Characteristics of laser-induced plasma from highT c superconductor

Abstract

AiJsIract. The spectroscopic analysis of the emission from the plasma produced by irradiating a high T, superconducting GdBa z Cu)07 target with a high power Nd: Y AG laser beam shows the existence of the bands from dilTerent oxides in addition to the lines from neutrals and ions of the constituent elements. The spectral emissions by oxide species in laser-induced plasma show considerable time delays as compared to those from neutral and ionic species. Recombination processes taking place during the cooling of the hot plasma.rather than the plasma expansion velocities, have been found to be responsible for the observed time delays in this case. The decays of emission intensities from various species are found to be non-exponential.

Spatial and temporal analysis of laser induced plasma from a polymer sample

“…From the time delays observed, in the case of higher laser energies, it can be safely concluded that the molecular bands are mainly formed when the plasma temperature begins to fall. This lends support to the view that the molecular speciesmaynot beoriginatingfrom the target materialat higher laser powers, but are formed as a result of recombination processes as the hot plasma cools down [21],i.e. themolecularspeciesareformedintheexpanding plasma due to collisions of the atomic and ionic species expelled from the target surface.…”

“…In order to study the time evolution of a particular species produced by laser ablation, the characteristic lines were selected using the monochromator, and the PMT output terminated at 50 R resistance, was fed to a 100 MHz storage oscilloscope (Tektronix Model 466) (figure 3) [21]. Typical oscilloscope (CRO) traces of the PMT response to the emission from the C2 species in the three different regions (A, B and C) of the plasma plume are shown in figures 4(a), ( b ) and (c) respectively.…”