Radiative Cooling of a Small Metal Cluster: The Case of $V_{13}^{+}$

Size-selected stored metal cluster ions, ${\mathrm{V}}_{13}^{+}$, have been heated by photoexcitation ( $\lambda =730\mathrm{}$ to 229 nm) to well-defined excitation energies corresponding to temperatures between 1000 and 2100 K. A millisecond pump-probe photodissociation technique was applied to measure the time-resolved radiative cooling. The observed decay rates are directly related to the radiative energy loss and are explained quantitatively by the competing processes of photoemission and atom evaporation.