Étude du Comportement D'isomères Géométriques Sous L'impact Électronique. II. Les Cis et Trans Hexahydroindanes

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Abstract
The influence of geometrical isomerism on the behaviour of cis and trans hexahydroindanes under electron impact appears in two different ways.Firstly, mass spectra, although qualitatively identical, show important differences between abundances of several main fragment ions, especially C5H7+ and C6H9+. Relative abundances of molecular ions also differ, by about 15%, and indicate a greater stability of ionized trans isomer.Secondly, from the standpoint of energetics, two results are to be noticed. (a) Ionization potentials of cis and trans hexahydroindanes are the same within experimental uncertainties, which means that an effect due to isomerism appears in both ionized molecules. (b) Appearance potentials of the main fragment ions show that a lower energy is required to dissociate ionized cis hexahydroindane into fragments, which has to be related to the energy provided by steric conformation in this molecule.These results are in perfect agreement with those previously obtained in a study of cis and trans decalines.