Femtosecond pulsed laser ablation of group 4 carbides

The pulsed laser ablation of titanium, zirconium and hafnium carbides has been performed by a Nd:glass laser with a pulse duration of 250 fs. The gaseous phase produced from the ablation has been analysed by emission spectroscopy and ICCD imaging. The results evidence large differences in the plasma characteristics in the case of femtosecond or nanosecond ablation. In particular, in the femtosecond and nanosecond plumes, the energy and the velocity of neutral and ionised particles are very different. The ablation mechanism seems to be very different, including, in the case of femtosecond ablation, the delayed emission from the target of large and slow particles. The morphology of the deposited films is clearly related to the characteristics of the plasma. Preliminary results show a morphology consisting of a large number of spherical particles with diameters ranging from 50 to 200 nm.