STUDIES OF THE FORMATION OF CLUSTER IONS NH4+CENTER-DOT(NH3)(N),N=1-4, USING A HIGH-PRESSURE FLOWING AFTERGLOW APPARATUS

A new high pressure flowing afterglow apparatus with an operational pressure range of 1-20 Torr is described. The new technique has been applied in a room temperature study on the kinetics of the clustering reactions NH4+.(NH3)(n) + NH3 reversible arrow NH4+.(NH3)(n+1) for n = 0-3. The equilibrium constants and the corresponding changes in standard Gibbs free energy (Delta G(p)(o)) for these reactions were derived: Delta(01)G(p)(o) = -11.2 kcal mol(-1), Delta(12)G(p)(o) = -9.3 kcal mol(-1), Delta(23)G(p)(o) = -7.0 kcal mol(-1), Delta(34)G(p)(o) = -4.6 kcal mol(-1), where the indices indicate the number of molecules of NH3 attached to NH4+ before and after association.