Single photon double valence ionization of vinyl halides

Abstract: Using a He lamp and a magnetic bottle spectrometer we measured the single ionization potential and the double ionization potential of C2H3Br, C2H3Cl, C2H4 and recorded their spectra at a photon energy of HeIIα and HeIIβ. The coincidence maps obtained from our measurements indicate that primarily direct double ionization occurs in these molecules. Due to the fact that ionization processes in this thesis involve valence electrons, we have tested the validity of an empirical equation,from which the distance of the holes created in the dication can be estimated if the values of the single and double ionization potential are known. It was found that the bond length between the carbon atoms was increased due to the repulsion of the holes created in the outermost valence orbitaland our data are in agreement with theoretical predictions, but in order to verify the applicability of this empirical relation on solid grounds, ab initio quantum chemical calculations are desired.