Gold ions produced by 1064 nm pulsed laser irradiation

A Nd:Yag laser, 9 ns pulse width and 900 mJ maximum energy, is employed to irradiate gold targets in vacuum. Using a laser fluence higher than 15 J/cm (2), the irradiation produces a plasma formation in front of the target wit h a plume directed along the normal to the laser spot surface. On line meas urements have been obtained with a quadrupole mass spectrometer, with a tim e of flight technique and with an energy-to-charge ratio ion analyzer. Resu lts demonstrate that the threshold fluence for neutral and ion emission is practically the same. Moreover, ions at different charge state are produced with an energy spectrum from hundreds of eV up to some keV. (C) 2001 Elsev ier Science B.V. All rights reserved.