Please let us know what a "size of a particle" could be.
Radiocrystallographists use the width of X diffraction rays to evaluate the size of the diffracting crystallites. So clays give broad diffration peaks on a Debye-Scherrer diffractograms, though silts give fine peaks. I could confuse in justice an international crook by such facts. To give precise spots or peaks, the Bragg law demands large crystallites, and monochromatic waves, so with long and broad spindle of each incident quanton, photon or neutron or electron.
For instance, we obtained broad spots by diffracting electrons on a carbide inclusion in a Laue diffractogram, in a Siemens electronic microscope. The monochromaticicty of the electrons was not so perfect, and maybe the carbide inclusion was not a so perfect crystal.
When you write or say "size of a particle", you surrepticiously mean that it is or can be a corpuscle. But where are the experiments that could support such a postulate ?
A little more has to be known : the broglian period, frequency and when moving the broglian wavelength, suffice when an electron interferes with itself - in an Aharanov-Bohm experiment, for instance.
But when an electron interferes whith electromagnetic fields, a photon for instance in a Compton diffusion, then the intervening period is the Dirac-Schrödinger, \frac{h}{2mc^2}, half of the broglian one. So is the wavelength, too.
