Flow Dynamics of Ions Generated by Laser-Blow-Off of LiF-C Film

The flow dynamics of ejected ions generated by the laser-blow-off of a multicomponent LiF-C thin film deposited on a quartz substrate has been studied using the charge collector probe technique. The spatial distributions of ions were analyzed in different ambient environments ranging from high vacuum to 0.2 mbar of argon pressure and at various laser fluences varying from 2.8 to 26 J/cm
²
. In vacuum, a double peak structure was observed in the temporal profile of the ion signal at low laser fluence, which slowly transformed into a single peak with increasing laser fluence. The observed plume splitting in vacuum as well as in background gas is interpreted by the formation of ions by two different mechanisms that can produce two different velocity distributions. Present findings at a large collector to target distance, d = 70 mm was found to be consistent with our previously reported optical emission spectroscopic results at a relatively small distance (d = 12 mm).