Laser-induced Coulomb explosion in C and Si nanoclusters: The determining role of pulse duration

We investigate, at the quantum-mechanical level, the interaction of ultrashort laser pulses with small (less than ∼4 nm) carbon and silicon nanoclusters. We find that the outer-ionization mechanism—by virtue of which electrons are ejected from the outer shells of the clusters—goes through a peak for very short (fs) pulses, whose position depends exclusively on the duration of the pulse while other parameters, such as laser fluence and cluster size, only affect its intensity. Our results thus establish that Coulomb explosion, an important process for the disintegration of materials under intense laser pulses, is almost entirely determined by the duration of the pulse while other “experimental” parameters have relatively modest effects.