Dry launching of silica nanoparticles in vacuum

TL;DR

This paper introduces a simple, cost-effective dry launching method for silica nanoparticles in vacuum, enabling precise loading into optical traps for optomechanics experiments.

Contribution

The study presents a novel dry launching technique using PTFE surface shaking, achieving successful loading of silica nanoparticles as small as 43 nm radius into optical traps.

Findings

Successful launching of 43 nm radius silica nanoparticles

High flux and small angular spread (~±10°) of launched particles

Velocities below 1 m/s enabling effective trapping

Abstract

Clean loading of silica nanoparticles with a radius as small as ~50 nm is required for experiments in levitated optomechanics that operate in ultra-high vacuum. We present a cheap and simple experimental method for dry launching of silica nanoparticles by shaking from a polytetrafluoroethylene (PTFE) surface. We report on the successful launching of single silica nanoparticles with a minimum radius of 43 nm, which is enabled by the low stiction to the launching surface. Nanoparticles with radii of 43 nm and 71.5 nm are launched with a high flux and small angular spread of $\sim \pm 10^\circ$, which allows for trapping in a tightly focused optical tweezer within a couple of minutes. The measured velocities are significantly smaller than 1 m/s. The demonstrated launching method allows for controlled loading of dry nanoparticles with radii as small as 43 nm into optical traps in (ultra-)high vacuum, although we anticipate that loading of smaller sizes is equally feasible.