Electron Release of Rare-Gas Atomic Clusters under an Intense Laser Pulse

Calculating the energy absorption of atomic clusters as a function of the laser pulse length T we find a maximum for a critical T^*. We show that T^* can be linked to an optimal cluster radius R^*. The existence of this radius can be attributed to the enhanced ionization mechanism originally discovered for diatomic molecules. Our findings indicate that enhanced ionization should be operative for a wide class of rare-gas clusters. From a simple Coulomb-explosion ansatz, we derive an analytical expression relating the maximum energy release to a suitably scaled expansion time which can be expressed with the pulse length T^*.