Laser polymer ablation threshold lowered by nanometer hot spots

The effects of nanometer-sized hot spots on laser polymer ablation are studied. Two polymer thin films are synthesized, containing sensitizers which absorb intense 1.064 μm optical pulses. One film contains a molecular dye sensitizer. The other contains graphic nanoparticle sensitizers (≤220 nm diam). When longer duration pulses (150 ns) which do not produce hot spots are used, both films have the same ablation threshold. When shorter (23 ps) pulses are used, the ablation threshold for graphite films is a factor of 3 less than in dye films, attributed to enhanced polymer thermal decomposition in the vicinity of the larger graphite hot spot.