The Acoustic Characteristics of a Coulomb Explosion Resulting from Single Femtosecond Laser Pulse Ablation of Metals
D. Zhong, Z-M. Li, R-L. Ruan and L-Y. Liu
We report the first direct observation of Coulomb explosion as the result of the single femtosecond pulse laser ablating metal materials by using optical fibre sensor probe. The acoustic characteristic of the expansive microplasma has been analysed. The results show that different pure metals have their own characteristic acoustic frequency for the single microplasma explosion wave of the metals ablated by the femtosecond laser under the same measuring condition, meanwhile the acoustic frequency of a metal material keeps the same for different ablation energies, which are related to the crystal structure of the material. The acoustic features of single Coulomb explosion not only directly indicate the ablation mechanism of metal materials, but also can be used to detect the metal material components.
Keywords: Femtosecond laser, Ti:Sapphire laser, metal, aluminium, Al, copper, Cu, iron, Fe, Coulomb explosion, microplasma, ablation, single pulse, acoustic characteristic