Observation of species distribution in laser induced plasma

The species distribution and evolution in laser induced plasma are optically studied by using time-of-flight spectra extracted from time-resolved spectra and newly introduced space-of-flight spectra extracted from space-resolved spectra. The plasma consists many ionic and atomic species. At the head of the plasma plume, ions an always the dominant species. However, there are two distribution peaks for the atoms. One is at the head, and another is at the tail of the plume. If the laser fluence used is high enough, the atoms reside mainly in the tail of the plume. The distribution changes with time and space, which implies an evolution of the species in the course of plasma flying. It is also observed that the proportion of ions to atoms in the plasma decreases with decreasing laser fluence. (C) 2000 Elsevier Science B.V. All rights reserved.