 Solution

Prepare a dilute dispersion of separated nanoparticles on an electron-transparent support, for example a thin carbon film on an electron-microscopy grid. A sparse deposited aliquot can be dried and the grid mounted over an open transmission aperture in the holder. The beam path must not be blocked by a bulk substrate.

Dilution and a thin, clean support reduce overlap, multiple scattering and background. Remove excess soluble residue where compatible with the particle surface chemistry, and ensure the support and mounting provide adequate electrical conduction. The desired object is an isolated, vacuum-compatible particle layer, rather than a thick dried droplet or an opaque slab.