L'apparition des ions C2H3+ à partir de C2H3F par photoionisation non-résonante. Une analyse de la surprise de l'énergie translationnelle.

It is shown that for a photon energy of 16.85 eV the translational energy surprisal of the C2H3++F dissociation products from C2H3F+ has a bimodal behaviour. The possibility of considering the bimodal surprisal as due to the superposition of two translational energy distributions is consistent with the theoretical assumption of the concurrence of two channels in this dissociation process. The characteristics of these distributions, i.e. the energy width and the relative abundance, are in agreement with the results of an ab initio quantum-mechanical calculation of the dynamics of this dissociation. They are consistent with the simultaneous occurrence of a statistical dissociation of C2H3F+(X2A') into C2H3+(X1A') and an isolated state dissociation of C2H3F+(C2A") into C2H3+(a3A"). Negative lambda values obtained for the surprisal of both these distributions indicate an inversion of the translational level population of the dissociation products