You may do one or more of the following (or propose your own alternatives):
This (Frank-Hertz Experiment) is straighforward, can be done using a variety of different gases, and - as an obvious extension - one can study luminescent properties. Moreover, there are many useful articles available in The American Journal of Physics. You may also wish to explore phenomena observable in a Crookes tube [Ref: pages 109-114 of Understanding the Properties of Matter, by Michael de Podesta, noting the Errata on page 112.]
Here you have the opportunity to explore dispersion (in a number of ways, in a number of media). Some demonstrations of dispersion are straightforward, others require significant work.
The all-optical measurement techniques involved here are incredibly precise. Still, at this level, the difficulties involved are quite notable.
Again, several approaches are available to you.
Well, that's not very particle-like -- is it? Be sure you come away with a clear understanding of crystal planes and Miller Indices.