Delayed photodissociation of the tin cluster Sn 22 .

Millisecond-delayed photodissociation of gas-phase Sn 22 - clusters stored in a Penning trap is investigated as a function of excitation energy. Sn 15 - is the only significant charged fragment, indicative of the break-off of neutral heptamers. Fits of the time-resolved fragmentation require a distribution of decay constants, caused by the finite width of the internal energy distribution of the cluster ensemble prior to photoexcitation. A lower limit for the dissociation energy for the loss of Sn 7 is determined to be 2.1(1) eV, a factor of two above literature quantum chemical calculations.