Remarques sur la dissociation des molCcules azotCes sous l'impact Clectronique (*) Par Jacques COLLIN (Likge) SUMMARY. -Different ways of approach have been proposed for the study of bond breakage probabilities under electron impact. The most interesting ones are calculation of stabilities, rupture coefficient and (( indices de fragmentation )), as proposed by Pahl, Viallard and Magat.
Nitrogen compounds have been studied in this way ; it comprises aliphatic amines, nitrites, nitroderivatives and dialkylnitrosamines. Comparison is made with alcohols and hydrocarbons.
The use of ((indices de fragmentation moyenss in a special way appears to be fruitful in that it gives an I ( index spectrum )) quite different for amines and hydrocarbons. The greatest fragility of amines is found to be on the C,-C, bond adjacent to the nitrogen atom. The same fact is found for the alcohols.
Reference is made to the possibility of predicting the charge distribution in the molecule after the electron impact excitation. A possible explanation of the C,-C, bond fragility is proposed, due to the fact that ionization is taking place on the nitrogen atom.
Influence of the variation of bombarding electron energy on the stability and total ionization efficiency has been consid-ed with special reference to n-propylamine, i-propylamine, the two butanes, butene-1 and butadiene 1-3. Unsaturated compounds appear to be more sensitive to electron energy variation and their stability is much greater than for saturated compounds. This is explained by x electron delocalisation. This work shows that electron energy transfer probability functions proposed by Eyring and coworkers seem to be roughly correct. Specific total ionization, that is total ionization per micron, is shown to be almost the same for the six compounds considered, and to vary practically in the same way with electron energy, independently of the molecular structure.
(*) Travail effectu6 avec l'aide de 1'I.R.S.I.A.