A theoretical approach was developed to describe secondary particle emission in heavy ion collisions, with special regards to pre-equilibrium {alpha}-particle production. Griffins model of non-equilibrium processes is used to account for the first stage of the compound system formation, while a Monte Carlo statistical approach was used to describe the further decay from a hot source at thermal equilibrium. The probabilities of neutron, proton and {alpha}-particle emission have been evaluated for both the equilibrium and pre-equilibrium stages of the process. Fission and {gamma}-ray emission competition were also considered after equilibration. Effects due the possible cluster structure of the projectile which has been excited during the collisions have been experimentally evidenced studying the double differential cross sections of p and {alpha}-particles emitted in the E=250MeV 16O +116Sn reaction. Calculations within the present model with different clusterization probabilities have been compared to the experimental data.
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