  We investigated femtosecond laser ablation dynamics using THz time-domain
spectroscopy. To clarify the breakdown dynamics of materials, we focused on the
motion of charged particles and measured the terahertz waves emitted during
laser ablation. We revealed that the Coulomb force dominated the ablation
process. Furthermore, comparisons of the experimental results with theoretical
models showed that material breakdown occurs within a few hundred femtoseconds.
Our experimental results indicate that electrostatic ablation is the most
likely ablation mechanism for metals.
