TIME-RESOLVED ABSORPTION STUDIES OF EXCIMER-LASER ABLATION OF CAF2

Time-resolved optical absorption spectroscopy has been used to determi ne the particle densities of Ca, Ca+, Ca and relative densities of Ca F molecules produced by KrF-laser ablation of CaF2 in air. The time-re solved spectra show a very strong broadening of the absorption lines a t short delay times near the surface. The broadening mechanism has bee n discussed. The spatial and temporal behaviour of the particles in th e ablation plume near the surface was found to be strongly affected by both the air atmosphere and the reaction dynamics in the plasma zone.