@article{25355, keywords = {model, particle, particles, lead, transformation, usa, surface, power, films, ablation, laser, laser ablation, laser-ablation, time-resolved, state, time, ca, e, liquid, sample, c, crater, volume, nanosecond, metal, nanosecond laser, depth, silicon, layer, threshold, generation, particulates, irradiance, circulation, phase explosion, phase-explosion, physics, single-crystal, dielectric, thickness, transparency, critical state, critical-state, deep, ejection}, author = {Jong-Hyun Yoo and Sungho Jeong and Xianglei Mao and Ralph Greif and Richard E Russo}, title = {Evidence for phase-explosion and generation of large particles during high power nanosecond laser ablation of silicon}, abstract = {

The craters resulting from high-irradiance (1×109–1×1011 W/cm2) single-pulse laser ablation of single-crystal silicon show a dramatic increase in volume at a threshold irradiance of 2.2×1010 W/cm2. Time-resolved shadowgraph images show ejection of large particulates from the sample above this threshold irradiance, with a time delay ∼300 ns. A numerical model was used to estimate the thickness of a superheated layer near the critical state. Considering the transformation of liquid metal into liquid dielectric near the critical state (i.e., induced transparency), the calculated thickness of the superheated layer at a delay time of 200–300 ns agreed with the measured crater depths. This agreement suggests that induced transparency promotes the formation of a deep superheated layer, and explosive boiling within this layer leads to particulate ejection from the sample.

}, year = {2000}, journal = {Applied Physics Letters}, volume = {76}, pages = {783-785}, month = {02/2000}, doi = {10.1063/1.125894}, note = {

LBNL-44782 NOT IN FILE

}, language = {eng}, }