Decrypting the charge-resolved kinetic-energy spectrum in the Coulomb explosion of argon clusters

Abstract

Ion emissions from clusters in intense ultrashort laser fields have been studied predominantly using Time-Of-Flight (TOF) spectroscopy so far. Assuming atomic ion emission, arrival time signal is converted to a charge-integrated kinetic-energy spectrum. We present here a Thomson parabola spectrum that decrypts the charge-integrated energy distribution to the Charge-Resolved Kinetic-Energy Spectra (CRKES). TOF measurements compare well with the spectrum generated by encrypting back the CRKES. A quantitative measure of ionization probabilities of Ar₃₆₀₀₀ clusters to varied charge states at 7 × 10¹⁵ W cm⁻² is compared with three-dimensional microscopic particle-in-cell simulations. A good agreement between these detailed measurements and the simulations shows the possibility for the retrieval of charge distribution within a nanocluster.