Shengfu Yang,* Daniel Spence, Elspeth Latimer, Cheng Feng,
Department of Chemistry, University of Leicester, LE1 7RH, United Kingdom
Superfluid helium nanodroplets are emerging as a versatile tool for the synthesis of novel nanoparticles. Here we report our recent discovery of quantized vortices in helium droplets  and usage of vortices to fabricate one-dimensional nanostructures. To demonstrate we have synthesized Ni, Cr, Au and Si nanowires by this means, which generally shows a very small diameter (4- 6 nm) and the lengths can be up to several microns (see Figure 1 for the TEM images of ultrathin Ni nanowires).
Unlike other synthetic techniques where a directing agent is often needed to form nanowires, no extra constraint is needed for the formation of ultrathin nanowires using the vortices in helium droplets. In addition, the sequential pickup of different types of materials following the geometric pickup order allows different types of materials being independently controlled and added to helium droplets. This therefore circumvents the major difficulty in the fabrication of binary nanowires using conventional approaches, where simultaneous control on the growth rates of different types of materials is crucial but in many case is unable to be achieved.
- Yang, S.; Ellis, A. M.; Spence, D.; Feng, C.; Boatwright, A.; Latimer, E.; Binns, C. Nanoscale 5 (2013) 11545-11553.
- Spence, D.; Latimer, E.; Feng, C.; Boatwright, A.; Ellis, A. M.; Yang, S.; Phys. Chem. Chem. Phys. 16 (2014) 6903-6906.
- Latimer, E.; Spence, D.; Feng, C.; Boatwright, A.; Ellis, A. M.; Yang, S.; Nano Lett. (2014) in press.