YO A(2)PI(1 2,3/2) VIBRATIONAL-STATE DISTRIBUTIONS MEASURED AFTER THEEXCIMER-LASER ABLATION OF Y2O3 USING A LASER-INITIATED PULSED DISCHARGE AS A PROBE/

The vibrational populations of the YO A2PI-X2SIGMA system of YO were m easured in the plasmas generated after the excimer laser ablation of Y 2O3 in oxygen when both continuous and pulsed electric fields were app lied. When an electric field is applied antiparallel to the direction of propagation of the ejected electrons, two luminous plumes appear, s eparated by several microseconds. The measured vibrational populations of the YO A2PI-X2SIGMA system are different for each plume. The YO A2 PI populations were nonthermal in the first plume, representing emissi on from chemiluminescent reactive collisions in the plume after ablati on. The second emission pulse, initiated by the discharge of a high-vo ltage capacitor, probes the ground-state YO in the plume via electron collisions. This pulsed electric field holds promise as a diagnostic p robe of the ground-state species emitted in laser ablative processes.