Absolute separation energies for Na clusters

Na clusters in the size range of 50-400 atoms are led to evaporate in a heat bath with controlled temperature. For cluster sizes around closed shells, decay rates are determined as a function of temperature. For temperatures below 357 K they all agree with an Arrhenius law and allow absolute separation energies to be extracted. Separation energies are presented and compared to previously determined (relative) values. Enhanced shell effects are observed in the heat bath experiments. Deviations from the Arrhenius law at intermediate temperatures are discussed.