ESCA spectrum of methane

The ESCA spectrum of methane is presented in Fig. 1.12, where it can clearly be seen to be consistent with molecular orbital theory. There are two bands for the valence electrons at 12.7 and 23.0 eV, in addition to the band for the core electrons at 291 eV. It should be emphasized that these values are the binding energies of electrons in the three orbitals of differing energy, and are not the energies required for successive ejection of first one, then a second, and then a third electron. The intensities bear no relation to the number of orbitals or number of electrons, and differ from each other because the cross sections for ionization are different. 

For a review, see Photoelectron Spectroscopy, by C. R. Brundle and M. B. Robin, in Determination of Organic Structures by Physical Methods, Vol. 3, F. C. Nachod and J. J. Zuckerman (eds.). Academic Press, New York, 1971, Chap. 1. 

Gelius, in Electron Spectroscopy, D. A. Shirley (ed.), American Elsevier Publishing Company, New York, 1972, pp. 311-334. 

in Conformational Analysis Scope and Present Limitations, G. Chiurdoglu (ed.). Academic Press, New York, 1971, p. 129. 

The ethyl cation presents a case in which two alternative geometries have been considered as representing the energy minimum. A number of MO calculations have 

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There is experimental support for this MO pattern. The ESCA spectrum of methane is illustrated in Figure 1.16. It shows two peaks for valence electrons at 12.7 and 23.0 eV, in addition to the band for the core electron at 291.0 eV. Each band... 

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