In a CdSe wurtzite crystal face exposes both cations and anions. All through literature we find that, its mentioned phosphonic acids (e.g. Octadecylphosphonic acid) binds to the nonpolar face, promoting growth along polar (which exposes only Se atoms) and ( which exposes only Cd atoms) faces resulting in the formation of rods, tetrapods etc. Why don't they bind to Cd atom face eg which being polar should be more attractive for negatively charged anion phophonate? Also whats up with the , & faces?