Photoionization cross section atomic subshell

Table 6.6 Theoretical atomic subshell photoionization cross-sections for MoVTeNb-related valence band orbitals at different photon energies, according to the calculations ofYeh and Lindau [177].

The theoretical calculation for peak intensity of photoelectron spectram has been carried out in the framework of DV-Xa method. First we ealculate the atomic subshell photoionization cross sections. The photoionization cross section for atomic orbital... 

D.A. Vemer, D.G. Yakolev, I.M. Band, M.B. Trzhaskovskaya, Subshell photoionization cross sections and ionization energies of atoms and ions from He to Zn, At. Data Nucl. Data Tabl. 55 (1993)233. 

For outer subshells of the encaged atom, the ionization thresholds of which vary from a few eV to a few tens eV, the dynamical-cage model is required. The photoionization cross section of the encaged atom in the dynamical-cage approximation will be marked with a tilde sign 5 s and... 

The a s are the relative photoionization cross-sections of a parti( ular atomic subshell they have been obtained by a fitting procedure on reference systems. 

The calculations of the photoionization cross section of the atomic subshell have previously been performed using Hartree-Fock-Slater one-electron model by several workers. Table 1 compares the photoionization cross sections of the atomic orbital electrons obtained in the present work with those previously reported by Scofield for some atoms. Scofield has used the relativistic wave functions. The... 

The value of the photoionization cross section varies for a different photon energy. Figure 2 plots the photoionization cross sections of the atomic orbitals for Fe atom as a function of the photon energy. Yeh and Lindau have reported the photoionization cross sections of atomic subshells for various photon energies. The present result is in a good agreement with the previous calculations. 

Whenever an orbital does not have spherical symmetry (quantum number 10) any subshell splits into two levels with quantum numbers j = 1 s. This splitting is therefore increasing with the atomic number on a given subshell (constant n, 1) and with a decrease in 1 at constant n. Assuming the two levels have the same photoionization cross-section, the ratio of peak areas in the doublet is given by the ratio of their degeneracies (2j -i- 1). 

Fig. 4. Calculated photoionization cross sections for several atomic subshells in cerium as a function of photon energy (Yeh and Lindau 1985).

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