Solitary Nanostructures Produced by Ultrashort Laser Pulse
Autor: | Vasily Zhakhovsky, K. P. Migdal, Yury Petrov, Nail Inogamov, Viktor Khokhlov |
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Rok vydání: | 2015 |
Předmět: |
Formation of microbump
79.20.Eb Materials science Capillary action Nanochemistry 02 engineering and technology Substrate (electronics) 02.70.Ns Molecular dynamics 01 natural sciences Fluence law.invention Condensed Matter::Materials Science Optics Materials Science(all) law 0103 physical sciences Thin film on substrate General Materials Science 010306 general physics Jet (fluid) Nano Express 62.50.Ef business.industry Conical surface 021001 nanoscience & nanotechnology Laser Condensed Matter Physics Ultrashort laser pulse Pulse (physics) PACS Codes 0210 nano-technology business |
Zdroj: | Nanoscale Research Letters |
ISSN: | 1931-7573 |
Popis: | Laser-produced surface nanostructures show considerable promise for many applications while fundamental questions concerning the corresponding mechanisms of structuring are still debated. Here, we present a simple physical model describing those mechanisms happened in a thin metal film on dielectric substrate irradiated by a tightly focused ultrashort laser pulse. The main ingredients included into the model are (i) the film–substrate hydrodynamic interaction, melting and separation of the film from substrate with velocity increasing with increase of absorbed fluence; (ii) the capillary forces decelerating expansion of the expanding flying film; and (iii) rapid freezing into a solid state if the rate of solidification is comparable or larger than hydrodynamic velocities. The developed model and performed simulations explain appearance of microbump inside the focal spot on the film surface. The model follows experimental findings about gradual transformation of the bump from small parabolic to a conical shape and to the bump with a jet on its tip with increasing fluence. Disruption of the bump as a result of thinning down the liquid film to a few interatomic distances or due to mechanical break-off of solid film is described together with the jetting and formation of one or many droplets. Developed theory opens door for optimizing laser parameters for intended nanostructuring in applications. |
Databáze: | OpenAIRE |
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