Dewetting process induced by a nanosecond laserpulse imping on Au-triangles on graphit. The energy density increases from upper left to lower right.

Thin metallic films are typically not stable on oxide surfaces. Thus upon increasing the temperature dewetting will start which finally leads to individual nanoparticles. We study such dewetting processes after a temperature increase induced by a nanosecond laser pulse.

Upon illumination of individual nanostructures (e.g. triangles) with pulsed light the material will melt at a material-dependent threshold energy density. Immediately after melting, the liquid has a contact angle far from equilibrium and thus surface tension rearranges the liquid towards the equilibrium contact angle, which is close to a sphere. This transformation process (flat molten nanostructure towards liquid sphere) which can be seen in the image below happens on a timescale of few nanoseconds. As one can already suspect from the image this transformation is accompanied by an upward-movement of the center of mass. This leads to the jumping of the nanodroplets off the surface with velocities in the range of tens of m/s.