irregularities occurring with fully filled and half-filled shells and the transition-element series, the discrete derivatives show an oscillating behavior, similar to that appearing in the Is- and 2s-core ionization energy variations [9]. 

Table 1. For elements from A1 (Z = 13) to Ba (Z = 56), measured 2p-core ionization energies [25b] and resulting spin-orbit splitting A (in eV). Energy values are given as being accurate to within 0.3-0.7 eV.

Figure 1. Experimental variations of 2p-core ionization energies (in eV) for atoms from A1(Z = 13) to Ba(Z = 56). Upper left. 2p /2 and 2p3/2 energies lower left, their weighted-average second-order discrete derivative, as functions of Z upper right spin-orbit splitting between the 2pi/2 and 2p3/2 levels lower right, its second derivative, as functions of Z. On the derivative diagrams shell effects appear about fully filled and half-filled shells and near filling irregularities of the transition elements.

The computations of 2p-core ionization energies were performed using a pattern similar to that used for Is- and 2s-core ionization energies [9]. Here again we have used Bruneau s multiconfiguration Dirac-Fock (MCDF) ab initio program [26-28], which is based on a numerical resolution of the Dirac equation corrected for Breit terms, vacuum polarization, and radiative (qed) contributions, and nuclear size and motion (nuc) effects. 

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