L’interprétation théorique des spectres de masse. Application au 1,3 butadiène

Institut de Chimie de l’Université de Liège, Belgique et Centre de Mécanique Ondulatoire Appliquée, 155, rue de Sèvres, Paris, 15 e, France.

Abstract

The processes occuring during ionization and fragmentation of molecules bombarded by monoenergetic electrons are examined. The absolute calculation of a mass spectrum requires namely the solution of two problems :

1) calculation of the electronic levels of the ion and 2) study of the transition probabilities to each of these levels. Such a procedure must however be completed by an assumption about the probability of rupture of the different chemical bonds in each electronic state. We assume in this work that the chemical bond with lowest bond order will dissociate.

The mass spectrum of butadiene is then calculated by this method using 1) the electronic levels calculated by means of a LCAO/SCF/CI treatment (¹⁰) and 2) an empirical solution of the transition probability problem proposed previously (¹¹).