Comparison of Pd plasmas produced at 532 nm and 1064 nm by a Nd:YAG laser ablation

A comparison between the laser ablation of a palladium target in vacuum, by using 1064 nm and 532 nm Nd:YAG laser wavelengths, with an intensity of about 10(9) W/cm(2), is reported. Nanosecond pulsed ablation produces high non-isotropic emission of neutrals and ions. For both wavelengths, mass quadrupole spectrometry and time-of-flight measurements allow estimation of the atomic and ionic species emitted from the plasma and of their energy distributions. Ions show Coulomb-Boltzmann-shifted distributions depending on their charge state. Surface profiles of the ablated craters permitted to study the ablation threshold and yields of palladium in vacuum vs. the laser fluence. The plasma temperature and density was evaluated by the experimental data. A special regard is given to the ion acceleration process occurring inside the plasma, due to the high electrical field generated inside the plasma. (c) 2010 Elsevier B.V. All rights reserved.