High-temperature explosion of atomic clusters irradiated by a sequence of two high-intensity laser pulses

Summary form only given. We have investigated the possibility of using two pulses with different frequencies to excite the resonance in the heating twice during the expansion of the cluster, thereby enhancing the electron heating. The numerical model has been adapted to simulate the irradiation of a cluster with a sequence of laser pulses of the same or different frequencies. The results of this new model support the idea that using two pulses of different frequencies will strongly affect the measured electron energy distributions. An enhancement in hot electron production is predicted under some conditions. We have also performed experimental investigations of the dynamics of clusters of a few thousand Xe atoms when irradiated by two laser pulses of 780 nm and 390 nm. Both ion and electron energy distributions have been obtained, and the effects of changing the relative delays, intensities, and polarizations of the two pulses have been studied. The results have been compared with the energy distributions obtained when the clusters are irradiated with just one pulse at 780 nm or 390 nm, or with two pulses of the same color. The comparison of the experimental results with the numerical simulations provides a sensitive test of the model and has helped to further elucidate the mechanism of the superheating of clusters in intense laser fields.