Pulsed laser ignition of reactive multilayer films

Nanostructured Al/Pt multilayer films were ignited by single pulse irradiation from a Ti:sapphire femtosecond laser system. Critical ignition fluences (0.9-22 J/cm(2)) required to initiate a self-propagating reaction were quantified for different multilayer designs. Multilayers with smaller bilayer thickness required relatively lower fluence for ignition. Ignition threshold fluence was also found to be 1.4-3.6 times higher for Al-capped multilayers than for Pt-capped multilayers. Ablation threshold fluences were measured for Al (860 +/- 70 mJ/cm(2)) and Pt (540 +/- 50 mJ/cm(2)) and related to the observed difference in ignition fluences for Al- and Pt-capped multilayers. (c) 2006 American Institute of Physics.