  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.
