Have any Quantum experiments been carried out concerning "Particle Shadows"?

A shadow is the absence of light. Light is a spectrum of which visible light occupies but a tiny sliver. Objects can cast shadows in any part of the the spectrum. Conversely, all objects are transparent to some parts of the spectrum. A particle casts a shadow if it absorbs or reflects a photon. Whether a particle absorbs or reflects a photon depends on the size of the illuminated particle, its composition -- which dictates its energy band characteristics -- and the wavelength of the impinging light. To see a shadow, you must also be able to detect the light with sufficient accuracy to also detect the absence of light in that particular place. X-ray crystallography is an example of a technique for determining the atomic structure of a material by looking at the shadows and reflections cast by x-rays passing through a material. I'm not aware of a specific experiment to do what you're asking, but your experiment doesn't make a lot of sense to me. Given the size of an atomic-scale particle (note, I don't say quantum particle because all particles are quantum -- indeed, everything is quantum), the wavelength of light needed to image it is so small that it would greatly perturb the object under observation. So whether or not you saw a shadow would be highly dependent on the apparatus and I doubt you would be able to get the accuracy you desired. Anyway, it's unclear to me just what point you're trying to make or what you're trying to prove?

Due to the effects of diffraction, I don't think there would be any well defined shadows on the atomic level (mind you I am no expert).