Study of various material particles by third harmonic generation method based on laser pulse induced plasma

摘要： Third harmonic generation (THG) from plasma can be used as probe radiation to characterize the plasma components. In this work, we present the study of the spatiotemporal profile of generated particles in various plasmas produced from bulk targets (C, Cr, In, Ni, Ag, CdS and ZnS) using pulsed laser ablation and THG using 800 nm, 40 fs probe pulses. The dependence of THG on the probe pulse intensity and the distance of the probe beam from the target position are analyzed. The influence of the ejected particle mass on THG with respect to the distance between the target and the probe pulses position was observed. The temporal evolution of THG depended on the delay between heating 6 ns pulses and driving 40 fs pulses. The variation of third harmonic intensity in the plasma components with atomic weight M on the delay (td) was consistent with the kinetic model described by relation td ∞ M0.5. THG from metal targets was mostly originated from the atomic and ionic components in plasma, whereas the clusters and heavier particles were responsible for this process in the case of ablated semiconductor materials.