An investigation of two-dimensional arrays of thiolized Pd nanocrystals

Two-dimensional arrays of Pd nanocrystals of varying diameters (1.8-6.0 nm) have been obtained after thiolization with alkane thiols of different chai n lengths (C-4-C-16) The stability and structure of these arrays have been explained in terms of the ratio of the particle diameter (d) and the alkane chain length (l). The experimental d-l phase diagram finds support from mo del calculations, which treat the thiolized nanocrystals as soft spheres. G enerally, a till value between 1.5 and 3.8 gives crystalline arrays extende d over several microns. For d/l values smaller than 1.5 and greater than 4. 0, the nanocrystal arrays are disordered or form low-order structures.