Impurities good and bad: doped cluster nanoplasmas in intense laser fields and characterization of impurity level

Abstract

Doping of cluster-based targets can bring out considerable modifications in the evolution of the nanoplasma formed from clusters in intense laser fields. The consequence could be either an increase or a decrease (depending upon the properties and proportion of the dopant) in the emission of the resulting charge particles or photons from nanoplasma. As we can control the percentage of CS₂ in the doped Ar-CS₂ cluster, we can have argon-doped CS₂ cluster (when argon constitutes about 10–40 %) and CS₂-doped argon cluster (when fraction of CS₂ is 10–40 %). In the experimental studies of electron spectra and X-ray emission from pristine Ar_n (n≤ 25, 000) and doped Ar-CS₂ clusters at laser intensities of about 10¹⁵ W cm⁻², it is observed that there is more than an order of magnitude enhancement in those emissions in doped Ar-CS₂ clusters than in the former case. Conversely, a significant reduction in those emissions was found in the latter case. Such observations signify the importance of characterization of these targets. In this direction, we demonstrate a simple method for the characterization of doping level based on the Rayleigh scattering measurements.