Thermal tweezers for nano-manipulation and trapping of interacting atoms or nanoparticles on crystalline surfaces.

Thermal tweezers is an all-optical nanofabrication technique where surface thermophoresis due to holographically induced strong temperature modulation is used for parallel manipulation and trapping of adatoms and adparticles with nanoscale resolution. This paper conducts the detailed numerical analysis of thermal tweezers in the presence of significant interaction between the adparticles on the surface. In particular, we demonstrate that the considered inter-particle interactions result in a significant enhancement of the surface thermophoretic effect and substantially increases modulation of particle concentration on the surface. In addition, we predict the possibility to achieve adparticle confinement on the surface to strongly sub-wavelength regions ∼12 times smaller than the vacuum wavelength of the optical radiation. A numerical approach to surface diffusion of interacting nanoparticles and adatoms is developed, the Monte Carlo interaction method, and its applicability conditions and limitations are discussed. The obtained results will be important for better understanding of the fundamental aspects of surface thermophoresis, as well as the development of new approaches to nano-patterning of surfaces for engineering their optical, electronic, chemical, and mechanical properties by means of the directed self-assembly of nanoparticles and adatoms.