Correlated detection of neutral and charged fragments in collision induced fragmentation of molecular clusters

Abstract We report on collision induced fragmentation of isolated molecular nanosystems studied with an event by event detection technique including the correlated detection of both neutral and charged fragments. This work focuses on the dissociation induced by collisional excitation without ionization and electron-capture. Two molecular cluster cations are investigated: the collision of protonated hydrogen clusters at 60 keV/amu with helium targets and that of protonated water clusters at 8 keV with an argon gas. In addition to the molecular evaporation process the dissociation channel leading to the production of the H 3 + or H 3 O + molecular cations (loss of all the molecules) is observed with an unexpected abundance. The cross section for the production of these cations is observed to increase with the number of molecules in the cluster. Such an increase cannot be associated with the direct collisional excitation of the cation core of the cluster.