The Valence Region and Comparison with Studies of Gaseous Molecules

The Valence Region and Comparison with Studies of Gaseous Molecules 

For the chemist, one of the most interesting consequences of the development of photo-electron spectrometry since 1962 is the experimental confirmation of the positions of penultimate MO in the valence region (6, 206), which can roughly be 

When comparing the lowest I of numerous gaseous halides (6) it is striking that the values usually are within 1 eV from 

In the molecules CF4 and SF6, not only the a orbitals mainly constructed from F2 but also the deeper set of a orbitals corresponding energy-wise to F2s (58, 124) at I =40.3 ( 2) and 43.8 eV ( i) in CF4 and I =39.3 (eg with l =2), 41.2 (t u with one angular node) and 44.2 eV (a g totally symmetric) in SF6 is separated by effects of chemical bonding. However, these exceptional cases have the F—F distance much shorter than twice the ionic radius of F, and the overlap integral (124) between two adjacent F2s orbitals is 0.11 in CF4 and 0.05 in SF6 to be compared with 5 10 12 between two FIs orbitals in CF4. 

Diatomic halides were first studied as HX by Lempka, Passmore and Price (211) showing slightly higher I than Eq. (24). It is possible by high-temperature equipment (212—214) to study diatomic alkaline halide molecules (or ion-pairs) 

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