Fission of multiply charged alkaline earth metal clusters

We have studied the fission of multiply photoionized alkaline earth metal clusters having charges up to Z = +5 by means of high-resolution time-of-flight mass spectrometry. The determined appearance sizes can be compared to results of simple model calculations assuming that both fragments can still be treated as metallic liquid droplets. In this case the measured appearance sizes for the alkaline earth metals are found to be smaller than the ones predicted by the calculations. However, if one fixes the small fragment to be an atomic ion, good agreement between measurement and theory is acheived.