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Reaction Pathways of a Regular Disintegration of Nanowires by Thermocapillarity
Röntzsch, L.; Heinig, K.-H.;
Surface free energy minimization driven by capillary forces leads to morphological changes of wires, e.g. disintegration into a droplet chain – known as Rayleigh instability. At the nano-scale, capillary effects are much more pronounced than in macroscopic systems due to the large surface-to-volume ratio. However, capillary-driven self-organization processes are subject to increasing fluctuations with decreasing dimensions, which mostly prevent the formation of regular structures with long-range order. In this contribution, we predict by means of kinetic Monte Carlo simulations a novel method to fabricate size-controlled chains of nanodroplets. Our prediction rests on the temperature dependence of surface tension – the origin of thermocapillarity. Uncompensated forces occur due to surface temperature gradients. These forces lead to material transport and structure formation on short time and length scales. A surface tension gradient triggers the biased migration of atoms from hot to cold regions by surface diffusion. A periodic temperature gradient along a nanowire might be achieved by a surface-plasmon-polariton (SPP) wave. For SPP excitations with long wavelengths (e.g. by a CO2 laser), sufficiently strong steady-state temperature gradients may be produced. However, pulsed operation might be necessary for shorter wavelengths. We predict that the regularity of nanodroplet chains, that form during a self-organized disintegration of nanowires, might be considerably improved by SPPs. If the SPP wavelength is commensurable with the inherent Rayleigh wavelength of the nanowire disintegration, the SPP-induced temperature undulations control the Rayleigh instability. Thus, a regular and long-range order in nanodroplet size and position may be achieved.
Keywords: Rayleigh instability, nanowire, thermocapillarity, disintegration, long-range order
  • Poster
    DPG Frühjahrtagung 2006, 26.-31.03.2006, Dresden, Deutschland

Publ.-Id: 8367 - Permalink