Knowledge Bank

Mid-infrared photofragmentation spectra of mass-selected proton-bound cluster ions of the type $Bn\dots H-A+$ have been recorded, where A is either $N2$, $CO2$, $H2O$, $NH3$, or $H2$, or $H2$, while B are either rare gas atoms (Rg = He, Ne, Ar) or $H2$. Rotationally-resolved spectra of the dimers (n=1) provide information about the intermolecular potential (equilibrium geometry, binding energy, effects of tunneling and internal rotation). For larger clusters ($n-1$), frequency shifts in vibrational spectra give rise to a consistent picture of cluster growth (microsolvation process). Recent results for $Nen\dots HCO+$ (n=1.2) will be compared to those for the previously characterized $Arn\dots HCO+$ series (n=1.13).