Size-Selective Optical Printing of Silicon Nanoparticles through Their Dipolar Magnetic Resonance

TL;DR

This paper presents a novel optical printing method for size-selectively immobilizing silicon nanoparticles on substrates by exploiting their magnetic dipolar resonances, enabling precise placement based on size-dependent optical forces.

Contribution

The study introduces a surfactant-free optical printing technique that sorts silicon nanoparticles by size using wavelength-tuned magnetic resonances, advancing nanoparticle organization methods.

Findings

Size-selective immobilization of silicon nanoparticles achieved.

Optical forces tuned to magnetic resonances enable precise sorting.

Nanoparticles of narrow size distribution can be organized on substrates.

Abstract

Silicon nanoparticles possess unique size-dependent optical properties due to their strong electric and magnetic resonances in the visible range. However, their widespread application has been limited, in comparison to other (e.g. metallic) nanoparticles, because their preparation on monodisperse colloids remains challenging. Exploiting the unique properties of Si nanoparticles in nano- and micro-devices calls for methods able to sort and organize them from a colloidal suspension onto specific positions of solid substrates with nanometric precision. Here, we demonstrate that surfactant-free Silicon nanoparticles of a predefined and narrow ($\sigma$ < 10 nm) size range can be selectively immobilized on a substrate by optical printing from a polydisperse colloidal suspension. The size selectivity is based on differential optical forces that can be applied on nanoparticles of different sizes by tuning the light wavelength to the size-dependent magnetic dipolar resonance of the nanoparticles.