Energy-dispersive mass spectrometry of high energy ions generated during KrF excimer and frequency-doubled Nd:YAG laser ablation of metals

The accurate measurement of high energy ions (up to 500 eV) produced during the laser ablation process has been investigated using energy-dispersive mass spectrometry. A comparison between 5 J cm−2 ablation of metals, such as Cu and Fe, by 532 nm Nd:YAG and 248 nm excimer laser irradiation shows the effect of pulse duration on the kinetic energy distributions of the generated ions. The propagation of Fe+ ions within the laser produced plasma through high vacuum shows significant modification due to ion acceleration processes with increasing distance from the target. Significantly, no attenuation of detected signal is observed with increased target-spectrometer distance, thus indicating a highly forward-peaked distribution of high energy ions.