Which technique can be used to clarify whether the individual metals are homogenously mixed or are arranged in the bimetallic or trimetallic nanoparticle array?
You an perform XPS on your sample to know what type of bonding your elements are linked to. By that, you will know if the metals are mixed (according to their binding energy) or if they have formed any other phase (or bonds, according to their chemical states) inside your sample.