Direct generation of core/shell nanoparticles from double-pulse laser ablation in a background gas

In this study, a double-pulse laser ablation scheme is proposed to generate core/shell nanoparticles (CS-NPs). Compared with other existing methods for the generation of CS-NPs, the new scheme figures with its simple and in situ approach and can be applied to a wider variety of materials. Several types of CS-NPs are successfully generated with this new scheme (i.e. Sn/glass, Zn/glass, Zn/Si, Ge/Si, Cu/Zn CS-NPs). Four key factors affecting the generation of CS-NPs with this new scheme are also examined, namely (a) surface tensions of materials constructing the CS-NPs and its Gibbs free energy, (b) contribution of background gases (He and Ar), (c) contribution of the delay time between two lasers pulses and (d) contribution of laser energy on the formation of CS-NPs.