Berlin 2012 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 2: Computational Materials Modelling I - Multiscale: Fundamentals

MM 2.4: Talk

Monday, March 26, 2012, 11:00–11:15, TC 006

Molecular Dynamics Simulations of Laser Ablation in Metals: Parmeter Dependence, Double Pulses, and Extended Models — •Johannes Roth, Johannes Karlin, Marc Sartison, Armin Krauss, and Hans-Rainer Trebin — ITAP, Universität Stuttgart

Femtosecond laser ablation of metals depends on three parameters: electron heat conductivity, electron heat capacity and electron-phonon coupling. With respect to these parameters all metals can be devided into classes. Keeping the interaction and the crystal structure fixed we have varied the parameters within the experimentally observed range. We find that the heat capacity plays a minor role whereas the other parameters are equally important.

In a second part we have studied the melting behavior and ablation properties of Al under the influence of non-Gaussian and double pulses at a certain time interval. In general we find that a simple Gaussian pulse is the most effective method to ablate material.

The ablation by femtosecond laser pulses is a process dominated by the free electrons of the metal. To model the process correctly, one uses the two-temperature-model (TTM) with separete temperatures for the electrons and the lattice. The model still neglects a finite electron relaxation which is treated in an extended TTM. We show numerically and by simulations that the simple TTM leads to satisfactory results for Al and Nb, but that the extended TTM should be applied for example for Cu or Pb.