[en] The study of the reaction dd → ³He n in the intermediate energy region shows numerous analogies with the pd → dp reaction and allows to test the nucleon and N* exchange in the t channel versus other possible reaction mechanisms. A set of eight differential cross sections of the reaction dd → ³He n of which CMS angle varies from nearly 0⁰ to 60⁰, have been measured from 1.1 to 2.5 GeV/c. The energy dependence study of our data shows a s channel effect in the total cross section, in dσ/dt at fixed values of t and in the exponential slope. This s channel effect can be interpreted as an excitation of a virtual Δ₃₃ responsible of a part of reaction mechanisms. (auth.)