Energy spectrum periodic-orbit structures

The increase in the number of fluorine atoms is correlated with a shift of about 1 eV per F atom to lower energies for the peak D, while the other peaks do not change appreciably. The spectrum predicted from the calculated band structure for PTFE is in good agreement with experiment, underlining once more that calculations of periodic polymers are quite successful in interpreting ESCA spectra. This agreement will be more comprehensive when allowance is made for the dependence of the ionization cross section of the crystal orbitals on their atomic constituents (intensity calculations), and correlation effects are also taken into account. Furthermore, better-resolved experimental spectra are probably also needed to check the detailed theoretical information obtained for relatively more complex polymers. 

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