Protonated water clusters in TPC’s

Water vapour is added to the ALICE TPC gas to enhance its stability. These polar molecules create large protonated water clusters around a H+ core. In this context, the reactions H3O+(H2O)n−1+H2O→H3O+(H2O)n ( n =1–9) were studied in the gas phase. Structures for these clusters are suggested and the most stable structures for each cluster size are shown. The thermodynamic parameters ΔHn−1,n0 , ΔGn−1,n0 , ΔSn−1,n0 and equilibrium constants Kn−1,n for the reaction were calculated to determine the size of the water clusters. The results are close to experimental data found in the literature. Protonated water clusters at stp have a size of 6–9 which corresponds to a mass of 127.1–181.2g/mole .