Photochemistry in rare gas clusters

In this contribution photochemical processes in pure rare gas clusters will be discussed. The relaxation dynamics of electronically excited He cluster s is investigated with luminescence spectroscopy. After electronic excitati on of He clusters many sharp lines are observed in the visible and infrared spectral range which can be attributed to He atoms and molecules desorbing from the cluster. It turns out that the desorption of electronically excit ed He atoms and molecules is an important decay channel. The findings for H e clusters are compared with results for Ar clusters. While desorption of e lectronically excited He atoms is observed for all clusters containing up t o several thousand atoms a corresponding process in Ar clusters is only obs erved for very small clusters (N < 10).