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 Ar${}_{36\phantom{\rule{0.16em}{0ex}}000}$ clusters to varied charge states at $7\ifmmode\times\else\texttimes\fi{}{10}^{15}$ W cm${}^{\ensuremath{-}2}$ 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.