Berlin 2008 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 5: Nanostructured Materials II

MM 5.3: Talk

Monday, February 25, 2008, 12:30–12:45, H 0107

Modeling of Surface Modification and Nanostructuring on Metals due to a Femtosecond Laser Pulse — •Dmitriy Ivanov¹, Baerbel Rethfeld¹, Gerard O'Connor², Thomas Glynn², Zhibin Lin³, and Leonid Zhigilei³ — ¹Physics Department, Technical University of Kaiserslautern, Kaiserslautern, Germany — ²National Centre for Laser Applications, National University of Ireland Galway, Galway, Ireland — ³Materials Science Department, Univeristy of Virginia, Charlottesville, USA

The atomistic-continuum approach to study nanostructuring processes on metals due to fast laser energy deposition is presented. The intense, short-pulsed laser interactions are involving mechanical, thermal, and phase perturbations. Many of those non-equilibrium processes are impossible to study experimentally and difficult to model at all levels: ab-initio, atomistic, and continuum. We address this challenge combining the advantages of different approaches. Namely, the kinetics of fast non equilibrium phase transformations is treated at atomic level; and free carrier dynamics (fast electron heat conduction and laser-induced electron-phonon nonequilibrium)is accounted for in continuum part.

The combined model was applied to study the formation of nanojets on thin Ni films in femtosecond laser pulse experiments. The calculations show that surface nanostructuring is due to the interplay of three processes: establishment of temperature gradient in radial directions causes the elasto-plastic deformations; relaxation of laser-induced pressure leads to the ejection of melted material; fast electron heat conduction in 3D effectively cools down and freezes the ejected matter.