GAS-PHASE REACTIONS DURING REACTIVE LASER-ABLATION OF TI AND SI IN N-2 AND O-2 RAREFIED ATMOSPHERES ANALYZED USING ENERGY-DISPERSIVE MASS-SPECTROMETRY

We have utilised energy-dispersive mass spectrometry to investigate th e energy and composition of ionic products formed during the pulsed la ser ablation of Ti and Si targets. Specifically, we have observed the evolution of molecular ion species in backgrounds of O-2 and N-2 over a wide range of pressures (10(-7)-10(-1) mbar). The yields of these sp ecies are significantly dependent upon the background gas pressure and , therefore, number density of the background species and the implied collisional frequency. We propose an interpretation of the relative yi elds of the species based upon their gas-phase binding energies and re action cross-sections.