Nanoscale characterization of irradiation in biomolecular systems requires observation of novel features which are now achievable with the recent technical progress. This work is a central part in the development of DIAM which is a new experimental set-up devoted to irradiation of biomolecular clusters at the Institut de Physique Nucléaire de Lyon. The development of the cluster source and of a double focusing mass spectrometer leads to the production of intense beams of mass selected protonated molecular clusters. Combined with this mass selected cluster beams an innovative detection technique is demonstrated in collision induced dissociation experiments. The results contribute to the knowledge of the stability and the structure of the small protonated water clusters and mixed clusters of water and pyridine
