Mechanism Of Femtosecond Laser Ablation Of Metal Target Under Liquid Environment

The interaction between femtosecond laser and material produces a lot of marvelous phenomenas which have received a great deal of researcher's attention.Target surface will be ablated when have been radiated by femtosecond pulse laser with nearby material ablation threshold, then produce ananoparticles. Nanoparticles'size is related with energy density, pulse width and wave length of laser and so on, But it is not easy to control nanoparticles'size and nanoparticles easy to be aggregated when preparaed in the gas environment, moreover requested the quite high experiental condition, therefore nanoparticles'peparation of laser ablation under the liquid environment becomes a hot spot that people studied. However it is not clear mechanism of femtosecond laser ablation under the liquid environment and how the liquid to influnce the laser ablation,therefore the further studies of liquid ablation's influence and mechanism of the femtosecond laser ablation is helpful to provide the theory support for preparing better nanoparticles.This article first summarized the new characteristic of femtosecond laser, the femtosecond laser'sapplication as well as the development of preparing nanoparticles by the femtosecond laser ablation, the research survey of interaction between femtosecond laser and the material, the femtosecond laser technology's development under the liquid environment,displays research present situation of preparing nanoparticles by the femtosecond laser ablation under liquid environmentNext we introduced the theoretical models of interaction mechanism between femtosecond laser and metal, and established revision Two-Temperature Mode model which descriped the femtosecond laser ablation metallic material under liquid environment with the classics Two-Temperature Model's foundation. Take the copper target for example, the process has carried on the numerical simulation femtosecond laser ablation metal target material's dynamics in the water, and discussed the electron and the lattice temperature which evolved along with the time in the different water's depth and how water's depth and laser energy density to influence femtosecond laser ablation metal target in preparing nanoparticles.The result indicated: The water's depth is deeper, the laser energy losses more, the electron-phonon coupling time is shorter, is more advantageous in preparing the small size nanoparticles; The laser energy density is bigger, the electron-phonon coupling time is longer, does not favor preparing small size nanoparticles. Because the water's absorption characteristic for the laser, must choose the reasonable values of water's depth and the laser energy density in the experiment, then can have the ablation and produces nanoparticles.Revision Two-Temperature Model explains well water film metal target material dynamics process through research femtosecond laser ablation metal target under liquid environment, not only can explain reasonablely the influence of water's depth to ablation,but also explains the energy density influence the ablation,and it provides a theory instruction for preparing the high quality nanoparticles...