Hotter electron generation in doped clusters

Abstract

We present electron energy measurements from nano-cluster plasmas that are formed when molecule-doped rare-gas clusters are irradiated by intense, 100 fs laser pulses of intensity ∼10¹⁵ W cm⁻². In pure Ar clusters the high temperature component (energy ∼1400 eV) is less than 1% of the low temperature component (energy ∼130 eV), while for water-doped Ar clusters the high temperature component is as high as 7% of the low temperature component. Numerical estimates based on collisional ionization and inverse bremsstrahlung absorption indicate that the easily ionizable dopant molecules enhance the propensity for ionization ignition by significantly altering the temporal profile of the inner-ionized electron density within the cluster.